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Background: People whose singleton pregnancy is affected by hypertensive disorders of pregnancy (HDP) are at risk of future cardiovascular disease. It is unclear, however, whether this association can be extrapolated to twin pregnancies. We aimed to compare the association between HDP and future cardiovascular disease after twin and singleton pregnancies.Methods: We conducted a population-based retrospective cohort study that included nulliparous people in Ontario, Canada, 1992-2017. We compared the future risk of cardiovascular disease among pregnant people from the following 4 groups: those who delivered a singleton without HDP (referent) and with HDP, and those who delivered twins either with or without HDP.Results: The populations of the 4 groups were as follows: 1 431 651 pregnant people in the singleton birth without HDP group; 98 631 singleton birth with HDP; 21 046 twin birth without HDP; and 4283 twin birth with HDP. The median duration of follow-up was 13 (interquartile range 7-20) years. The incidence rate of cardiovascular disease was lowest among those with a singleton or twin birth without HDP (0.72 and 0.74 per 1000 person-years, respectively). Compared with people with a singleton birth without HDP, the risk of cardiovascular disease was highest among those with a singleton birth and HDP (1.47 per 1000 person-years; adjusted hazard ratio [HR] 1.81 [95% confidence interval (CI) 1.72-1.90]), followed by people with a twin pregnancy and HDP (1.07 per 1000 person-years; adjusted HR 1.36 [95% CI 1.04-1.77]). The risk of the primary outcome after a twin pregnancy with HDP was lower than that after a singleton pregnancy with HDP (adjusted HR 0.74 [95% CI 0.57-0.97]), when compared directly.Interpretation: In a twin pregnancy, HDP are weaker risk factors for postpartum cardiovascular disease than in a singleton pregnancy. [ABSTRACT FROM AUTHOR]

Background: Accurate identification of maternal deaths is paramount for audit and policy purposes. Our aim was to determine the accuracy and completeness of data on maternal deaths in hospital and those recorded on a death certificate, and the level of agreement between the 2 data sources. Methods: We conducted a retrospective population-based study using data for Ontario, Canada, from Apr. 1, 2002, to Dec. 31, 2015. We used Canadian Institute for Health Information (CIHI) databases to identify deaths during inpatient, emergency department and same-day surgery encounters. We captured Vital Statistics deaths in the Office of the Registrar General, Deaths (ORGD) data set. Deaths were considered within 42 days and within 365 days after a pregnancy outcome (live birth, miscarriage, ectopic pregnancy or induced abortion) for all multiple and singleton pregnancies. We calculated agreement statistics and 95% confidence intervals (CIs). Results: Among 1 679 455 live births and stillbirths, 398 pregnancy-related deaths in the ORGD data set were mapped to a birth in CIHI databases, and 77 (16.2%) were not. Among 2 039 849 recognized pregnancies, 534 pregnancy-related deaths in the ORGD data set were linked to CIHI records, and 68 (11.3%) were not. Among live births and stillbirths, after pregnancy-related deaths in the ORGD data set not matched to a maternal death in the CIHI databases were removed, concordance measures between CIHI and ORGD records for maternal death within 42 days after delivery included a κ value of 0.87 (95% CI 0.82–0.91) and positive percent agreement of 0.88 (95% CI 0.83–0.94). The corresponding measures were similar for maternal death within 42 days after the end of a recognized pregnancy. When unlinked pregnancy-related deaths in the ORGD data set were retained, agreement measures declined for death within 42 days after a live birth or stillbirth (κ = 0.68, 95% CI 0.62–0.74). For maternal death within 365 days after a live birth or stillbirth, or after the end of a recognized pregnancy, the concordance statistics were generally favourable when unlinked pregnancy-related deaths in the ORGD data set were removed but were substantially declined when they were retained. Interpretation: Maternal mortality cannot be ascertained solely with the use of hospital data, including beyond 42 days after the end of pregnancy. To improve linkage, we propose including health insurance numbers on provincial and territorial medical death certificates. [ABSTRACT FROM AUTHOR]

Background: Different primary care delivery models exist for mothers and their infants. We examined whether primary care system performance measures differed when mother-infant dyads received primary care from the same or different providers.Methods: We conducted a population-based cohort study using Ontario health administrative data from 2004 to 2016. We included primiparous women and their singleton term infants and classified the primary care practitioners who provided the majority of care to the infant and the mother as concordant (same family physician for both; reference group), discordant (a different family physician for each) or pediatrician (pediatrician for the child, family physician for the mother). The primary outcome was nonobstetric maternal hospital admissions between 42 days and 2 years after delivery.Results: Among 481 721 mother-child pairs, 239 033 (49.6%) received concordant care, 114 006 (23.7%) received discordant care, and 128 682 (26.7%) received pediatrician care. Mothers in the pediatrician group were older and had greater comorbidity. Relative to concordant care, maternal nonobstetric hospital admissions occurred similarly under discordant care (adjusted odds ratio [OR] 1.00, 95% confidence interval [CI] 0.96-1.04) and in the pediatrician group (adjusted OR 0.99, 95% CI 0.95-1.02). Maternal deaths were similar under discordant care (adjusted OR 1.00, 95% CI 0.62-1.63) but lower in the pediatrician group (adjusted OR 0.55, 95% CI 0.34-0.89). Maternal primary care visits were lower in both the discordant group (adjusted relative risk [RR] 0.68, 95% CI 0.68-0.69) and the pediatrician group (adjusted RR 0.75, 95% CI 0.75-0.76). Healthy children were more likely to miss the enhanced 18-month well-baby visit under discordant care (adjusted OR 1.06, 95% CI 1.03-1.09) but less likely to miss this visit under pediatrician care (adjusted OR 0.47, 95% CI 0.46-0.49).Interpretation: Concordant care provided to a new mother and her infant by the same family physician was not associated with better primary care health system performance. The reason that pediatric primary care is associated with better maternal and child outcomes remains to be determined. [ABSTRACT FROM AUTHOR]

