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OBJECTIVE: To construct international ultrasound-based standards for fetal cerebellar growth and Sylvian fissure maturation. METHODS: Healthy, well nourished pregnant women, enrolled at

Background Gestational hypertensive and acute hypotensive disorders are associated with maternal morbidity and mortality worldwide. However, physiological blood pressure changes in pregnancy are insufficiently defined. We describe blood pressure changes across healthy pregnancies from the International Fetal and Newborn Growth Consortium for the 21st Century (INTERGROWTH-21st) Fetal Growth Longitudinal Study (FGLS) to produce international, gestational age-specific, smoothed centiles (third, 10th, 50th, 90th, and 97th) for blood pressure. Methods and findings Secondary analysis of a prospective, longitudinal, observational cohort study (2009 to 2016) was conducted across 8 diverse urban areas in Brazil, China, India, Italy, Kenya, Oman, the United Kingdom, and the United States of America. We enrolled healthy women at low risk of pregnancy complications. We measured blood pressure using standardised methodology and validated equipment at enrolment at 14 mmHg or diastolic blood pressure by >11 mmHg in fewer than 10% of women at any gestational age. Fewer than 10% of women increased their systolic blood pressure by >24 mmHg or diastolic blood pressure by >18 mmHg at any gestational age. The study’s main limitations were the unavailability of prepregnancy blood pressure values and inability to explore circadian effects because time of day was not recorded for the blood pressure measurements. Conclusions Our findings provide international, gestational age-specific centiles and limits of acceptable change to facilitate earlier recognition of deteriorating health in pregnant women. These centiles challenge the idea of a clinically significant midpregnancy drop in blood pressure., Lauren Green and colleagues study blood pressure in pregnant women across a range of countries., Author summary Why was this study done? Internationally applicable gestational age-specific centiles for blood pressure are needed in clinical practice to determine when women have left the “normal” range. It is uncertain whether clinically significant decreases in blood pressure occur between early and midpregnancy. What did the researchers do and find? We estimated international gestational age-specific blood pressure centiles using longitudinal blood pressure data provided by women from 8 countries who took part in the International Fetal and Newborn Growth Consortium for the 21st Century (INTERGROWTH-21st) Project. On average, systolic blood pressure rose by around 8 mmHg between 12 and 40 weeks’ gestation, with no decrease in midpregnancy. Diastolic blood pressure decreased slightly (by around 0.6 mmHg) between 12 and 19 weeks, rising thereafter until 40 weeks’ gestation. At any gestational age, systolic blood pressure fell by >14 mmHg and diastolic blood pressure by >11 mmHg from baseline in fewer than 10% of women. Fewer than 10% of women increased their systolic blood pressure by >24 mmHg or diastolic blood pressure by >18 mmHg at any gestational age. What do these findings mean? Our findings challenge the frequently quoted midpregnancy blood pressure decrease, advocating for a higher index of clinical suspicion when a woman presents with a “lower than booking” blood pressure, especially in late pregnancy. We show the limits for acceptable change in blood pressure during healthy pregnancy, which should help clinicians determine patients with abnormal blood pressure rises and falls.

Summary Background Preterm birth is a major global health challenge, the leading cause of death in children under 5 years of age, and a key measure of a population's general health and nutritional status. Current clinical methods of estimating fetal gestational age are often inaccurate. For example, between 20 and 30 weeks of gestation, the width of the 95% prediction interval around the actual gestational age is estimated to be 18–36 days, even when the best ultrasound estimates are used. The aims of this study are to improve estimates of fetal gestational age and provide personalised predictions of future growth. Methods Using ultrasound-derived, fetal biometric data, we developed a machine learning approach to accurately estimate gestational age. The accuracy of the method is determined by reference to exactly known facts pertaining to each fetus—specifically, intervals between ultrasound visits—rather than the date of the mother's last menstrual period. The data stem from a sample of healthy, well-nourished participants in a large, multicentre, population-based study, the International Fetal and Newborn Growth Consortium for the 21st Century (INTERGROWTH-21st). The generalisability of the algorithm is shown with data from a different and more heterogeneous population (INTERBIO-21st Fetal Study). Findings In the context of two large datasets, we estimated gestational age between 20 and 30 weeks of gestation with 95% confidence to within 3 days, using measurements made in a 10-week window spanning the second and third trimesters. Fetal gestational age can thus be estimated in the 20–30 weeks gestational age window with a prediction interval 3–5 times better than with any previous algorithm. This will enable improved management of individual pregnancies. 6-week forecasts of the growth trajectory for a given fetus are accurate to within 7 days. This will help identify at-risk fetuses more accurately than currently possible. At population level, the higher accuracy is expected to improve fetal growth charts and population health assessments. Interpretation Machine learning can circumvent long-standing limitations in determining fetal gestational age and future growth trajectory, without recourse to often inaccurately known information, such as the date of the mother's last menstrual period. Using this algorithm in clinical practice could facilitate the management of individual pregnancies and improve population-level health. Upon publication of this study, the algorithm for gestational age estimates will be provided for research purposes free of charge via a web portal. Funding Bill & Melinda Gates Foundation, Office of Science (US Department of Energy), US National Science Foundation, and National Institute for Health Research Oxford Biomedical Research Centre.

