British Columbia Perinatal Data Registry Research Articles

Mining the Gap: Deriving Pregnancy Reference Intervals for Hematology Parameters Using Clinical Datasets.

Physiological changes during pregnancy invalidate use of general population reference intervals (RIs) for pregnant people. The complete blood count (CBC) is commonly ordered during pregnancy, but few studies have established pregnancy RIs suitable for contemporary Canadian mothers. Prospective RI studies are challenging to perform during pregnancy while retrospective techniques fall short as pregnancy and health status are not readily available in the laboratory information system (LIS). This study derived pregnancy RIs retrospectively using LIS data linked to provincial perinatal registry data. A 5-year healthy pregnancy cohort was defined from the British Columbia Perinatal Data Registry and linked to laboratory data from two laboratories. CBC and differential RIs were calculated using direct and indirect approaches. Impacts of maternal and pregnancy characteristics, such as age, body mass index, and ethnicity, on laboratory values were also assessed. The cohort contained 143 106 unique term singleton pregnancies, linked to >972 000 CBC results. RIs were calculated by trimester and gestational week. Result trends throughout gestation aligned with previous reports in the literature, although differences in exact RI limits were seen for many tests. Trimester-specific bins may not be appropriate for several CBC parameters that change rapidly within trimesters, including red blood cells (RBCs), some leukocyte parameters, and platelet counts. Combining information from comprehensive clinical databases with LIS data provides a robust and reliable means for deriving pregnancy RIs. The present analysis also illustrates limitations of using conventional trimester bins during pregnancy, supporting use of gestational age or empirically derived bins for defining CBC normal values during pregnancy.

Maternal and perinatal outcomes in primiparous singleton pregnancies conceived with assisted reproductive technology in British Columbia

ObjectiveTo evaluate the odds of developing adverse maternal and perinatal outcomes in primiparous singleton pregnancies conceived with assisted reproductive technology (ART) compared with pregnancies conceived without ART. Study designA retrospective population-based cohort study using data from the British Columbia Perinatal Data Registry. The population included primiparous women with singleton live or stillbirths delivering at or after 20 weeks’ gestation between April 1st 2008–March 31st, 2021. Women who conceived with ART were compared with those who conceived without ART. The main outcome measures were gestational diabetes, hypertensive disorders of pregnancy, preterm birth, low birth weight, neonatal intensive care unit admission, stillbirth, and 5-minute Apgar score. Adjusted odds ratios were calculated. ResultsThe study population included 191,059 primiparous women: 183,819 conceived without ART, 7,240 conceived using ART. After controlling for age, body mass index, pre-gestational diabetes, and smoking status, singleton pregnancies conceived by ART had significantly higher odds of gestational diabetes (OR 1.18, 95 % confidence interval [CI] 1.10–1.26) and hypertensive disorders of pregnancy (OR 1.39, 95 % CI 1.29–1.51). There were also significantly increased odds of preterm birth (OR 1.35, 95 % CI 1.25–1.46), low birth weight (OR 1.35, 95 % CI 1.23–1.49), and neonatal intensive care unit admission (OR 1.21, 95 % CI 1.11–1.32). There was not a statistically significant difference in the odds of stillbirth (OR 1.06, 95 % CI 0.72–1.57) or 5-minute Apgar score < 7 (OR 1.10, 95 % CI 0.97–1.26). ConclusionThere is an increased odds of developing several adverse maternal or neonatal outcomes in primiparous singleton pregnancies conceived by ART including gestational diabetes, hypertensive disorders of pregnancy, preterm birth, low birth weight, and increased incidence of neonatal intensive care unit admissions.

Child neurodevelopment following a diagnosis of isolated mild ventriculomegaly: a linked population-based study