Background: Prepregnancy kidney dysfunction has been associated with preterm birth, which is the leading cause of neonatal morbidity and mortality; however, the relation is not well understood. We determined the risk of preterm birth in women with prepregnancy kidney dysfunction, defined using pregnancy-specific serum creatinine cut points.Methods: This population-based cohort study in the province of Ontario, Canada, involved women aged 16 to 50 years who had a singleton birth between 2006 and 2016 and measurement of serum creatinine within 10 weeks preceding their estimated conception date. The exposure was abnormally elevated prepregnancy serum creatinine, defined as greater than the 95th percentile (> 77 μmol/L), a value derived from a population-based sample of women without known kidney disease who became pregnant soon after the measurement was obtained. The main outcome was any preterm birth from 23 to 36 weeks' gestation. Secondary outcomes included provider-initiated preterm birth before 37 weeks' gestation and spontaneous preterm birth before 37 weeks.Results: Among 55 946 pregnancies, preterm birth before 37 weeks' gestation occurred in 3956 women (7.1%). The risk of preterm birth before 37 weeks was higher among women with prepregnancy creatinine above the 95th percentile, relative to those with prepregnancy creatinine at or below the 95th percentile (9.1% v. 7.0%; adjusted relative risk [RR] 1.23, 95% confidence interval [CI] 1.09 to 1.38). The effect was significant for provider-initiated preterm birth (adjusted RR 1.30, 95% CI 1.11 to 1.52) but not for spontaneous preterm birth (adjusted RR 1.12, 95% CI 0.91 to 1.37).Interpretation: Given that prepregnancy kidney dysfunction conferred an increased risk of preterm birth, measurement of serum creatinine (a relatively inexpensive blood test) may form part of the assessment of risk for preterm birth among those planning pregnancy. [ABSTRACT FROM AUTHOR]

Background: Peripregnancy emergency department use may be common, but data specific to health care systems like that in Canada are lacking. As prior research was limited to livebirths, omitting pregnancies ending in miscarriage or induced abortion, the current study quantified and characterized emergency department use among women in Ontario with a recognized pregnancy. Methods: This retrospective population-based cohort study included all recognized pregnancies among Ontario residents aged 10–55 years with an estimated date of conception between Apr. 1, 2002, and Mar. 31, 2017. We defined peripregnancy emergency department use as any emergency department visit during pregnancy or within 42 days after pregnancy. We used modified Poisson regression with a robust error variance to generate relative risks (RRs) and 95% confidence intervals (CIs) for the outcome of any peripregnancy emergency department use in association with maternal age, parity, residential income quintile, location of residence, immigrant status, antenatal care provider and number of comorbidities within 120 days before the clinical start of the pregnancy (expressed as total number of Aggregated Diagnosis Groups [ADGs] obtained with the Johns Hopkins Adjusted Clinical Group System). All RRs, except for number of comorbidities, were further adjusted for number of ADGs. Results: Peripregnancy emergency department use occurred in 1 075 991 (39.4%) of 2 728 236 recognized pregnancies, including 35.8% of livebirths, 47.3% of stillbirths, 73.7% of miscarriages and 84.8% of threatened abortions. A peripregnancy emergency department visit was more likely among women who were less than 25 years of age (adjusted RR 1.16, 95% CI 1.16–1.17), were nulliparous (adjusted RR 1.13, 95% CI 1.13–1.13), resided in the lowest income quintile area (adjusted RR 1.16, 95% CI 1.15–1.16) or in a rural area (adjusted RR 1.50, 95% CI 1.50–1.51), were Canadian-born (adjusted RR 1.22, 95% CI 1.22–1.23), were not seen by an obstetrician (adjusted RR 1.66, 95% CI 1.54–1.80) or had a greater number of ADGs. Emergency department use peaked in the first trimester and in the first week postpartum. Compared to women residing in urban areas, those residing in rural areas had an odds ratio (OR) of 3.44 (95% CI 3.39–3.49) for 3 or more emergency department visits. Women with 3–4 (OR 1.99, 95% CI 1.97–2.01), 5–6 (OR 3.55, 95% CI 3.49–3.61), or 7 or more (OR 7.59, 95% CI 7.39–7.78) prepregnancy comorbidities were more likely to have 3 or more peripregnancy emergency department visits than were those with 2 or fewer comorbidities. Interpretation: Peripregnancy emergency department use occurred in nearly 40% of pregnancies, notably in the first trimester and early in the postpartum period. Efforts are needed to streamline rapid access to ambulatory obstetric care during these peak periods, when women are susceptible to miscarriage or a complication after a livebirth. [ABSTRACT FROM AUTHOR]