We studied neurodevelopmental outcomes and behaviours in healthy 2-year old children (N = 1306) from Brazil, India, Italy, Kenya and the UK participating in the INTERGROWTH-21st Project. There was a positive independent relationship of duration of exclusive breastfeeding (EBF) and age at weaning with gross motor development, vision and autonomic physical activities, most evident if children were exclusively breastfed for ≥7 months or weaned at ≥7 months. There was no association with cognition, language or behaviour. Children exclusively breastfed from birth to 6 months had, in a dose-effect pattern, adjusting for confounding factors, higher scores for “emotional reactivity”. The positive effect of EBF and age at weaning on gross motor, running and climbing scores was strongest among children with the highest scores in maternal closeness proxy indicators. EBF, late weaning and maternal closeness, associated with advanced motor and vision maturation, independently influence autonomous behaviours in healthy children.

ObjectivesTo describe the construction of the international INTERGROWTH-21st Neurodevelopment Assessment (INTER-NDA) standards for child development at 2 years by reporting the cognitive, language, motor and behaviour outcomes in optimally healthy and nourished children in the INTERGROWTH-21st Project.DesignPopulation-based cohort study, the INTERGROWTH-21st Project.SettingBrazil, India, Italy, Kenya and the UK.Participants1181 children prospectively recruited from early fetal life according to the prescriptive WHO approach, and confirmed to be at low risk of adverse perinatal and postnatal outcomes.Primary measuresScaled INTER-NDA domain scores for cognition, language, fine and gross motor skills and behaviour; vision outcomes measured on the Cardiff tests; attentional problems and emotional reactivity measured on the respective subscales of the preschool Child Behaviour Checklist; and the age of acquisition of the WHO gross motor milestones.ResultsScaled INTER-NDA domain scores are presented as centiles, which were constructed according to the prescriptive WHO approach and excluded children born preterm and those with significant postnatal/neurological morbidity. For all domains, except negative behaviour, higher scores reflect better outcomes and the threshold for normality was defined as ≥10th centile. For the INTER-NDA’s cognitive, fine motor, gross motor, language and positive behaviour domains these are ≥38.5, ≥25.7, ≥51.7, ≥17.8 and ≥51.4, respectively. The threshold for normality for the INTER-NDA’s negative behaviour domain is ≤50.0, that is, ≤90th centile. At 22–30 months of age, the cohort overlapped with the WHO motor milestone centiles, showed low postnatal morbidity (ConclusionsFrom this large, healthy and well-nourished, international cohort, we have constructed, using the WHO prescriptive methodology, international INTER-NDA standards for child development at 2 years of age. Standards, rather than references, are recommended for population-level screening and the identification of children at risk of adverse outcomes.

Objective: This study aims to outline the progress of midwifery-related policies in contemporary and modern China as well as the obstacles in this process, and to provide recommendations for policy makers in the establishment of Chinese midwifery policies, ultimately promoting the development of midwifery in China. Background and introduction Policy plays an increasingly important role in midwifery development, particularly needed in modern China. A review of policies of midwifery could help policy makers develop effective strategies to address current problems in China, including the insufficient numbers of midwives, the shrinking of responsibility and the degradation of midwives’ competency. Methods The Policy Triangle was used to examine through literature the laws and regulations regarding midwifery from 1928 in China and was conducted from April to September in 2013. This was followed by insider interviews with two senior policy makers from the National Health Commission to explain nursing policy progress, thereby identifying the reasons why midwifery has developed more slowly than nursing. Results The development of midwifery in China could be classified into four stages: (1) the beginning period (1928–1949), beginning with the first midwifery rules; (2) the development period (1949–1979), in which the quality and quantity of midwives were significant; (3) the unclear positioning period (1979–2008), without clear midwifery policy; and (4) the subordination to nursing period (2008–present), with the Nurse Byelaw 2008 stating that midwives must apply for nursing licenses. Discussion The main factors influencing midwifery policies are: (1) social background, such as the changes of different governments and health care reform, and (2) the powers of the actors. Currently, it is an appropriate time to develop strategies for policy makers to facilitate midwifery development in China. Conclusions and Implications for Health Policy Midwifery policy should be independently included in the frame of national medical industry reform because midwives are an indispensable part of the health care workforce. In-depth research should be conducted to confirm the position of midwifery in China to ensure its sustainable development.

