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Background: Mask leak and airway obstruction are common with mask ventilation in newborn infants, leading to suboptimal ventilation. We aimed to perform a pilot study measuring respiratory mechanics during one-person and two-person mask ventilation in preterm infants at birth., Methods: Infants less than 30 weeks' gestation were eligible for the study. In the two-person method, one person holds the mask in place and the other provides positive pressure ventilation compared with the standard one-person mask hold. A respiratory function monitor was used in line with a T-piece resuscitator to measure mask leak and airway obstruction. Deferred consent was obtained., Results: Twenty-five infants were recruited. The mean (SD) birth weight was 920.4 g (188.3), and mean (SD) gestational age was 27.3 weeks (3.0). Percentage mask leak was higher in the one-person mask method (26.4±18.5) compared with the two-person mask method (17.6±9.3) (p = 0.018). The mean (SD) expired tidal volume (V Te , mL) in breaths with leak was 3.9 (1.57) in the one-person method compared with 3.05 (1.0) the two-person method (p=0.31). A significantly lower mean (SD) end-tidal carbon dioxide (EtCO 2, mm Hg) was measured at 25.3 (9.9) in breaths with mask leak, compared with 30.8 (12.1) in breaths without leak. The breaths with airway obstruction had lower mean EtCO 2 (25.9 vs 30.8, p=0.003) and lower mean V Te (1.71 vs 6.95, p<0.001)., Conclusion: Mask leak and airway obstruction are common in resuscitation of preterm infants at birth. The use of the two-person mask technique is effective and it could be a useful option if mask ventilation with the one-person method is not effective., Trial Registration Number: ACTRN12614000245695., Competing Interests: Competing interests: None., (© Author(s) (or their employer(s)) 2023. Re-use permitted under CC BY-NC. No commercial re-use. See rights and permissions. Published by BMJ.)

Emergency research studies are high-stakes studies that are usually performed on the sickest patients, where many patients or guardians have no opportunity to provide full informed consent prior to participation. Many emergency studies self-select healthier patients who can be informed ahead of time about the study process. Unfortunately, results from such participants may not be informative for the future care of sicker patients. This inevitably creates waste and perpetuates uninformed care and continued harm to future patients. The waiver or deferred consent process is an alternative model that may be used to enroll sick patients who are unable to give prospective consent to participate in a study. However, this process generates vastly different stakeholder views which have the potential to create irreversible impediments to research and knowledge. In studies involving newborn infants, consent must be sought from a parent or guardian, and this adds another layer of complexity to already fraught situations if the infant is very sick. In this manuscript, we discuss reasons why consent waiver or deferred consent processes are vital for some types of neonatal research, especially those occurring at and around the time of birth. We provide a framework for conducting neonatal emergency research under consent waiver that will ensure the patient's best interests without compromising ethical, beneficial, and informative knowledge acquisition to improve the future care of sick newborn infants., (© 2023 S. Karger AG, Basel.)

Introduction: In neonatal resuscitation, T-piece resuscitator (TPR) are used widely, but the evidence is limited for their use in infants born at term gestation. The aim of this study was to compare the delivered positive end expiratory pressure (PEEP) and respiratory system resistance ( R rs) using TPR and self-inflating bag (SIB) in a cadaveric piglet model., Methods: Cadaveric newborn piglets were tracheotomised, intubated (cuffed tube) and leak tested. Static lung compliance was measured. Positive pressure ventilation was applied by TPR and SIB in a randomized sequence with varying, inflations per minute (40, 60 and 80 min) and peak inspiratory pressures (18 and 30 cmH 2 O). PEEP was constant at 5 cmH 2 O. The lungs were washed with saline and static lung compliance was re-measured; ventilation sequences were repeated. Lung inflation data for the respiratory mechanics were measured using a respiratory function monitor and digitally recorded for both pre and post-lung wash inflation sequences. A paired sample t -test was used to compare the mean and standard deviation., Results: The mean difference in PEEP (TPR vs. SIB) was statistically significant at higher inflation rates of 60 and 80 bpm. At normal lung compliance, mean difference was 1.231 ( p  = 0.000) and 2.099 ( p  = 0.000) with PIP of 18 and 30 cmH 2 O respectively. Significantly higher R rs were observed when using a TPR with higher inflation rates of 60 and 80 bpm at varying lung compliance., Conclusion: TPR is associated with significantly higher PEEP in a compliant lung model, which is probably related to the resistance of the TPR circuit. The effect of inadvertent PEEP on lung mechanics and hemodynamics need to be examined in humans. Further studies are needed to assess devices used to provide PEEP (TPR, SIB with PEEP valve, Anaesthetic bag with flow valve) during resuscitation of the newborn., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (© 2022 Shah, Tracy, Hinder and Badawi.)

This review addresses regional oxygenation and perfusion changes for preterm infants and changes with body position, with or without head rotation. Future directions for improving neurodevelopmental and clinical outcomes are suggested. The MEDLINE, Embase and Scopus databases were searched up to July 2021. Fifteen out of 470 studies met the inclusion criteria. All were prospective, observational studies with a moderate risk of bias. Significant variation was found for the baseline characteristics of the cohort, postnatal ages, and respiratory support status at the time of monitoring. When placed in a non-supine position, preterm infants showed a transient reduction in cardiac output and stroke volume without changes to heart rate or blood pressure. No studies reported on long-term neurodevelopmental outcomes. Overall, side lying or prone position does not appear to adversely affect regional, and specifically cerebral, oxygenation or cerebral perfusion. The effect of head rotation on regional oxygenation and perfusion remains unclear., (Copyright © 2021 Elsevier Ltd. All rights reserved.)

A firm concept of time is essential for establishing causality in a clinical setting. Review of critical incidents and generation of study hypotheses require a robust understanding of the sequence of events but conducting such work can be problematic when timestamps are recorded by independent and unsynchronized clocks. Most clinical models implicitly assume that timestamps have been measured accurately and precisely, but this custom will need to be re-evaluated if our algorithms and models are to make meaningful use of higher frequency physiological data sources. In this narrative review we explore factors that can result in timestamps being erroneously recorded in a clinical setting, with particular focus on systems that may be present in a critical care unit. We discuss how clocks, medical devices, data storage systems, algorithmic effects, human factors, and other external systems may affect the accuracy and precision of recorded timestamps. The concept of temporal uncertainty is introduced, and a holistic approach to timing accuracy, precision, and uncertainty is proposed. This quantitative approach to modeling temporal uncertainty provides a basis to achieve enhanced model generalizability and improved analytical outcomes., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest. The reviewer BRC declared a shared affiliation with the author PL to the handling editor at the time of review., (Copyright © 2022 Goodwin, Eytan, Dixon, Goodfellow, Doherty, Greer, McEwan, Tracy, Laussen, Assadi and Mazwi.)