Background: Induced abortion is a common procedure performed by physicians with varying degrees of clinical experience. We aimed to determine whether a physician's procedure volume influences complications after induced abortion.Methods: We obtained population-based retrospective data on surgically induced abortion procedures in Ontario between 2003 and 2015 from Ontario health administrative databases held at ICES. Physician procedure volume was defined as the number of surgically induced abortions performed in the 1-year period preceding the index procedure date, categorized as low (< 10th percentile of yearly volume) or higher (≥ 10th percentile). The primary outcome was a severe adverse event (maternal end organ damage, severe maternal morbidity, intensive care unit admission or death) within 42 days after an induced abortion. The secondary outcome was any adverse event within 42 days.Results: Among 529 141 surgical abortion procedures, we found 850 severe adverse events (1.6 per 1000 procedures, 95% confidence interval [CI] 1.5-1.7), and 5664 any adverse events (10.7 per 1000 procedures, 95% CI 10.4-11.0). Severe adverse events occurred in 194 out of 52 889 procedures in the low-volume group (3.7 per 1000 procedures, 95% CI 3.2-4.2) compared with 656 out of 476 252 procedures in the higher-volume group (1.4 per 1000 procedures, 95% CI 1.3-1.5), an adjusted odds ratio (OR) of 1.91 (95% CI 1.41-2.59). The odds of any adverse event were also higher in the low-volume versus higher-volume group (adjusted OR 1.19, 95% CI 1.02-1.40).Interpretation: Low physician procedure volumes are associated with an elevated risk of a complication after surgically induced abortion. Future investigation should compare processes of care between low- and higher-volume physicians to facilitate quality improvement in abortion care. [ABSTRACT FROM AUTHOR]

Background: Intentional injury, including suicide and assault, is a leading cause of maternal morbidity and mortality. We aimed to determine whether immigrant and nonimmigrant women differ in their 1-year risk of intentional injury after birth. Methods: This population-based retrospective cohort study used administrative data from Ontario from 2002 to 2012. Risk of self-inflicted injury (self-harm or suicide), and injury inflicted by others (assault or homicide), were each analyzed within 1 year after delivery of a live-born infant for immigrant and nonimmigrant mothers. Relative risks (RRs) were adjusted for maternal age, parity, income, resource utilization and psychiatric history. Results: The study included 327 279 immigrant and 942 502 nonimmigrant mothers. Risk of self-inflicted injury was similar among immigrants and nonimmigrants (adjusted RR 0.91, 95% confidence interval [CI] 0.78–1.04), with no variation by duration of residence or refugee status. Immigrants were at lower risk than nonimmigrants for injury inflicted by others (adjusted RR 0.57, 95% CI 0.51–0.64); that risk was higher among refugees than among nonrefugee immigrants (adjusted RR 1.79, 95% CI 1.33–2.41), and it was higher among long-term (adjusted RR 2.27, 95% CI 1.76–2.91) and medium-term (adjusted RR 1.58, 95% CI 1.19–2.11) immigrants than among recent immigrants. Variability by country of origin was observed for both injury types. Interpretation: Immigrant mothers have a reported risk for self-inflicted injury after birth similar to that of their Canadian-born counterparts. The extent to which selective underreporting of intentional injury in immigrant women might explain our findings is a key consideration for future research. [ABSTRACT FROM AUTHOR]

Background: The primary aim of this study was to examine weight gain during pregnancy and associated adverse outcomes across different types of antenatal health care providers. Our research question examined whether type of antenatal health care provider (family physician, obstetrician, midwife, or family physician plus obstetrician) was associated with differing rates of excess or inadequate weight gain and associated adverse outcomes including being large for gestational age, being small for gestational age, cesarean delivery and preterm birth. Methods: This retrospective cohort study used data from the Better Outcomes Registry & Network Information System, 2014–2016, for singleton hospital births at 20–42 weeks' gestation in Ontario. We calculated descriptive statistics to summarize patient characteristics and outcomes by antenatal health care provider. We calculated crude and adjusted relative risks with 95% confidence intervals (CIs) for the exposure (weight gain during pregnancy) relative to each secondary outcome by health care provider. We calculated population attributable fractions with 95% CIs to assess the proportion of secondary outcomes that could be prevented if inadequate or excess weight gain (according to the 2009 Institute of Medicine guidelines) were removed by health care provider. Results: The final cohort consisted of 231 697 pregnancies, of which 26 043 (11.2%), 136 994 (59.1%), 32 262 (13.9%) and 36 298 (15.7%) were managed by a family physician, obstetrician, midwife, and family physician plus obstetrician, respectively. Rates of weight gain below, within or above recommended levels were 31 742 (13.7%), 71 826 (31.0%) and 128 128 (55.3%), respectively, and did not differ across health care provider groups. No difference was observed in rates of secondary outcomes according to weight gain across health care providers. Excess weight gain was associated with a significant risk of being large for gestational age and cesarean delivery, and inadequate weight gain was associated with an increased risk of being small for gestational age and preterm birth. The population attributable fractions indicated a pronounced contribution of excess weight gain to being large for gestational age across all health care provider groups. Interpretation: Weight gain during pregnancy and rates of associated secondary outcomes did not differ according to antenatal health care provider. This suggests a need for further research exploring counselling techniques and strategies for all types of antenatal health care providers to use in order to promote optimal weight gain during pregnancy. [ABSTRACT FROM AUTHOR]