Objective To create prescriptive growth standards for five fetal brain structures, measured using ultrasound, in healthy, well-nourished women at low risk of impaired fetal growth and poor perinatal outcome, taking part in the Fetal Growth Longitudinal Study (FGLS) of the INTERGROWTH-21st Project. Methods This was a complementary analysis of a large, population-based, multicenter, longitudinal study. The sample analyzed was selected randomly from the overall FGLS population, ensuring an equal distribution among the eight diverse participating sites and of three-dimensional (3D) ultrasound volumes across pregnancy (range: 15-36 weeks' gestation). We measured, in planes reconstructed from 3D ultrasound volumes of the fetal head at different timepoints in pregnancy, the size of the parieto-occipital fissure (POF), Sylvian fissure (SF), anterior horn of the lateral ventricle, atrium of the posterior horn of the lateral ventricle (PV) and cisterna magna (CM). Fractional polynomials were used to construct the standards. Growth and development of the infants were assessed at 1 and 2 years of age to confirm their adequacy for constructing international standards. Results From the entire FGLS cohort of 4321 women, 451 (10.4%) were selected at random. After exclusions, 3D ultrasound volumes from 442 fetuses born without a congenital malformation were used to create the charts. The fetal brain structures of interest were identified in 90% of cases. All structures, except the PV, showed increasing size with gestational age, and the size of the POF, SF, PV and CM showed increasing variability. The 3rd , 5th , 50th , 95th and 97th smoothed centiles are presented. The 5th centiles for the POF and SF were 3.1 mm and 4.7 mm at 22 weeks' gestation and 4.6 mm and 9.9 mm at 32 weeks, respectively. The 95th centiles for the PV and CM were 8.5 mm and 7.5 mm at 22 weeks and 8.6 mm and 9.5 mm at 32 weeks, respectively. Conclusions We have produced prescriptive size standards for fetal brain structures based on prospectively enrolled pregnancies at low risk of abnormal outcome. We recommend these as international standards for the assessment of measurements obtained using ultrasound from fetal brain structures. © 2020 Authors. Ultrasound in Obstetrics & Gynecology published by John Wiley & Sons Ltd on behalf of International Society of Ultrasound in Obstetrics and Gynecology.