Contemporary packed red blood cell transfusion practices in anaemic preterm infants are primarily based on measurement of hemoglobin or haematocrit. In neonatal intensive care units, most preterm infants receive at least 1 packed red cell transfusion as standard treatment for anaemia of prematurity. Clinicians are faced with a common question "at what threshold should anaemic preterm infants receive packed red blood cell transfusion?". While evidence from interventional trials offers a range of haemoglobin levels to clinicians on thresholds to initiate red cell transfusion, it does not offer identification of exact haemoglobin level at which regional oxygenation and perfusion gets compromised. Assessment of regional oxygenation using near infrared spectroscopy and perfusion using ultrasound could offer a personalized transfusion medicine approach to optimize transfusion practices. We conducted a systematic review of the literature to identify the role of both regional oxygenation and/or ultrasound-based perfusion monitoring as a potential trigger to initiate packed red blood cell transfusion in anaemic preterm infants. MEDLINE, Embase, Maternity and Infant Care database were searched up to March 2021. Publications identified were screened and relevant data was extracted. Changes to regional oxygenation and/or perfusion monitoring before and after packed red blood cell transfusion were the primary outcomes. 44 out of 755 studies met the inclusion criteria and were included in the final analysis. Most were prospective, observational studies in stable preterm infants. Overall, studies reported an improvement in regional oxygenation and/or ultrasound-based perfusion after packed red blood cell transfusion. These changes were more consistently observed when hemoglobin <9.6g/dL or hematocrit was <0.30. Significant variation was found for patient characteristics, postnatal age at the time of monitoring, criteria for diagnosis of anaemia, and period of monitoring as well as regional oxygenation monitoring methodology. Regional oxygenation and/or perfusion monitoring can identify at-risk anaemic preterm infants and are promising tools to individualize packed red blood cell transfusion practices. However, there is lack of evidence for incorporating this monitoring, in their present form, into standard clinical practice. Additionally, consistency in reporting of study methodology should be improved., (Copyright © 2021. Published by Elsevier Inc.)

Background: The administration of live microbiota (probiotic) via enteral route to preterm infants facilitates intestinal colonization with beneficial bacteria, resulting in competitive inhibition of the growth of pathogenic bacteria preventing gut microbiome dysbiosis. This dysbiosis is linked to the pathogenesis of necrotizing enterocolitis (NEC), an acquired multi-factorial intestinal disease characterized by microbial invasion of the gut mucosa, particularly affecting preterm infants. Probiotic prophylaxis reduces NEC; however, variations in strain-specific probiotic effects, differences in administration protocols, and synergistic interactions with the use of combination strains have all led to challenges in selecting the optimal probiotic for clinical use. Aim: To compare any differences in NEC rates, feeding outcomes, co-morbidities in preterm infants receiving single or two-strain probiotics over a 4-year period. The two-strain probiotic prophylaxis was sequentially switched over after 2 years to the single strain probiotic within this 4-year study period, in similar cohort of preterm infants. Methods: During two consecutive equal 2-year epochs, preterm infants (<32 weeks and or with birth weight <1,500 g) receiving two-strain ( Lactobacillus acidophilus and Bifidobacterium bifidum ) and single strain (Bifidobacterium breve M-16 V,) probiotic prophylaxis for prevention of NEC were included in this retrospective, observational study. The primary outcome included rates of NEC; secondary outcomes included prematurity related co-morbidities and feeding outcomes. Time to reach full enteral feeds was identified as the first day of introducing milk feeds at 150 ml/kg/day. Results: There were 180 preterm infants in the two-strain, 196 in the single strain group from the two equal consecutive 2-year epochs. There were no differences in the NEC rates, feeding outcomes, all-cause morbidities except for differences in rates of retinopathy of prematurity. Conclusion: In our intensive-care setting, clinical outcomes of single vs. two-strain probiotic prophylaxis for prevention of NEC were similar. Although our study demonstrates single strain probiotic may be equally effective than two-strain in the prevention of NEC, small sample size and low baseline incidence of NEC in our unit were not sufficiently powered to compare single vs. two-strain probiotic prophylaxis in preventing NEC. Further clustered randomized controlled trials are required to study the effects of single vs. multi-strain probiotic products for NEC prevention in preterm infants., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2021 Priyadarshi, Lowe, Saddi, Trivedi, Luig and Tracy.)

Objectives: To evaluate cerebral tissue oxygenation (cTOI) and cerebral perfusion in preterm infants in supine vs prone positions., Study Design: Sixty preterm infants, born before 32 weeks of gestation, were enrolled; 30 had bronchopulmonary dysplasia (BPD, defined as the need for respiratory support and/or supplemental oxygen at 36 weeks of postmenstrual age). Cerebral perfusion, cTOI, and polysomnography were measured in both the supine and prone position with the initial position being randomized. Infants with a major intraventricular hemorrhage or major congenital abnormality were excluded., Results: Cerebral perfusion was unaffected by position or BPD status. In the BPD group, the mean cTOI was higher in the prone position compared with the supine position by a difference of 3.27% (P = .03; 95% CI 6.28-0.25) with no difference seen in the no-BPD group. For the BPD group, the burden of cerebral hypoxemia (cumulative time spent with cTOI <55%) was significantly lower in the prone position (23%) compared with the supine position (29%) (P < .001). In those without BPD, position had no effect on cTOI., Conclusions: In preterm infants with BPD, the prone position improved cerebral oxygenation and reduced cerebral hypoxemia. These findings may have implications for positioning practices. Further research will establish the impact of position on short- and long-term developmental outcomes., (Copyright © 2021 Elsevier Inc. All rights reserved.)