Background: A teenage woman's sexual health practices may be influenced by her mother's experience. We evaluated whether there is an intergenerational tendency for induced abortion between mothers and their teenage daughters.Methods: We conducted a retrospective population-based cohort study involving daughters born in Ontario between 1992 and 1999. We evaluated the daughters' data for induced abortions between age 12 years and their 20th birthday. We assessed each mother's history of induced abortion for the period from 4 years before her daughter's birth to 12 years after (i.e., when her daughter turned 12 years of age). We used Cox proportional hazard models to estimate a daughter's risk of having an induced abortion in relation to the mother's history of the same procedure. We adjusted hazard ratios (HRs) for maternal age and world region of origin, mental or physical health problems in the daughter, mother- daughter cohabitation, neighbourhood-level rate of teen induced abortion, rural or urban residence, and income quintile.Results: A total of 431 623 daughters were included in the analysis. The cumulative probability of teen induced abortion was 10.1% (95% confidence interval [CI] 9.8%-10.4%) among daughters whose mother had an induced abortion, and 4.2% (95% CI 4.1%-4.3%) among daughters whose mother had no induced abortion, for an adjusted HR of 1.94 (95% CI 1.86-2.01). The adjusted HR of a teenaged daughter having an induced abortion in relation to number of maternal induced abortions was 1.77 (95% CI 1.69-1.85) with 1 maternal abortion, 2.04 (95% CI 1.91-2.18) with 2 maternal abortions, 2.39 (95% CI 2.19-2.62) with 3 maternal abortions and 2.54 (95% CI 2.33-2.77) with 4 or more maternal abortions, relative to none.Interpretation: We found that the risk of teen induced abortion was higher among daughters whose mother had had an induced abortion. Future research should explore the mechanisms for intergenerational induced abortion. [ABSTRACT FROM AUTHOR]

Background: Cold-induced thermogenesis is known to improve insulin sensitivity, which may become increasingly relevant in the face of global warming. The aim of this study was to examine the relation between outdoor air temperature and the risk of gestational diabetes mellitus.Methods: We identified all births in the Greater Toronto Area from 2002 to 2014 using administrative health databases. Generalized estimating equations were used to examine the relation between the mean 30-day outdoor air temperature before the time of gestational diabetes mellitus screening and the likelihood of diagnosis of gestational diabetes mellitus based on a validated algorithm using hospital records and physician service claims.Results: Over the 12-year period, there were 555 911 births among 396 828 women. Prevalence of gestational diabetes mellitus was 4.6% among women exposed to extremely cold mean outdoor air temperatures (≤ -10°C) in the 30-day period before screening and increased to 7.7% among those exposed to hot mean 30-day temperatures (≥ 24°C). Each 10°C increase in mean 30-day temperature was associated with a 1.06 (95% confidence interval [CI] 1.04-1.07) times higher odds of gestational diabetes mellitus, after adjusting for maternal age, parity, neighbourhood income quintile, world region and year. A similar effect was seen for each 10°C rise in outdoor air temperature difference between 2 consecutive pregnancies for the same woman (adjusted odds ratio 1.06, 95% CI 1.03-1.08).Interpretation: In our setting, there was a direct relation between outdoor air temperature and the likelihood of gestational diabetes mellitus. Future climate patterns may substantially affect global variations in the prevalence of diabetes, which also has important implications for the prevention and treatment of gestational diabetes mellitus. [ABSTRACT FROM AUTHOR]

Background: We assessed variations in the male-female infant ratios among births to Canadian-born and Indian-born mothers according to year of birth, province and country of birth of each parent. Methods: In this population-based register study, we analyzed birth certificates of 5 853 970 singleton live births to Canadian-born and 177 990 singleton live births to Indian-born mothers giving birth in Canada from 1990 to 2011. Male-female ratios were stratified by live birth order and plotted by year of birth. Logistic regression was used to assess whether ratios varied between Canadian provinces and according to the birthplace of each parent. The deficit in the number of girls was estimated using bootstrap methods. Results: Among Canadian-born mothers, male-female ratios were about 1.05, with negligible fluctuations by birth order, year and province. Among Indian-born mothers, the overall male-female ratio at the third birth was 1.38 (95% confidence interval [CI] 1.34-1.41) and was 1.66 (95% CI 1.56-1.76) at the fourth or higher-order births. There was little variability in the ratios between provinces. Couples involving at least 1 Indian-born parent had higher than expected male-female ratios at the second and higher-order births, particularly when the father was Indian-born. The deficit in the expected number of girls among Indian immigrants to Canada in the study period was estimated to be 4472 (95% CI 3211-5921). Interpretation: Fewer than expected girls at the third and higher-order births have been born to Indian immigrants across Canada since 1990. This trend was also seen among couples of mixed nativity, including those involving a Canadian-born mother and an Indian-born father. Fathers should be considered when investigating sex ratios at birth. [ABSTRACT FROM AUTHOR]