Background: Preterm birth is a major global health challenge, and the leading cause of death in children under 5 years old 1. It is also a key measure of a population's general health and nutritional status 2. Current clinical methods of estimating fetal gestational age are often inaccurate; between 20 and 30 weeks of gestation, even the best ultrasound estimates have uncertainties of 9 - 18 days 3 (full widths of 18 - 36 days). Accurate estimates of fetal gestational age and personalized predictions of future growth can substantially improve the management of individual pregnancies and population-level health. Methods: Using ultrasound-derived, fetal biometric data, we present a novel machine-learning approach to accurately estimate the gestational age, and predict the future growth trajectory of each fetus. The accuracy of the method is determined by reference to exactly known facts pertaining to each fetus, rather than the start of the mother's last menstrual cycle. The data stem from a sample of healthy, well-nourished participants in a large, multicenter, population-based study, INTERGROWTH-21st 4. The generalizability of the algorithm is demonstrated with data from a different and more heterogeneous population (INTERBIO-21st). No new facilities are needed beyond those routinely available in clinical settings. Findings: We estimate the fetal gestational age to within 3 days, using measurements made in a 10-week window spanning the second and third trimesters. Fetal gestational age can thus be estimated into the third trimester with an accuracy of 3 days, which is 300% to 500% better than possible with any previous algorithm 5. This will enable improved management of individual pregnancies. Personalized forecasts of future fetal growth are also, for the first time, available. Six-week forecasts of the growth trajectory for a given fetus are accurate to within 7 days. This will help identify at-risk fetuses significantly more accurately than currently possible. At population level, the much higher accuracy will improve fetal growth charts and population health assessments. Upon publication of this paper, the new algorithm can be used free of charge via a web portal. Interpretation: Modern machine-learning can circumvent longstanding limitations in determining fetal gestational age and future growth trajectory without recourse to often inaccurately-known information, such as the date of the mother's last menstrual period. Our approach can be extended to other types of fetal-related data, such as measurements of cell-free RNA (cfRNA) transcripts in maternal blood 6. More generally, the approach has the potential to provide accurate forecasts of disease progression from spot measurements of the relevant biomarkers. Funding Statement: Bill & Melinda Gates Foundation; US Department of Energy, Office of Science, Basic Energy Sciences award DE-SC0002164 (underlying dynamical techniques); US National Science Foundation awards STC 1231306 (underlying data analytical techniques) and 1551489 (underlying analytical models); and National Institute for Health Research (NIHR) Oxford Biomedical Research Centre (BRC). Declaration of Interests: The authors stated: "None reported." Ethics Approval Statement: The INTERGROWTH-21st 255 Project was approved by the Oxfordshire Research Ethics Committee “C” (reference: 08/H0606/139), and the research ethics committees of the individual institutions and the regional health authorities where the project was implemented. Written informed consent was obtained from all participants.

Objective To describe patterns in maternal gestational weight gain (GWG) in healthy pregnancies with good maternal and perinatal outcomes. Design Prospective longitudinal observational study. Setting Eight geographically diverse urban regions in Brazil, China, India, Italy, Kenya, Oman, United Kingdom, and United States, April 2009 to March 2014. Participants Healthy, well nourished, and educated women enrolled in the Fetal Growth Longitudinal Study component of the INTERGROWTH-21st Project, who had a body mass index (BMI) of 18.50-24.99 in the first trimester of pregnancy. Main outcome measures Maternal weight measured with standardised methods and identical equipment every five weeks (plus/minus one week) from the first antenatal visit ( Results 13 108 pregnant women at Conclusions Weight gain in pregnancy is similar across the eight populations studied. Therefore, the standards generated in this study of healthy, well nourished women may be used to guide recommendations on optimal gestational weight gain worldwide.

The purpose of the INTERGROWTH-21

OBJECTIVES: To assess a comprehensive package of ultrasound quality control in a large multicentre study of fetal growth - the Fetal Growth Longitudinal Study of the INTERGROWTH-21(st) Project. METHODS: We performed quality control (QC) measures on 20,313 ultrasound scan images taken prospectively from 4,321 fetuses at 14-41 weeks' gestation in eight geographical locations. At the time of each ultrasound examination, three fetal biometric variables were measured in triplicate on separately generated images: head circumference (HC), abdominal circumference (AC) and femur length (FL). All measurements were taken in a blinded fashion. QC had two elements: 1) qualitative QC: visual assessment by sonographers at each study site of their images based on specific criteria with 10% of images being re-assessed at the Oxford-based Ultrasound Quality Unit (compared using an adjusted kappa statistic), and 2) quantitative QC: measurement data were assessed by (a) comparing the first, second and third measurement (intraobserver variability); (b) re-measurement of caliper replacement in 10% (interobserver variability), both by Bland-Altman plots, and (c) plotting frequency histograms of the SDs of triplicate measurements and assessing how many were above or below 2SDs of the expected distribution. The system allowed the sonographers' performance to be regularly monitored. RESULTS: A high level of agreement between the self- and external scoring was demonstrated for all measurements (kappa = 0.99 [95% confidence interval: 0.98, 0.99] for HC, 0.98 [0.97, 0.99] for AC, and 0.96 [0.95, 0.98] for FL. Intraobserver variability (95% limits of agreement (LoA)) of ultrasound measures for HC, AC and FL were ±3%, ±6% and ±6%, respectively; the corresponding values for interobserver variability were ±4%, ±6% and ±6%. The SD distribution of triplicate measurements for all biometric variables showed excessive variability for three of 31 sonographers, allowing prompt identification and retraining. CONCLUSIONS: Qualitative and quantitative QC monitoring was feasible and highly reproducible in a large multicentre research study, which facilitated the production of high-quality ultrasound images. We recommend that the QC system we developed is implemented in future research studies and clinical practice.