Background: Resuscitation of infants using T-piece resuscitators (TPR) allow positive pressure ventilation with positive end-expiratory pressure (PEEP). The adjustable PEEP valve adds resistance to expiration and could contribute to inadvertent PEEP. The study indirectly investigated risk of inadvertent peep by determining expiratory time constants. The aim was to measure system expiratory time constants for a TPR device in a passive mechanical model with infant lung properties. Methods: We used adiabatic bottles to generate four levels of compliance (0.5-3.4 mL/cm H 2 O). Expiratory time constants were recorded for combinations of fresh gas flow (8, 10, 15 L/min), PEEP (5, 8, 10 cm H 2 O), airway resistance (50, 200 cm H 2 O/L/sec and none), endotracheal tube (none, size 2.5, 3.0, 3.5) with a peak inflation pressure of 15 cm H 2 O above PEEP. Results: Low compliances resulted in time constants below 0.17 s contrasting to higher compliances where the expiratory time constants were 0.25-0.81 s. Time constants increased with increased resistance, lower fresh gas flows, higher set PEEP levels and with an added airway resistance or endotracheal tube. Conclusions: The risk of inadvertent PEEP increases with a shorter time for expiration in combination with a higher compliance or resistance. The TPR resistance can be reduced by increasing the fresh gas flow or reducing PEEP. The expiratory time constants indicate that this may be clinically important. The risk of inadvertent PEEP would be highest in intubated term infants with highly compliant lungs. These results are useful for interpreting clinical events and recordings., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2021 Drevhammar, Falk, Donaldsson, Tracy and Hinder.)

Objectives: We compared intrapartum interventions and outcomes for mothers, neonates and children up to 16 years, for induction of labour (IOL) versus spontaneous labour onset in uncomplicated term pregnancies with live births., Design: We used population linked data from New South Wales, Australia (2001-2016) for healthy women giving birth at 37+0 to 41+6 weeks. Descriptive statistics and logistic regression were performed for intrapartum interventions, postnatal maternal and neonatal outcomes, and long-term child outcomes adjusted for maternal age, country of birth, socioeconomic status, parity and gestational age., Results: Of 474 652 included births, 69 397 (15%) had an IOL for non-medical reasons. Primiparous women with IOL versus spontaneous onset differed significantly for: spontaneous vaginal birth (42.7% vs 62.3%), instrumental birth (28.0% vs 23.9%%), intrapartum caesarean section (29.3% vs 13.8%), epidural (71.0% vs 41.3%), episiotomy (41.2% vs 30.5%) and postpartum haemorrhage (2.4% vs 1.5%). There was a similar trend in outcomes for multiparous women, except for caesarean section which was lower (5.3% vs 6.2%). For both groups, third and fourth degree perineal tears were lower overall in the IOL group: primiparous women (4.2% vs 4.9%), multiparous women (0.7% vs 1.2%), though overall vaginal repair was higher (89.3% vs 84.3%). Following induction, incidences of neonatal birth trauma, resuscitation and respiratory disorders were higher, as were admissions to hospital for infections (ear, nose, throat, respiratory and sepsis) up to 16 years. There was no difference in hospitalisation for asthma or eczema, or for neonatal death (0.06% vs 0.08%), or in total deaths up to 16 years., Conclusion: IOL for non-medical reasons was associated with higher birth interventions, particularly in primiparous women, and more adverse maternal, neonatal and child outcomes for most variables assessed. The size of effect varied by parity and gestational age, making these important considerations when informing women about the risks and benefits of IOL., Competing Interests: Competing interests: None declared., (© Author(s) (or their employer(s)) 2021. Re-use permitted under CC BY-NC. No commercial re-use. See rights and permissions. Published by BMJ.)

Infant resuscitation devices used at birth must be capable of delivering adequate and consistent ventilation in a controlled and predictable manner to a wide patient weight range, and combinations of transitional lung states. Manual inflation resuscitation devices delivering positive pressure lung inflation at birth can be classified broadly into two types: 1) flow generating, ie silicone self-inflating bags (SIB) also known as bag valve mask (BVM) and 2) flow dependent, ie anaesthetic flow inflating bag (FIB) and t-piece resuscitator (TPR) systems (eg: Neopuff, GE Panda and Draeger Resuscitaires). Globalization, lower production costs, and an expanding market need for devices, has led to a proliferation of brands (both reusable and single use) within a class type. T-piece resuscitators have become the dominant device particularly in high income countries. There remains a paucity of information on the performance characteristics of these devices and their ability to provide the required respiratory parameters for effective and safe ventilation across the full-expected weight range and lung states to which they will be applied. This review aims to inform current clinical practise on the biomechanical efficiency, reliability and efficacy of the most common devices used to apply PPV to newborns and infants ≤10 kgs., (Copyright © 2021 Elsevier Ltd. All rights reserved.)

Background: T-piece resuscitators (TPRs) are used for primary newborn resuscitation in birthing and emergency rooms worldwide. A recent study has shown spikes in peak inflation pressure (PIP) over set values with two brands of TPRs inbuilt into infant warmer/resuscitation platforms. We aimed to compare delivered ventilation between two TPR drivers with inflation pressure spikes to a standard handheld TPR in a low test lung compliance (Crs), leak-free bench test model., Methods: A single operator provided positive pressure ventilation to a low compliance test lung model (Crs 0.2-1 mL/cmH 2 O) at set PIP of 15, 25, 35 and 40 cmH 2 O. Two TPR devices with known spikes (Draeger Resuscitaire, GE Panda) were compared with handheld Neopuff (NP). Recommended settings for positive end-expiratory pressure (5 cmH 2 O), inflation rate of 60/min and gas flow rate 10 L/min were used., Results: 2293 inflations were analysed. Draeger and GE TPR drivers delivered higher mean PIP (Panda 18.9-49.5 cmH2O; Draeger 21.2-49.2 cmH2O and NP 14.8-39.9 cmH2O) compared with set PIP and tidal volumes (TVs) compared with the NP (Panda 2.9-7.8 mL; Draeger 3.8-8.1 mL; compared with NP 2.2-6.0 mL), outside the prespecified acceptable range (±10% of set PIP and ±10% TV compared with NP)., Conclusion: The observed spike in PIP over set values with Draeger and GE Panda systems resulted in significantly higher delivered volumes compared with the NP with identical settings. Manufacturers need to address these differences. The effect on patient outcomes is unknown., Competing Interests: Competing interests: None declared., (© Author(s) (or their employer(s)) 2021. No commercial re-use. See rights and permissions. Published by BMJ.)