Background: Skewed male:female ratios at birth have been observed among certain immigrant groups. Data on abortion practices that might help to explain these findings are lacking.Methods: We examined 1 220 933 births to women with up to 3 consecutive singleton live births between 1993 and 2012 in Ontario. Records of live births, and induced and spontaneous abortions were linked to Canadian immigration records. We determined associations of male:female infant ratios with maternal birthplace, sex of the previous living sibling(s) and prior spontaneous or induced abortions.Results: Male:female infant ratios did not appreciably depart from the normal range among Canadian-born women and most women born outside of Canada, irrespective of the sex of previous children or the characteristics of prior abortions. However, among infants of women who immigrated from India and had previously given birth to 2 girls, the overall male:female ratio was 1.96 (95% confidence interval [CI] 1.75-2.21) for the third live birth. The male:female infant ratio after 2 girls was 1.77 (95% CI 1.26-2.47) times higher if the current birth was preceded by 1 induced abortion, 2.38 (95% CI 1.44-3.94) times higher if preceded by 2 or more induced abortions and 3.88 (95% CI 2.02-7.50) times higher if the induced abortion was performed at 15 weeks or more gestation relative to no preceding abortion. Spontaneous abortions were not associated with male-biased sex ratios in subsequent births.Interpretation: High male:female ratios observed among infants born to women who immigrated from India are associated with induced abortions, especially in the second trimester of pregnancy. [ABSTRACT FROM AUTHOR]

Background: Concurrent admission of a mother and her newborn to separate intensive care units (herein referred to as co-ICU admission), possibly in different centres, can magnify family discord and stress. We examined the prevalence and predictors of mother-infant separation and mortality associated with co- ICU admissions. Methods: We completed a population-based study of all 1 023 978 singleton live births in Ontario between Apr. 1, 2002, and Mar. 31, 2010. We included data for maternal-infant pairs that had co-ICU admission (n = 1216), maternal ICU admission only (n = 897), neonatal ICU (NICU) admission only (n = 123 236) or no ICU admission (n = 898 629). The primary outcome measure was mother-infant separation because of interfacility transfer. Results: The prevalence of co-ICU admissions was 1.2 per 1000 live births and was higher than maternal ICU admissions (0.9 per 1000). Maternal- newborn separation due to interfacility transfer was 30.8 (95% confidence interval [CI] 26.9-35.3) times more common in the co-ICU group than in the no-ICU group and exceeded the prevalence in the maternal ICU group and NICU group. Short-term infant mortality (< 28 days after birth) was higher in the co-ICU group (18.1 per 1000 live births; maternal age- adjusted hazard ratio [HR] 27.8, 95% CI 18.2- 42.6) than in the NICU group (7.6 per 1000; ageadjusted HR 11.5, 95% CI 10.4-12.7), relative to 0.7 per 1000 in the no-ICU group. Short-term maternal mortality (< 42 days after delivery) was also higher in the co-ICU group (15.6 per 1000; age-adjusted HR 328.7, 95% CI 191.2-565.2) than in the maternal ICU group (6.7 per 1000; age-adjusted HR 140.0, 95% CI 59.5-329.2) or the NICU group (0.2 per 1000; age-adjusted HR 4.6, 95% CI 2.8-7.4). Interpretation: Mother-infant pairs in the co- ICU group had the highest prevalence of separation due to interfacility transfer and the highest mortality compared with those in the maternal ICU and NICU groups. [ABSTRACT FROM AUTHOR]

Background: There has been much discussion about whether female feticide occurs in certain immigrant groups in Canada. We examined data on live births in Ontario and compared sex ratios in different groups according to the mother's country or region of birth and parity. Methods: We completed a population-based study of 766 688 singleton live births between 2002 and 2007. We used birth records provided by Ontario Vital Statistics for live births in the province between 23 and 41 weeks' gestation. We categorized each newborn according to the mother's country or region of birth, namely Canada (n = 486 599), Europe (n = 58 505), South Korea (n = 3663), China (n = 23 818), Philippines (n = 15 367), rest of East Asia (n = 18 971), Pakistan (n = 18 018), India (n = 31 978), rest of South Asia (n = 20 695) and other countries (n = 89 074). We calculated male:female ratios and 95% confidence intervals (CIs) for all live births by these regions and stratified them by maternal parity at the time of delivery (0, 1, 2 or ≥ 3). Results: Among infants of nulliparous women, the male:female ratio was about 1.05 overall. As parity increased, the ratio remained unchanged among infants of Canadian-born women. In contrast, the male:female ratio was significantly higher among infants of primiparous women born in South Korea (1.20, 95% CI 1.09.1.34) and India (1.11, 95% CI 1.07.1.15) than among infants of Canadian-born primiparous women. Among multiparous women, those born in India were significantly more likely than Canadian-born women to have a male infant (parity 2, ratio 1.36, 95% CI 1.27. 1.46; parity ≥ 3, ratio 1.25, 95% CI 1.09.1.43). Interpretation: Our study of male:female ratios in Ontario showed that multiparous women born in India were significantly more likely than multiparous women born in Canada to have a male infant. [ABSTRACT FROM AUTHOR]