Ventriculomegaly is a common prenatal diagnosis that has been linked with poor neurodevelopmental outcomes. Prior studies, however, have combined mild with severe cases, and included fetuses with other abnormalities. Also longer-term outcomes have been lacking. We examined if kindergarten-age child development scores following a diagnosis of isolated mild ventriculomegaly were lower than those of non-anomalous births in the general population. Singleton fetuses with an ultrasound at our tertiary center, 2004-2016, with lateral fetal ventricles diameter measuring 10.0 to 12.9 mm (unilateral or bilateral) and no other abnormal ultrasound findings were identified. Ultrasound data was linked with British Columbia (BC) population-based health data, including births in the BC Perinatal Data Registry and standardized kindergarten-age child development assessments (the Early Development Instrument [EDI]). The EDI assesses child development across five domains (emotional, social, language, communication, physical [each /10]), which sum to a Total EDI score /50. As schools only participate once per 3-year provincial testing wave, scores are available for 1/3 of births. Quantile regression was used to compare median EDI scores in children who had an antenatal diagnosis of isolated ventriculomegaly and those that did not, adjusting for sex and gestational age. We identified 65 non-anomalous pregnancies with mild ventriculomegaly, along with n= 358, 252 non-anomalous births in the BC population. EDI scores were available for approximately one-third of each group (n=23, n=124,621). Crude EDI scores were systematically lower with ventriculomegaly than the general population (e.g., Total EDI 39.3 vs 41.3, respectively; Figure 1). However, more ventriculomegaly cases were boys (67%), who also scored lower on EDI testing. After adjusting for sex, there were no differences in EDI scores (e.g., difference in Total EDI of -0.2 [95% CI: -4.2 to 3.9]; Figure 2). Isolated, mild ventriculomegaly was not associated with lower kindergarten-age child development test scores.View Large Image Figure ViewerDownload Hi-res image Download (PPT)

Cannabis use in pregnancy and maternal and infant outcomes: A Canadian cross-jurisdictional population-based cohort study.

With the recent legalization of cannabis in Canada, there is an urgent need to understand the effect of cannabis use in pregnancy. Our population-based study investigated the effects of prenatal cannabis use on maternal and newborn outcomes, and modification by infant sex. The cohort included 1,280,447 singleton births from the British Columbia Perinatal Data Registry, the Better Outcomes Registry & Network Ontario, and the Perinatal Program Newfoundland Labrador from April 1st, 2012 to March 31st, 2019. Logistic regression determined the associations between prenatal cannabis use and low birth weight, small-for-gestational age, large-for-gestational age, spontaneous and medically indicated preterm birth, very preterm birth, stillbirth, major congenital anomalies, caesarean section, gestational diabetes and gestational hypertension. Models were adjusted for other substance use, socio-demographic and-economic characteristics, co-morbidities. Interaction terms were included to investigate modification by infant sex. The prevalence of cannabis use in our cohort was approximately 2%. Prenatal cannabis use is associated with increased risks of spontaneous and medically indicated preterm birth (1.80[1.68-1.93] and 1.94[1.77-2.12], respectively), very preterm birth (1.73[1.48-2.02]), low birth weight (1.90[1.79-2.03]), small-for-gestational age (1.21[1.16-1.27]) and large-for-gestational age (1.06[1.01-1.12]), any major congenital anomaly (1.71[1.49-1.97]), caesarean section (1.13[1.09-1.17]), and gestational diabetes (1.32[1.23-1.42]). No association was found for stillbirth or gestational hypertension. Only small-for-gestational age (p = 0.03) and spontaneous preterm birth (p = 0.04) showed evidence of modification by infant sex. Prenatal cannabis use increases the likelihood of preterm birth, low birth weight, small-for-gestational age and major congenital anomalies with prenatally exposed female infants showing evidence of increased susceptibility. Additional measures are needed to inform the public and providers of the inherent risks of cannabis exposure in pregnancy.

Labor and delivery outcomes by delivery method in term deliveries in occiput posterior position: a population-based retrospective cohort study