Objective: to analyse women's experiences of early labour care in caseload midwifery in Australia., Design: this study sits within a multi-site randomised controlled trial of caseload midwifery versus standard care. Participant surveys were conducted at 6-weeks and 6-months after birth. Free-text responses about experiences of care were subject to critical thematic analysis in NVivo 11 software., Setting: two urban Australian hospitals in different states., Participants: women 18 years and over, with a singleton pregnancy, less than 24 weeks' pregnant, not planning a caesarean section or already booked with a care provider; were eligible to participate in the trial., Interventions: participants were randomised to caseload midwifery or standard care for antenatal, labour and birth and postpartum care., Measurements and Findings: The 6-week survey response rate was 58% (n = 1,019). The survey included five open questions about women's experiences of pregnancy, labour and birth, and postnatal care. Nine-hundred and one respondents (88%) provided free text comments which were coded to generate 10 categories. The category of early labour contained data from 84 individual participants (caseload care n = 44; standard care n = 40). Descriptive themes were: (1) needing permission; (2) doing the 'wrong' thing; and (3) being dismissed. Analytic themes were: (1) Seeking: women wanting to be "close to those who know what's going on"; and (2) Shielding: midwives defending resources and normal birth., Key Conclusions: Regardless of model of care, early labour care was primarily described in negative terms. This could be attributed to reporting bias, because women who were neutral about early labour care may not comment. Nevertheless, the findings demonstrate a gap in knowledge about early labour care in caseload midwifery models., Implications for Practice: Maternity services that offer caseload midwifery are ideally placed to evaluate how early labour home visiting impacts women's experiences of early labour., Competing Interests: Declaration of Competing Interest None declared, (Copyright © 2020 Elsevier Ltd. All rights reserved.)

Background: Very low birthweight or preterm infants are at increased risk of adverse outcomes including sepsis, necrotising enterocolitis, and death. We assessed whether supplementing the enteral diet of very low-birthweight infants with lactoferrin, an antimicrobial protein, reduces all-cause mortality or major morbidity., Methods: We did a multicentre, double-blind, pragmatic, randomised superiority trial in 14 Australian and two New Zealand neonatal intensive care units. Infants born weighing less than 1500 g and aged less than 8 days, were eligible and randomly assigned (1:1) using minimising web-based randomisation to receive once daily 200 mg/kg pasteurised bovine lactoferrin supplements or no lactoferrin supplement added to breast or formula milk until 34 weeks' post-menstrual age (or for 2 weeks, if longer), or until discharge from the study hospital if that occurred first. Designated nurses preparing the daily feeds were not masked to group assignment, but other nurses, doctors, parents, caregivers, and investigators were unaware. The primary outcome was survival to hospital discharge or major morbidity (defined as brain injury, necrotising enterocolitis, late-onset sepsis at 36 weeks' post-menstrual age, or retinopathy treated before discharge) assessed in the intention-to-treat population. Safety analyses were by treatment received. We also did a prespecified, PRISMA-compliant meta-analysis, which included this study and other relevant randomised controlled trials, to estimate more precisely the effects of lactoferrin supplementation on late-onset sepsis, necrotising enterocolitis, and survival. This trial is registered with the Australian and New Zealand Clinical Trials Registry, ACTRN12611000247976., Findings: Between June 27, 2014, and Sept 1, 2017, we recruited 1542 infants; 771 were assigned to the intervention group and 771 to the control group. One infant who had consent withdrawn before beginning lactoferrin treatment was excluded from analysis. In-hospital death or major morbidity occurred in 162 (21%) of 770 infants in the intervention group and in 170 (22%) of 771 infants in the control group (relative risk [RR] 0·95, 95% CI 0·79-1·14; p=0·60). Three suspected unexpected serious adverse reactions occurred; two in the lactoferrin group, namely unexplained late jaundice and inspissated milk syndrome, but were not attributed to the intervention and one in the control group had fatal inspissated milk syndrome. Our meta-analysis identified 13 trials completed before Feb 18, 2020, including this Article, in 5609 preterm infants. Lactoferrin supplements significantly reduced late-onset sepsis (RR 0·79, 95% CI 0·71-0·88; p<0·0001; I 2 =58%), but not necrotising enterocolitis or all-cause mortality., Interpretation: Lactoferrin supplementation did not improve death or major morbidity in this trial, but might reduce late-onset sepsis, as found in our meta-analysis of over 5000 infants. Future collaborative studies should use products with demonstrated biological activity, be large enough to detect moderate and clinically important effects reliably, and assess greater doses of lactoferrin in infants at increased risk, such as those not exclusively receiving breastmilk or infants of extremely low birthweight., Funding: Australian National Health and Medical Research Council., (Copyright © 2020 Elsevier Ltd. All rights reserved.)

Background: The measurement and interpretation of patient experience is a distinct dimension of health care quality. The Midwives @ New Group practice Options (M@NGO) randomized control trial of caseload midwifery compared with standard care among women regardless of risk reported both clinical and cost benefits. This study reports participants' perceptions of the quality of antenatal care within caseload midwifery, compared with standard care for women of any risk within that trial., Methods: A trial conducted at two Australian tertiary hospitals randomly assigned participants (1:1) to caseload midwifery or standard care regardless of risk. Women were sent an 89-question survey at 6 weeks postpartum that included 12 questions relating to pregnancy care. Ten survey questions (including 7-point Likert scales) were analyzed by intention to treat and illustrated by participant quotes from two free-text open-response items., Results: From the 1748 women recruited to the trial, 58% (n = 1017) completed the 6-week survey. Of those allocated to caseload midwifery, 66% (n = 573) responded, compared with 51% (n = 444) of those allocated to standard care. The survey found women allocated to caseload midwifery perceived a higher level of quality care across every antenatal measure. Notably, those women with identified risk factors reported higher levels of emotional support (aOR 2.52 [95% CI 1.87-3.39]), quality care (2.94 [2.28-3.79]), and feeling actively involved in decision-making (3.21 [2.35-4.37])., Conclusions: Results from the study show that in addition to the benefits to clinical care and cost demonstrated in the M@NGO trial, caseload midwifery outperforms standard care in perceived quality of pregnancy care regardless of risk., (© 2019 Wiley Periodicals, Inc.)