Background: The negative impact of diabetes mellitus is well recognized, yet little is known about the effect of this disease on the liver, an organ susceptible to nonalcoholic fatty liver disease related to insulin resistance. We evaluated whether adults with newly diagnosed diabetes were at increased risk of serious liver disease. Methods: We used administrative health databases for the province of Ontario (1994-2006) to perform a population-based matched retrospective cohort study. The exposed group comprised 438 069 adults with newly diagnosed diabetes. The unexposed comparison group -- those without known diabetes -- consisted of 2 059 708 individuals, matched 5:1 to exposed persons, by birth year, sex and local health region. We excluded individuals with preexisting liver or alcohol-related disease. The primary study outcome was the subsequent development of serious liver disease, namely, liver cirrhosis, liver failure and its sequelae, or receipt of a liver transplant. Results: The incidence rate of serious liver disease was 8.19 per 10 000 person-years among those with newly diagnosed diabetes and 4.17 per 10 000 person-years among those without diabetes. The unadjusted hazard ratio was 1.92 (95% confidence interval [CI] 1.83--2.01). After adjustment for age, income, urban residence, health care utilization and pre-existing hypertension, dyslipidemia, obesity and cardiovascular disease, the hazard ratio was 1.77 (95% CI 1.68--1.86). Interpretation: Adults with newly diagnosed diabetes appeared to be at higher risk of advanced liver disease, also known as diabetic hepatopathy. Whether this reflects nonalcoholic fatty liver disease or direct glycemic injury of the liver remains to be determined. [ABSTRACT FROM AUTHOR]

Background: The extent to which temporal increases in the use of prenatal ultrasonography reflect changes in maternal risk is unknown. In this population-based study, we examined the use of prenatal ultrasonography from 1996 to 2006 in Ontario. Methods: With fiscal year 1996/97 as the baseline, we evaluated the relative risk (RR) and 95% confidence interval (CI) for the change in rates of ultrasonography for each subsequent year. The RR was adjusted for maternal age, income, rural residence, maternal comorbidities, receipt of genetics consultation or amniocentesis - all in the index pregnancy - and history of complications in a prior pregnancy. Results: The study sample consisted of 1 399 389 singleton deliveries. The rate of prenatal ultrasonography increased from 2055 per 1000 pregnancies in 1996 to 3264 per 1000 in 2006 (adjusted RR 1.55, 95% CI 1.54-1.55). The rate increased among both women with low-risk pregnancies (adjusted RR 1.54, 95% CI 1.53-1.55) and those with highrisk pregnancies (adjusted RR 1.55, 95% CI 1.54-1.57). The proportion of pregnancies with at least four ultrasound examinations in the second or third trimesters rose from 6.4% in 1996 to 18.7% in 2006 (adjusted RR 2.68, 95% CI 2.61-2.74). Paradoxically, this increase was more pronounced among low-risk pregnancies (adjusted RR 2.92, 95% CI 2.83-3.01) than among high-risk pregnancies (adjusted RR 2.25, 95% CI 2.16-2.35). Interpretation: Substantial increases in the use of prenatal ultrasonography over the past decade do not appear to reflect changes in maternal risk. Nearly one in five women now undergo four or more ultrasound examinations during the second and third trimesters. Efforts to promote more appropriate use of prenatal ultrasonography for singleton pregnancies appear warranted. [ABSTRACT FROM AUTHOR]

Background: Elevated waist circumference and body mass index (BMI), both traditional measures of obesity, are accepted risk factors for type 2 diabetes mellitus. Girls who are obese experience earlier onset of puberty and possibly greater breast development. We sought to evaluate whether a woman's breast size in late adolescence is associated with an increased risk of type 2 diabetes mellitus in adulthood. Methods: In conjunction with the ongoing Nurses' Health Study II, which began to study risk factors for breast cancer among women in 1989, we conducted a prospective cohort study involving 92 106 of the participants. We assessed the risk of type 2 diabetes mellitus in relation to self-reported bra cup sizes, categorized as ≤ A, B, C and ≥ D cups, among participants at age 20. Results: The mean age of participants at baseline was 38.1 years. A total of 1844 new cases of type 2 diabetes mellitus arose at a mean age of 44.9 years during 886 443 personyears of follow-up. Relative to bra cup size ≤ A, the respective age-adjusted hazard ratios (and 95% confidence intervals [CIs]) were 2.30 (1.99-2.66) for B cup, 4.32 (3.71-5.04) for C cup and 4.99 (4.12-6.05) for ≥ D cup. Upon further adjustments for age at menarche, parity, physical activity, smoking status, diet, multivitamin use, family history of diabetes mellitus, BMI at age 18 and current BMI, the corresponding hazard ratios (and 95% CIs) were 1.37 (1.18-1.59) for B cup, 1.80 (1.53- 2.11) for C cup and 1.64 (1.34-2.01) for ≥ D cup. The addition of waist circumference to this model minimally changed the hazard ratios (and 95% CIs): 1.32 (1.14-1.53) for B cup, 1.71 (1.46-2.01) for C cup and 1.58 (1.29-1.94) for ≥ D cup. Interpretation: A large bra cup size at age 20 may be a predictor of type 2 diabetes mellitus in middle-aged women. Whether this relation is independent of traditional indicators of obesity remains to be determined. [ABSTRACT FROM AUTHOR]