Fetal growth assessment is important to identify fetuses with abnormal fetal growth that are at increased risk of perinatal morbidity and mortality. Serial measurement of symphysis-fundal height (SFH) is the recommended, inexpensive, and first-level screening tool in both low- and high-risk pregnancies. However, SFH measurements show a wide range of sensitivities for detecting small for gestational age (SGA) owing to the different measurement methods, charts, and thresholds used to perform an ultrasound scan and the use of uncorroborated menstrual dates that can cause errors in dating and can lead to overestimating the length of gestation. A prospective longitudinal observational study, the Fetal Growth Longitudinal Study, one of the main components of the INTERGROWTH-21st Project, was conducted on healthy, well-nourished women to develop international SFH standards to improve antenatal care. Of the 13,108 women screened in the first trimester, 4607 met study criteria, and of these, 4321 (93.8%) delivered live singletons without congenital malformations or complications. The median number of SFH measurements in all women was 5.0 (range, 1–7); 3976 (92.0%) women had 4 or more measurements. Analysis of the duplicate SFH measurements obtained from all women showed that the 95% limits of agreement were approximately 1.5 cm. The international standards developed through this study overcome many of the methodological limitations of SFH measurement by reducing the wide range in sensitivity for the detection of SGA and should reduce the risk of failing to diagnose restricted and excessive fetal growth and help in comparisons across populations. The new international SFH standards in combination with standardized measurement methodology are recommended to improve clinical practice.

Background We aimed to describe newborn body composition and identify which anthropometric ratio (weight/length; BMI; or ponderal index, PI) best predicts fat mass (FM) and fat-free mass (FFM). Methods Air-displacement plethysmography (PEA POD) was used to estimate FM, FFM, and body fat percentage (BF%). Associations between FFM, FM, and BF% and weight/length, BMI, and PI were evaluated in 1,019 newborns using multivariate regression analysis. Charts for FM, FFM, and BF% were generated using a prescriptive subsample (n=247). Standards for the best-predicting anthropometric ratio were calculated utilizing the same population used for the INTERGROWTH-21st Newborn Size Standards (n=20,479). Results FFM and FM increased consistently during late pregnancy. Differential FM, BF%, and FFM patterns were observed for those born preterm (34+0−36+6 weeks’ gestation) and with impaired intrauterine growth. Weight/length by gestational age (GA) was a better predictor of FFM and FM (adjusted R2=0.92 and 0.71, respectively) than BMI or PI, independent of sex, GA, and timing of measurement. Results were almost identical when only preterm newborns were studied. We present sex-specific centiles for weight/length ratio for GA. Conclusions Weight/length best predicts newborn FFM and FM. There are differential FM, FFM, and BF% patterns by sex, GA, and size at birth.

Background An unnecessary Caesarean section (CS) can cause increased maternal and perinatal morbidity and other adverse short- and long-term outcomes. However, countries worldwide have witnessed an increasing trend toward the use of CS. Our objectives were to explore the influencing factors associated with the mode of birth among childbearing women in Hunan Province and to provide evidence and suggestions for the improvement and further understanding of vaginal birth (VB) in China. Methods A total of 977 childbearing women (375 pregnant women and 602 mothers of infants) were enrolled in this study using a two-stage cluster sampling method, and a self-administered questionnaire was used to collect data relating to the mode of birth. A t-test and χ2-test were used to analyse the differences between groups, and logistic regression analysis was used to explore the factors that influenced the mode of birth. Results The VB ratio was 46.2 %, while the CS ratio was 53.8 % in Hunan Province. Among women whose preference was VB, only 69.4 % gave birth by VB. Among women whose preference was CS, 98.1 % gave birth by CS. The top four reasons for preferring CS were a lack of confidence in VB (37.3 %), an abnormality in the prenatal examination (36.6 %), the notion that the baby would suffer fewer risks (34.8 %) and the fear of pain from VB (32.7 %). Age, prenatal examination, and doctors’ suggestion were significantly associated with women’s mode of birth preference, while place of household registration, husband’s preference, prenatal examination and doctors’ suggestion had a significant influence on women who changed their choice from VB to CS. Conclusions The percentage of CS in Hunan was extremely high. Medical factors, such as abnormalities in prenatal examinations, and non-medical factors, such as a lack of confidence in VB, the fear of pain during VB, the desire to select the time of birth and healthy birth systems, should be seriously considered. Targeted health promotion interventions should be implemented to improve the performance of VB. Electronic supplementary material The online version of this article (doi:10.1186/s12884-016-0897-9) contains supplementary material, which is available to authorized users.