Objective: to explore whether women allocated to caseload care characterise their midwife differently to those allocated to standard care., Design: multi-site unblinded, randomised, controlled, parallel-group trial., Setting: the study was conducted in two metropolitan teaching hospitals across two Australian cities., Population: women of all obstetric risk were eligible to participate. Inclusion criteria were: 18 years or older, less than 24 week's gestation with a singleton pregnancy. Women already booked with a care provider or planning to have an elective caesarean section were excluded., Interventions: participants were randomised to caseload midwifery or standard care. The caseload model provided antenatal, intrapartum and postnatal care from a primary midwife or 'back-up' midwife; as well as consultation with obstetric or medical physicians as indicated by national guidelines. The standard model included care from a general practitioner and/or midwives and obstetric doctors., Measurements and Findings: participants' responses to open-ended questions were collected through a 6-week postnatal survey and analysed thematically. A total of 1748 women were randomised between December 2008 - May 2011; 871 to caseload midwifery and 877 to standard care. The response rate to the 6-week survey including free text items was 52% (n=901). Respondents from both groups characterised midwives as Informative, Competent and Kind. Participants in the caseload group perceived midwives with additional qualities conceptualised as Empowering and 'Endorphic'. These concepts highlight some of the active ingredients that moderated or mediated the effects of the midwifery care within the M@NGO trial., Key Conclusion: caseload midwifery attracts, motivates and enables midwives to go Above and Beyond such that women feel empowered, nurtured and safe during pregnancy, labour and birth., Implications for Practice: the concept of an Endorphic midwife makes a useful contribution to midwifery theory as it enhances our understanding of how the complex intervention of caseload midwifery influences normal birth rates and experiences. Defining personal midwife attributes which are important for caseload models has potential implications for graduate attributes in degree programs leading to registration as a midwife and selection criteria for caseload midwife positions., (Copyright © 2017 Elsevier Ltd. All rights reserved.)

Background: the viability of freestanding midwifery units in Australia is restricted, due to concerns over their safety, particularly for women and babies who, require transfer., Aim: to compare the maternal and neonatal birth outcomes of women who planned, to give birth at freestanding midwifery units and subsequently, transferred to a tertiary maternity unit to the maternal and neonatal, outcomes of a low-risk cohort of women who planned to give birth in, tertiary maternity unit., Methods: a descriptive study compared two groups of women with low-risk singleton, pregnancies who were less than 28 weeks pregnant at booking: women who, planned to give birth at a freestanding midwifery unit (n=494) who, transferred to a tertiary maternity unit during the antenatal, intrapartum or postnatal periods (n=260) and women who planned to give, birth at a tertiary maternity unit (n=3157). Primary outcomes were mode, of birth, Apgar score of less than 7 at 5minutes and admission to, special care nursery or neonatal intensive care., Key Findings: the proportion of women who experienced a caesarean section was lower, among the freestanding midwifery unit women who transferred during the, intrapartum/postnatal period compared to women in the tertiary maternity, unit group (16.1% versus 24.8% respectively). Other outcomes were, comparable between the cohorts. Rates of primary outcomes in relation to, stage of transfer varied when stratified by parity., Discussion: these descriptive results support the provision of care in freestanding, midwifery units as an alternative to tertiary maternity units for women, with low risk pregnancies at the time of booking. A larger study, powered, to determine statistical significance of any differences in outcomes, is, required., (Copyright © 2017 Elsevier Ltd. All rights reserved.)

Objectives: to examine the transfers from primary maternity units to a tertiary hospital in New Zealand by describing the frequency, timing, reasons and outcomes of those who had antenatal or pre-admission birthplace plan changes, and transfers in labour or postnatally., Design: mixed methods prospective (concurrent) cohort study, which analysed transfer and clinical outcome data (407 primary unit cohort, 285 tertiary hospital cohort), and data from the six week postpartum survey (571 respondents)., Participants and Setting: well, pregnant women booked to give birth in a tertiary maternity hospital or primary maternity unit in one region in New Zealand (2010-2012). All women received midwifery continuity of care, regardless of their intended or actual birthplace., Results: fewer than half of the women who planned a primary unit birth gave birth there (191 or 46.9%). A change of plan may have been made either antenatally or before admission in labour; and transfers were made after admission to the primary unit in labour or during the postnatal stay (about 48 hours). Of the 117 (28.5%) planning a primary unit birth who changed their planned birthplace type antenatally 73 (62.4%) were due to a clinical indication. Earthquakes accounted for 28.1% of birthplace change (during the research period major earthquakes occurred in the study region). Most (73.8%) labour changes occurred before admission in labour to the primary unit. For the 76 women who changed plan at this stage the most common reasons to do so were a rapid labour (25.0%) or prolonged rupture of membranes (23.7%). Transfers in labour from primary unit to tertiary hospital occurred for 27 women (12.6%) of whom 26 (96.3%) were having their first baby. "Slow progress" of labour accounted for 21 (77.8%) of these and 17 (62.9%) were classified as 'non-emergency'. The average transfer time for 'emergency' transfers was 58 minutes. The average time for all labour transfers from specialist consultation to birth was 4.5 hours. Nine postnatal transfers (maternal or neonatal) from a primary unit occurred (4.7%), making a total post-admission transfer rate of 17.3% for the primary unit cohort., Key Conclusions: birthplace changes were not uncommon, with many women changing their birthplace plan antenatally or prior to admission in labour and some transferring between facilities during or soon after birth. Most changes were due to the development of complications or 'risk factors'. Most transfers were not urgent and took approximately one hour from the decision to arrival at the tertiary hospital. Despite the transfers the neonatal clinical outcomes were comparable between both primary and tertiary cohorts, and there was higher maternal morbidity in the tertiary cohort., Implications for Practice: although the study size is relatively small, its comprehensive documentation of transfers has the potential to inform future research and the birthplace decision-making of childbearing women and midwives., (Copyright © 2015 The Authors. Published by Elsevier Ltd.. All rights reserved.)

Aim: To determine changes in respiratory mechanics when chest compressions are added to mask ventilation, as recommended by the International Liaison Committee on Resuscitation (ILCOR) guidelines for newborn infants., Methods: Using a Laerdal Advanced Life Support leak-free baby manikin and a 240-mL self-inflating bag, 58 neonatal staff members were randomly paired to provide mask ventilation, followed by mask ventilation with chest compressions with a 1:3 ratio, for two minutes each. A Florian respiratory function monitor was used to measure respiratory mechanics, including mask leak., Results: The addition of chest compressions to mask ventilation led to a significant reduction in inflation rate, from 63.9 to 32.9 breaths per minute (p < 0.0001), mean airway pressure reduced from 7.6 to 4.9 cm H2 O (p < 0.001), minute ventilation reduced from 770 to 451 mL/kg/min (p < 0.0001), and there was a significant increase in paired mask leak of 6.8% (p < 0.0001)., Conclusion: Adding chest compressions to mask ventilation, in accordance with the ILCOR guidelines, in a manikin model is associated with a significant reduction in delivered ventilation and increase in mask leak. If similar findings occur in human infants needing an escalation in resuscitation, there is a potential risk of either delay in recovery or inadequate response to resuscitation., (©2014 Foundation Acta Paediatrica. Published by John Wiley & Sons Ltd.)