Background: People who immigrate to Western nations may experience fewer chronic health problems than original residents of those countries, which raises concerns about long-term environmental or lifestyle factors in those countries. We tested whether the "healthy immigrant effect" extends to the risk of placental dysfunction during the short interval of pregnancy. Methods: We conducted a population-based retrospective cohort study of data for 796 105 women who had a first documented obstetric delivery in Ontario between 1995 and 2005. Recency of immigration was determined for each woman as the time from her enrolment in universal health insurance to her date of delivery, classified as less than 3 months, 3-5 months, 6-11 months, 12-23 months, 24-35 months, 36-47 months, 48-59 months and 5 years or more (the referent). The primary composite outcome was maternal placental syndrome (defined as a diagnosis of pre-eclampsia or eclampsia, placental abruption or placental infarction). Results: The mean age of the women was 28.8 years. Maternal placental syndrome occurred in 45 216 women (5.7%). The risk of this outcome was lowest among the women who had immigrated less than 3 months before delivery (3.8%) and highest among those living in Ontario at least 5 years (6.0%), for a crude odds ratio (OR) of 0.62 (95% confidence interval [CI] 0.54-0.71). After adjustment for maternal age, income status, pre-existing hypertension, diabetes mellitus, multiple gestation and receipt of prenatal ultrasonography, the risk of maternal placental syndrome was correlated with the number of months since immigration in a gradient manner (OR, 95% CI): less than 3 months (0.53, 0.47-0.61), 3-5 months (0.68, 0.61-0.76), 6-11 months (0.67, 0.63-0.71), 12-23 months (0.69, 0.66-0.73), 24-35 months (0.75, 0.70- 0.79), 36-47 months (0.75, 0.70-0.80) and 48-59 months (0.82, 0.77-0.87). Interpretation: There was a progressively lower risk of maternal placental syndromes associated with recency of immigration. The "healthy immigrant effect" may extend to common placental disorders, diminishes with the duration of residency and underscores the importance of nongenetic determinants of maternal health accrued over a brief period. [ABSTRACT FROM AUTHOR]

Presents a letter to the editor in response to the article "Vitamin B12, Homocysteine and Carotid Plaque in the Era of Folic Acid Fortification of Enriched Cereal Grain Products," by J. Robertson et al in a 2005 issue of "Canadian Medical Association Journal."

Background Women who are homeless during pregnancy may be exposed to poor nutrition, violence and substance use, yet the health status of their newborn infants has not been systematically evaluated. We undertook a study to provide preliminary estimates of the risk of adverse perinatal outcomes among Canadian women who are homeless or marginally housed during pregnancy, and the effect of concomitant substance use. Methods We conducted a retrospective cohort study at a single downtown hospital from October 2002 to December 2004, involving women who, during pregnancy, were homeless or underhoused (n = 80), substance users (n = 59) or neither (n = 3756). We noted neonatal measures such as birth weight and gestational age; the main study outcomes were preterm birth before 37 weeks' gestation, birth weight less than 2000 g and small for gestational age at birth. Results Homelessness or inadequate housing was associated with an odds ratio (adjusted for maternal age, gravidity and being a current smoker of tobacco) of 2.9 (95% confidence interval [CI] 1.4-6.1) for preterm delivery, 6.9 (95% CI 2.4-20.0) for infant birth weight under 2000 g and 3.3 (95% CI 1.1-10.3) for delivery of a newborn small for gestational age. Adjusted odds ratios for substance use during pregnancy were similar. In the combined presence of an underhoused or homeless state and maternal substance use, the adjusted risk estimates were 5.9 (95% CI 1.9-18.5), 16.6 (95% CI 3.5-79.3) and 5.6 (95% CI 1.1-28.7), respectively. Interpretation Homelessness and maternal substance use may reduce neonatal well-being through prematurity and low birth weight. [ABSTRACT FROM AUTHOR]

Assesses how hospital re-admission rates were affected by a clinical guideline aimed at discharging newborns from the hospital 24 hours after birth. Background; Method; Results; Interpretation.

Presents a letter to the editor about the diagnosis and treatment of vitamin B12 (cobalamin) deficiency.

Background: Maternal body mass and the presence of diabetes mellitus are probable risk factors for neural tube defects (NTDs). The association between maternal ethnicity and the risk of NTDs remains poorly understood, however. Methods: We performed a retrospective population-based study and included all women in Ontario who underwent antenatal maternal screening (MSS) at 15 to 20 weeks' gestation between 1994 and late 2000. Self-declared maternal date of birth, ethnicity and weight and the presence of pregestational diabetes mellitus were recorded in a standardized fashion on the MSS requisition sheet. NTDs were detected antenatally by ultrasonography or fetal autopsy and postnatally by considering all live and stillborn affected infants beyond 20 weeks' gestation. The risk of open NTD was evaluated across the 5 broad ethnic groups used for MSS, with white ethnicity as the referent. Results: Compared with white women ( n = 290 799), women of First Nations origin ( n = 1551) were at increased associated risk of an NTD-affected pregnancy (adjusted odds ratio [OR] 5.2, 95% confidence interval ([CI] 2.1-12.9). Women of other ethnic origins were not at increased associated risk compared with white women (women of Asian origin [ n = 75 590]: adjusted OR 0.9, 95% CI 0.6-1.3; black women [ n = 25 966]: adjusted OR 0.6, 95% CI 0.3-1.1; women of "other" ethnic origin [ n= 10 009]: adjusted OR 0.1, 95% CI 0.02-0.9). Interpretation: The associated risk of NTD-affected pregnancies was higher among women of First Nations origin than among women of other ethnic origins. The mechanisms for this discrepancy should be explored. [ABSTRACT FROM AUTHOR]

The author reflects on the study by Wen and colleagues on the use of folic acid antagonists which is associated to higher risk of placenta-mediated outcomes of pregnancy. He argues that the findings should not alter medical practice because of limited analysis of drug exposure and unreported congenital anomaly cases. He advices that even if trimethoprim-based antibiotics increase risk of placenta-mediated disease, it can be prescribed to pregnant women and those planning to get pregnant.