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Importance Preterm birth has been difficult to study and prevent because of its complex syndromic nature. Objective To identify phenotypes of preterm delivery syndrome in the Newborn Cross-Sectional Study of the INTERGROWTH-21st Project. Design, Setting, and Participants A population-based, multiethnic, cross-sectional study conducted at 8 geographically demarcated sites in Brazil, China, India, Italy, Kenya, Oman, the United Kingdom, and the United States. A total of 60 058 births over a 12-month fixed period between April 27, 2009, and March 2, 2014. Of these, 53 871 had an ultrasonography estimate of gestational age, among which 5828 were preterm births (10.8%). Pregnancies were prospectively studied using a standardized data collection and online data management system. Newborns had anthropometric and clinical examinations using standardized methods and identical equipment and were followed up until hospital discharge. Main Outcomes and Measures The main study outcomes were clusters of preterm phenotypes and for each cluster, we analyzed signs of presentation at hospital admission, admission rates for neonatal intensive care for 7 days or more, and neonatal mortality rates. Results Twelve preterm birth clusters were identified using our conceptual framework. Eleven consisted of combinations of conditions known to be associated with preterm birth, 10 of which were dominated by a single condition. However, the most common single cluster (30.0% of the total preterm cases; n = 1747) was not associated with any severe maternal, fetal, or placental condition that was clinically detectable based on the information available; within this cluster, many cases were caregiver initiated. Only 22% (n = 1284) of all the preterm births occurred spontaneously without any of these severe conditions. Maternal presentation on hospital admission, newborn anthropometry, and risk for death before hospital discharge or admission for 7 or more days to a neonatal intensive care unit, none of which were used to construct the clusters, also differed according to the identified phenotypes. The prevalence of preterm birth ranged from 8.2% in Muscat, Oman, and Oxford, England, to 16.6% in Seattle, Washington. Conclusions and Relevance We identified 12 preterm birth phenotypes associated with different patterns of neonatal outcomes. In 22% of all preterm births, parturition started spontaneously and was not associated with any of the phenotypic conditions considered. We believe these results contribute to an improved understanding of this complex syndrome and provide an empirical basis to focus research on a more homogenous set of phenotypes.

Objectives There are no international standards for relating fetal crown–rump length (CRL) to gestational age (GA), and most existing charts have considerable methodological limitations. The INTERGROWTH-21st Project aimed to produce the first international standards for early fetal size and ultrasound dating of pregnancy based on CRL measurement. Methods Urban areas in eight geographically diverse countries that met strict eligibility criteria were selected for the prospective, population-based recruitment, between 9 + 0 and 13 + 6 weeks' gestation, of healthy well-nourished women with singleton pregnancies at low risk of fetal growth impairment. GA was calculated on the basis of a certain last menstrual period, regular menstrual cycle and lack of hormonal medication or breastfeeding in the preceding 2 months. CRL was measured using strict protocols and quality-control measures. All women were followed up throughout pregnancy until delivery and hospital discharge. Cases of neonatal and fetal death, severe pregnancy complications and congenital abnormalities were excluded from the study. Results A total of 4607 women were enrolled in the Fetal Growth Longitudinal Study, one of the three main components of the INTERGROWTH-21st Project, of whom 4321 had a live singleton birth in the absence of severe maternal conditions or congenital abnormalities detected by ultrasound or at birth. The CRL was measured in 56 women at

Background Disparity in maternal mortality exists between rural–urban migrant and urban resident women in China, but little research has provided evidence for related policy development. The objective of this study was to identify associations with and risks for maternal death among rural–urban migrant women in order to improve health services for migrant women and reduce maternal mortality in China. Methods We conducted a prospective case–control study in urban areas of Guangdong, Zhejiang and Fujian provinces and Beijing municipality. In each, migrant women who died between July 1, 2010 and October 1, 2011 were identified through reports from China’s Maternal and Child Mortality Surveillance System. For each, four matched controls were selected from migrant women who delivered in local hospitals during the same period. We compared socio-demographic characteristics, health status and health service variables between cases and controls, and used bivariate and multivariate conditional logistic regression analyses to determine associations with and risk factors for maternal death. Results 109 cases and 436 controls were assessed. Family income