Objective: this paper describes the pilot study that was undertaken to test the feasibility of the recruitment plan designed to recruit women who booked to give birth in two freestanding midwifery units in NSW, Australia. The pilot preceded the full prospective cohort study, Evaluating Midwifery Units (EMU), which aimed to examine the antenatal, birth and postnatal outcomes of women planning to give birth in freestanding midwifery units compared to those booked to give birth in tertiary level maternity units in Australia and New Zealand., Design: a prospective cohort study with two mutually-exclusive cohorts., Setting: two freestanding midwifery units in NSW and their corresponding tertiary referral hospitals., Participants: a total of 146 women with few identified risk factors recruited between 13 September 2009 and 31 March 2010 whose planned place of birth was either a freestanding midwifery unit or tertiary maternity unit., Measurements and Findings: the pilot study identified the feasibility of relying on the booking midwife to recruit eligible women from several antenatal booking clinics to the study. Low rates of eligible women were invited resulting in a lower than expected consent rate. In addition, although mostly only low-risk women were invited to participate, some women requiring medical consultation at the time of booking were inadvertently recruited into the study. The results of this pilot study led us to revise the study protocol to find ways of including the outcomes of all women without identified risk factors who booked at either the freestanding midwifery units or the tertiary referral hospital in that area. This paper describes the revisions that were made to the study plan., Key Conclusions: five lessons were learned from the pilot study. We found that recruitment protocols employed for the cohort study were too complicated and required simplification to maximise the potential of the study. The study protocol needed to be changed for the main study to ensure a larger sample size and to ensure the risk profile of each cohort was as similar as possible. Sources of data needed to be expanded to produce a complete data set., Implications for Practice: pilot studies are extremely useful tools in testing methods to inform research protocols. We found that the first months spent undertaking a pilot study ensured a stronger design with the potential to show more meaningful results., (Crown Copyright © 2012. Published by Elsevier Ltd. All rights reserved.)

Background: the option of giving birth in water is available to most women in birth centres in Australia but there continues to be resistance in mainstream delivery wards due to safety concerns. Women in birth centres are more likely to give birth in upright positions and be attended by experienced midwives and obstetricians who are comfortable facilitating normal birth. The aim of this study was to determine rates of perineal trauma, postpartum haemorrhage and five-minute Apgar scores amongst low risk women in a birth centre who gave birth in water compared to six birth positions on land., Methods: this was a descriptive cross sectional study of births occurring in a large alongside Sydney birth centre from January 1996 to April 2008. Handwritten records were kept by midwives on each birth in the birth centre over twelve and a half years (n=6,144). Descriptive statistics and logistic regression were applied controlling for risk factors for perineal trauma, postpartum haemorrhage and the five-minute Apgar score., Findings: waterbirth (13%) and six main birth positions on land were identified: kneeling/all fours (48%), semi-recumbent (12%), lateral (5%), standing (8%), birth stool (10%) and squatting (3%). Compared to waterbirth, birth on a birth stool led to a higher rate of major perineal trauma (second, third, fourth degree tear and episiotomy) (OR 1.40 [1.12-1.75]) and postpartum haemorrhage (OR 2.04 [1.44-2.90]). Compared to waterbirth, babies born in a semi-recumbent position had a significantly greater incidence of five-minute Apgar scores <7 (OR 4.61 [1.29-16.52])., Conclusions: waterbirth does not lead to more infants born with Apgar score <7 at 5 mins when compared to other birth positions. Waterbirth provides advantages over the birth stool for maternal outcomes of major perineal trauma and postpartum haemorrhage., (Copyright © 2012 Elsevier Ltd. All rights reserved.)

This study investigated whether arterial blood pressure waveform analysis could be useful for estimating left ventricular outflow (LVO) and total peripheral resistance (TPR) in preterm infants. A cohort of 27 infants were studied, with 89 measurements of left ventricular outflow (LVO) using Doppler echocardiography and arterial pressure using catheters, performed in 0, 12, 24 and 36 hours after birth. TPR was computed as mean arterial pressure divided by LVO. The diastolic decay rate (1/τ) was obtained via fitting an exponential function to the last one third of each arterial pulse, with the mean rate computed from 50 pulses selected from each infant. This decay rate was considered to be inversely related to TPR while positively related to LVO. The results of regression analysis have confirmed that the diastolic decay rate had significant positive and negative relationships with LVO and TPR respectively(r = 0.383, P = 0.0002 and r = -0.379, P = 0.0002 respectively). These preliminary results demonstrated the potential utility of arterial pressure waveform analysis for estimating LVO and TPR in preterm infants, but more advanced multi-parameter models may be needed to improve accuracy of the estimation.

Near-infrared spectroscopy (NIRS) for cerebral circulation monitoring has gained popularity in the neonatal intensive care setting, with studies showing the possibility of identifying preterm infants with intraventricular hemorrhage (IVH) by transfer function analysis of arterial blood pressure (BP) and NIRS measures. In this study, we examined a number of NIRS-derived measures in a cohort of preterm infants with IVH (n = 5) and without IVH (n = 12) within 1-3 hours after birth. The IVH infants were found to have significantly higher tissue oxygenation index (TOI), lower fractional tissue oxygen extraction (FTOE) and lower coherence between arterial BP and deoxygenated hemoglobin (HHb) in the very low frequency range (VLF, 0.02-0.04 Hz). Further studies with larger sample size are warranted for a more complete understanding of the clinical utility of these NIRS measures for early identification of IVH infants.