The authors express opinion on the use of a novel approach to investigate whether obstetric outcomes differ between woman attended by their regular-care obstetricians and those attended by an on-call obstetrician who did not provide antenatal care. The study showed a 13% increase in the rate of cesarean delivery among women attended by an on-call obstetrician. They note consistent care transitions and system redundancies as factors that may bridge potential care gaps.

January 2002, Health Canada issued an advisory, followed by a ban in August 2002, on the sale of herbal kava. One month after the advisory, 22 (67%) of 33 health food stores approached were selling kava. Two months after the ban, 17 (57%) of 30 stores continued to sell kava. These findings demonstrate that health food stores may need to be better informed about the sale of restricted natural health products. [ABSTRACT FROM AUTHOR]

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Background: Infants of immigrant women in Western nations generally have lower birth weights than infants of native-born women. Whether this difference is physiologic or pathological is unclear. We determined whether the use of birth-weight curves tailored to maternal world region of origin would discriminate adverse neonatal and obstetric outcomes more accurately than a single birth-weight curve based on infants of Canadian-born women. Methods: We performed a retrospective cohort study of in-hospital singleton live births (328 387 to immigrant women, 761 260 to nonimmigrant women) in Ontario between 2002 and 2012 using population health services data linked to the national immigration database. We classified infants as small for gestational age (< 10th percentile) or large for gestational age (≥ 90th percentile) using both Canadian and world region-specific birth-weight curves and compared associations with adverse neonatal and obstetric outcomes. Results: Compared with world region-specific birth-weight curves, the Canadian curve classified 20 431 (6.2%) additional newborns of immigrant women as small for gestational age, of whom 15 467 (75.7%) were of East or South Asian descent. The odds of neonatal death were lower among small-for-gestational-age infants of immigrant women than among those of nonimmigrant women based on the Canadian birth-weight curve (adjusted odds ratio [OR] 0.83, 95% confidence interval [CI] 0.72-0.95), but higher when small for gestational age was defined by the world region-specific curves (adjusted OR 1.24, 95% CI 1.08-1.42). Conversely, the odds of some adverse outcomes were lower among large-for-gestational-age infants of immigrant women than among those of nonimmigrant women based on world region-specific birth-weight curves, but were similar based on the Canadian curve. Interpretation: World region-specific birth-weight curves seemed to be more appropriate than a single Canadian population-based curve for assessing the risk of adverse neonatal and obstetric outcomes among small- and large-for-gestational-age infants born to immigrant women, especially those from the East and South Asian regions. [ABSTRACT FROM AUTHOR]

A letter to the editor is presented in response to the article "Pregnancy and the Risk of a Traffic Crash," by D. A. Redelmeier et al in a 2014 issue.

Background: The negative impact of diabetes mellitus is well recognized, yet little is known about the effect of this disease on the liver, an organ susceptible to nonalcoholic fatty liver disease related to insulin resistance. We evaluated whether adults with newly diagnosed diabetes were at increased risk of serious liver disease.Methods: We used administrative health databases for the province of Ontario (1994-2006) to perform a population-based matched retrospective cohort study. The exposed group comprised 438 069 adults with newly diagnosed diabetes. The unexposed comparison group--those without known diabetes--consisted of 2 059 708 individuals, matched 5:1 to exposed persons, by birth year, sex and local health region. We excluded individuals with pre-existing liver or alcohol-related disease. The primary study outcome was the subsequent development of serious liver disease, namely, liver cirrhosis, liver failure and its sequelae, or receipt of a liver transplant.Results: The incidence rate of serious liver disease was 8.19 per 10 000 person-years among those with newly diagnosed diabetes and 4.17 per 10 000 person-years among those without diabetes. The unadjusted hazard ratio was 1.92 (95% confidence interval [CI] 1.83-2.01). After adjustment for age, income, urban residence, health care utilization and pre-existing hypertension, dyslipidemia, obesity and cardiovascular disease, the hazard ratio was 1.77 (95% CI 1.68-1.86).Interpretation: Adults with newly diagnosed diabetes appeared to be at higher risk of advanced liver disease, also known as diabetic hepatopathy. Whether this reflects nonalcoholic fatty liver disease or direct glycemic injury of the liver remains to be determined. [ABSTRACT FROM AUTHOR]

Presents a response by Joel G. Ray to a letter to the editor about his group's study of ethnicity in relation to the development of neural tube effects by Joel Ray and associates, that was published in a previous issue of the "Canadian Medical Association Journal."