Aim: The aim of the study is to compare mask leak and delivered ventilation during Neopuff (NP) mask ventilation in two modes: (i) with NP pressure dial hidden and resuscitator watching chest wall (CW) rise with, (ii) CW movement hidden and resuscitator watching NP pressure dial., Methods: Thirty-six participants gave mask ventilation to a modified manikin designed to measure mask leak and delivered ventilation for two minutes in each mode randomly assigned. Paired t-tests were used to analyse differences in mean values. Linear regression was used to determine the association of mask leak with delivered ventilation., Results: Of 7277 inflations analysed, 3621 were observing chest wall mode (CWM) and 3656 observing NP mode (NPM). Mask leak was similar between the groups; 31.6% for CWM and 31.5% (p = 0.56) for NPM. There were no significant differences in airways pressures and expired tidal volumes (TVe) between modes. Mask leak was strongly associated with TVe (R = -0.86 p < 0.0001) and with peak inspiratory pressure (PIP) (R = -0.51 p < 0.0001). TVe was associated with PIP (R = 0.51 p < 0.0001)., Conclusion: This study provides reassurance that NP mask leak is not greater when resuscitators watch the NP pressure dial. Mask leak is related to TVe. Mask ventilation training with manikins should include tidal volume measurements., (© 2010 The Author(s)/Journal Compilation © 2010 Foundation Acta Paediatrica.)

Lipid nanoparticles (LNPs) have proven to be highly efficient carriers of short-interfering RNAs (siRNAs) to hepatocytes in vivo; however, the precise mechanism by which this efficient delivery occurs has yet to be elucidated. We found that apolipoprotein E (apoE), which plays a major role in the clearance and hepatocellular uptake of physiological lipoproteins, also acts as an endogenous targeting ligand for ionizable LNPs (iLNPs), but not cationic LNPs (cLNPs). The role of apoE was investigated using both in vitro studies employing recombinant apoE and in vivo studies in wild-type and apoE(-/-) mice. Receptor dependence was explored in vitro and in vivo using low-density lipoprotein receptor (LDLR(-/-))-deficient mice. As an alternative to endogenous apoE-based targeting, we developed a targeting approach using an exogenous ligand containing a multivalent N-acetylgalactosamine (GalNAc)-cluster, which binds with high affinity to the asialoglycoprotein receptor (ASGPR) expressed on hepatocytes. Both apoE-based endogenous and GalNAc-based exogenous targeting appear to be highly effective strategies for the delivery of iLNPs to liver.

Background: Neonatal intensive care and special care nurseries provide a level of care that is both high in cost and low in volume. The aim of our study was to determine the rate of admission of term babies to neonatal intensive care in association with each method of giving birth among low-risk women., Methods: We examined the records of 1,001,249 women who gave birth in Australia during 1999 to 2002 using data from the National Perinatal Data Collection. Among low-risk women, we calculated the adjusted odds of admission to neonatal intensive care at term separated for each week of gestational age between 37 and 41 completed weeks. We also calculated the odds of admission to neonatal intensive care in association with cesarean section before or after the onset of labor, and vacuum or instrumental birth compared with unassisted vaginal birth at 40 weeks' gestation., Results: The overall rate of admission to neonatal intensive care of term babies was 8.9 percent for primiparas and 6.3 percent for multiparas. After a cesarean section before the onset of labor, the adjusted odds of admission among low-risk primiparas at 37 weeks' gestation were 12.08 (99% CI 8.64-16.89); at 38 weeks, 7.49 (99% CI 5.54-10.11); and at 39 weeks, 2.80 (99% CI 2.02-3.88). At 41 weeks, the adjusted odds were not significantly higher than those at 40 weeks' gestation. Among low-risk multiparas who had a cesarean section before the onset of labor, the adjusted odds of admission to neonatal intensive care at 37 weeks' gestation were 15.40 (99% CI 12.87-18.43); at 38 weeks, 12.13 (99% CI 10.37-14.19); and at 39 weeks, 5.09 (99% CI 4.31-6.00). At 41 weeks' gestation, the adjusted odds of admission were significantly lower than those at 40 weeks (AOR 0.64, 99% CI 0.47-0.88). Babies born after any operative method of birth were at increased odds of being admitted to neonatal intensive care compared with those born after unassisted vaginal birth at 40 weeks' gestation., Conclusions: The adjusted odds of admission to neonatal intensive care for babies of low-risk women were increased after birth at 37 weeks' gestation. In a climate of rising cesarean sections, this information is important to women who may be considering elective procedures.

Introduction: Despite concern over high rates of operative birth in many countries, particularly amongst low risk healthy women, the obstetric antecedents of operative birth are poorly described. We aimed to determine the association between interventions introduced during labour with interventions in the birth process amongst women of low medical risk., Methods: We undertook a population-based descriptive study of all low risk women amongst the 753,895 women who gave birth in Australia during 2000-2002. Adjusted odds ratios (AOR) were calculated using multinomial logistic regression to describe the association between mode of birth and each of four labour intervention subgroups separately for primiparous and multiparous women., Results: We observed increased rates of operative birth in association with each of the interventions offered during the labour process. For first time mothers the association was particularly strong., Conclusions: This study underlines the need for better clinical evidence of the effects of epidurals and pharmacological agents introduced in labour. At a population level it demonstrates the magnitude of the fall in rates of unassisted vaginal birth in association with a cascade of interventions in labour and interventions at birth particularly amongst women with no identified risk markers and having their first baby. This information may be useful for women wanting to explore other methods of influencing the course of labour and the management of pain in labour, especially in their endeavour to achieve a normal vaginal birth.

Temporal abstraction (TA) provides the means to instil domain knowledge into data analysis processes and allows transformation of low level numeric data to high level qualitative narratives. TA mechanisms have been primarily applied to uni-dimensional data sources equating to single patients in the clinical context. This paper presents a framework for multi-dimensional TA (MDTA) enabling analysis of data emanating from numerous patients to detect multiple conditions within the environment of neonatal intensive care. Patient agents which perform temporal reasoning upon patient data streams are based on the Event Calculus and an active ontology provides a central knowledge core where rules are stored and agent responses accumulated, thus permitting a level of multi-dimensionality within data abstraction processes. Facilitation of TA across a ward of patients offers the potential for early detection of debilitating conditions such as Sepsis, Pneumothorax and Periventricular Leukomalacia (PVL), which have been shown to exhibit advance indicators in physiological data. Preliminary prototyping for patient agents has begun with promising results and a schema for the active rule repository outlined.

This study documents the use of biodegradable poly(lactide-co-glycolide) (PLG) microspheres as a novel, injectable scaffold for cartilage tissue engineering. Chondrocytes were delivered via injection to the subcutaneous space of athymic mice in the presence and absence of PLG microspheres. Tissue formation was evaluated up to 8 weeks post-injection. Progressive cartilage formation was observed in samples containing microspheres. The presence of microspheres increased the quantity of tissue formed, the amount of glycosaminoglycan that accumulated, and the uniformity of type II collagen deposition. Microsphere composition influenced the growth of the tissue engineered cartilage. Higher molecular weight PLG resulted in a larger mass of cartilage formed and a higher content of proteoglycans. Microspheres comprised PLG with methyl ester end groups yielded increased tissue mass and matrix accumulation, but did not display homogenous matrix deposition. The microencapsulation of Mg(OH)2 had negative effects on tissue mass and matrix accumulation. Matrix accumulation, cell number, and tissue mass were unchanged by microsphere size, but larger microspheres increased the frequency of central necrosis in implants. The data herein reflect the promising utility of an injectable PLG-chondrocyte system for tissue engineering applications.

Objectives: To compare the predictive value of pH, base deficit and lactate for the occurrence of moderate-to-severe hypoxic ischaemic encephalopathy (HIE) and systemic complications of asphyxia in term infants with intrapartum asphyxia., Study Design: We retrospectively reviewed the records of 61 full-term neonates (> or =37 weeks gestation) suspected of having suffered from a significant degree of intrapartum asphyxia from a period of January 1997 to December 2001. The clinical signs of HIE, if any, were categorized using Sarnat and Sarnat classification as mild (stage 1), moderate (stage 2) or severe (stage 3). Base deficit, pH and plasma lactate levels were measured from indwelling arterial catheters within 1 hour after birth and thereafter alongwith every blood gas measurement. The results were correlated with the subsequent presence or absence of moderate-to-severe HIE by computing receiver operating characteristic curves., Results: The initial lactate levels were significantly higher (p=0.001) in neonates with moderate-to-severe HIE (mean+/-SD=11.09+/-4.6) as compared to those with mild or no HIE (mean+/-SD=7.1+/-4.7). Also, the lactate levels took longer to normalize in these babies. A plasma lactate concentration >7.5+/-mmol/l was associated with moderate-or-severe HIE with a sensitivity of 94% and specificity of 67%. The sensitivity and negative predictive value of lactate was greater than that of the pH or base deficit., Conclusions: The highest recorded lactate level in the first hour of life and serial measurements of lactate are important predictors of moderate-to-severe HIE.

Objective: To estimate the cost of "the cascade" of obstetric interventions introduced during labour for low risk women., Design: A cost formula derived from population data., Setting: New South Wales, Australia., Population: All 171,157 women having a live baby during 1996 and 1997., Methods: Four groups of interventions that occur during labour were identified. A cost model was constructed using the known age-adjusted rates for low risk women having one of three birth outcomes following these pre-specified interventions. Costs were based on statewide averages for the cost of labour and birth in hospital., Main Outcome Measures: The outcome measure is an "average cost unit per woman" for low risk women, predicted by the level of intervention during labour. Obstetric care is classified as either private obstetric care in a private or public hospital, or routine public hospital care., Results: The relative cost of birth increased by up to 50% for low risk primiparous women and up to 36% for low risk multiparous women as labour interventions accumulated. An epidural was associated with a sharp increase in cost of up to 32% for some primiparous low risk women, and up to 36% for some multiparous low risk women. Private obstetric care increased the overall relative cost by 9% for primiparous low risk women and 4% for multiparous low risk women., Conclusions: The initiation of a cascade of obstetric interventions during labour for low risk women is costly to the health system. Private obstetric care adds further to the cost of care for low risk women.

Spray freeze drying produces protein particles suitable for microencapsulation into polymeric microspheres intended for sustained release. Accessibility of encapsulated protein particles to the microsphere surface increases as the protein particle size is increased. Thus, it is desirable that the encapsulated protein particle size be minimized to limit initial release. We have investigated the effect of formulation on spray freeze-dried bovine serum albumin (BSA) as a model protein. Atomization conditions were fixed such that in the absence of excipient, the particle size of the sonicated powder was submicron, and there was substantial protein degradation (loss of monomer). Addition of low concentrations of surfactants (up to the CMC) or mannitol (up to the point where it tended to crystallize upon dehydration) resulted in partial stabilization without impacting particle size. Trehalose was successful in stabilizing the protein; however, there was a marked increase in particle size at the highest levels tested. Ammonium sulfate provided partial stabilization, but also tended to form crystals and increase particle size. FTIR measurements showed a loss of native secondary structure upon spray freeze drying that was ameliorated by addition of trehalose. Other excipients did not prevent structural perturbations. In general, stabilization of spray freeze-dried BSA was related to lowering of the specific surface area in the powder. A balance must be achieved when spray freeze drying proteins intended for encapsulation in sustained-release systems., (Copyright 2002 Wiley-Liss, Inc. and the American Pharmaceutical Association J Pharm Sci 91:388-395, 2002)

The objective of this study was to examine the effects of formulation and process variables on particle size and other characteristics of a spray-dried model protein, bovine serum albumin (BSA), using a partial factorial design for experiments. Formulation variables tested include concentration and zinc:protein complexation ratio. Process variables explored were inlet temperature, liquid feed rate, drying air flow rate, and atomizing nitrogen pressure on a lab-scale spray dryer. Statistical data analysis was used to determine F ratios for each of the inputs, which provided a means of ranking the importance of variables relative to one another for each powder characteristic of interest. It was found that protein concentration and atomizing nitrogen pressure had the greatest effects on the particle size of the protein powder. For determining product yield, results showed that protein concentration was the critical variable. Finally, the outlet temperature was mostly influenced by inlet temperature and liquid feed rate. Mathematical models based on these input-output relationships were constructed; these models provide insight into some of the controllable variables of the spray-drying process.

Bergmann's rule states that, within species of mammals, individuals tend to be larger in cooler environments. However, the validity of the rule has been debated. We examined the relationship between size and latitude as well as size and temperature within various species of mammals. We also tested the idea that smaller mammals follow Bergmann's rule more strongly than larger mammals, as expected if heat conservation is the cause of the rule. When all studies were included, the percentage of species showing a positive correlation between size and latitude was significantly >50% (78 of 110 species). Similarly, the percentage of species showing a negative correlation between size and temperature was significantly >50% (48 of 64). Analyses using only significant studies or only studies that sampled extensively also support Bergmann's rule. The size-latitude and size-temperature trends were consistent within all orders and most families for which data are available. We did not find support for the hypothesis that smaller mammals conform more strongly to Bergmann's rule than larger mammals. Thus, we found broad support for Bergmann's rule as a general trend for mammals; however, our analyses do not support heat conservation as the explanation.