Occiput posterior is the most common malposition in labor. Deliveries in occiput posterior position have been shown to have higher rates of adverse short-term maternal and neonatal outcomes compared with deliveries in occiput anterior position. There are no guidelines providing recommendations nor summarizing risks of adverse outcomes by delivery method to inform the decision-making process in occiput posterior delivery management. Population-based studies examining the outcomes associated with various management processes of occiput posterior position at the time of labor or delivery are lacking. This study aimed to describe the current management of term singleton occiput posterior deliveries in British Columbia, Canada and to examine the association between different management strategies and adverse outcomes by describing the rates of: occiput posterior malposition; and spontaneous vaginal delivery, operative vaginal delivery, and cesarean delivery from occiput posterior malposition. We also analyzed the rates of adverse labor and delivery outcomes stratified by fetal position and delivery mode, and the interaction effect of occiput posterior position and delivery mode on the rates of adverse outcomes. This was a retrospective cohort study of cephalic term singleton deliveries in British Columbia from 2004 to 2020, using the British Columbia Perinatal Data Registry. The obstetrical adverse outcome index (a composite of 10 adverse maternal or neonatal events), adverse outcome index subcomponent rates, and adverse outcome index-derived weighted scores were compared between deliveries stratified by fetal position at delivery (occiput posterior or occiput anterior) and occiput posterior deliveries stratified by delivery method. Multivariable log-binomial logistic regression was used to model the adverse outcome index score. Of 306,237 term births, 19% had occiput posterior position during labor, 37% of which persisted in occiput posterior position at delivery. Among occiput posterior deliveries, 27% were spontaneous vaginal deliveries, 8% vacuum, 5% forceps, 1% mixed vacuum-forceps, and 59% were cesarean delivery; this distribution differed from that of occiput anterior deliveries (P<.0001). Overall, adverse outcome index scores were significantly higher in persistent occiput posterior deliveries (8.8% had ≥1 adverse outcomes; adjusted rate ratio, 1.07 [1.01-1.14]) than in occiput posterior labors that rotated to occiput anterior deliveries; the most frequent adverse outcome was third- or fourth-degree lacerations. Neonatal adverse outcomes were also more frequent in occiput posterior delivery (4.3% vs 3.3%; adjusted rate ratio, 1.21 [1.10-1.35]), whereas maternal outcomes were similar between groups (4.8% vs 6.0%; adjusted rate ratio, 1.04 [0.96-1.13]). Among persistent occiput posterior deliveries, spontaneous vaginal delivery and cesarean delivery had the lowest proportion of deliveries with ≥1 adverse outcomes (6.1% and 6.2%), whereas forceps deliveries had the highest (38.1%); the largest contributor to the adverse outcomes were third- or fourth-degree lacerations. Among occiput posterior deliveries with any adverse outcome, cesarean delivery had the highest Severity Index score, due in part to the inclusion of third- or fourth-degree tears (which are assigned a comparatively low score) as the most common adverse event in the other vaginal delivery modes, and because of outcomes with a higher severity score being associated with cesarean delivery, such as uterine rupture (a reason for cesarean delivery) and intensive care unit admission (an outcome following cesarean delivery). Overall, in a multivariable regression model, delivery mode and the interaction between delivery mode and occiput posterior position were significant predictors of a delivery with ≥1 adverse outcomes, whereas occiput posterior position itself was not. One in five singleton deliveries at term gestation had occiput posterior position in labor; most of these rotated to occiput anterior by delivery, which had better outcomes than persistent occiput posterior deliveries. Among the latter, spontaneous vaginal delivery and cesarean delivery had the lowest frequency of adverse outcomes, whereas forceps deliveries had the highest. This study provides a robust updated analysis of birth outcomes following different occiput posterior management strategies, which can inform provider decision-making and counseling. Its observational design may limit its use for direct recommendations for management of occiput posterior malposition, yet the study helps to define the risks associated with different modes of delivery in the setting of occiput posterior malposition. With additional studies examining success rates of intermediate occiput posterior-occiput anterior rotation, other delivery management steps, and long-term outcomes, this study helps to define safe management of occiput posterior delivery.

DOES IN-VITRO FERTILIZATION AFFECT INTER-DELIVERY INTERVAL IN PATIENTS WITH RECURRENT PREGNANCY LOSS? A POPULATION STUDY

This study aimed to compare the interval to second live birth in women with recurrent pregnancy loss (RPL) who required IVF to those who conceived spontaneously. This retrospective study included women with live births in 2008-2018 from the British Columbia Perinatal Data Registry. This provincial registry collected perinatal variables from the mandatory reporting of all attended births. The cohort included RPL women with 2 recorded live births and were nulliparous at first delivery. The time interval was compared using a log-logistic survival model, controlling for factors such as age, BMI, city of residence, and number of miscarriages. There were 9503 women with RPL and 2 recorded deliveries; 4% of which required IVF to conceive the second child. IVF use was associated with older maternal age at first delivery (age 33.8 vs 28.9), previous IVF use (38.7% vs 1.5%), primary RPL (38.14% vs 28.73%), and higher number of miscarriages before the second delivery (2.64 vs 2.25) compared to those who conceived spontaneously (P all < 0.0001). In the unadjusted analysis, the duration from first delivery to second birth was significantly longer in those who required IVF compared to the control group, 4.1 and 3.8 years respectively (P = 0.0002). After adjustment, those who required IVF had a longer interval to second birth among younger women, but this difference was attenuated among older women. There was no significant difference in the time to second delivery after IVF use compared to spontaneous conception in RPL patients ≥ 35 years old at first birth. However, the study showed that younger women who conceived the second child with IVF had a longer inter-delivery interval. This may be related to underlying differences in infertility diagnosis and/or family planning.

Maternal vitamin B12 status in early pregnancy and its association with birth outcomes in Canadian mother-newborn Dyads.

Vitamin B12 (B12) is a co-enzyme essential for fetal growth and development. Lower maternal B12 status has been associated with preterm birth (<37 gestational weeks) and low birth weight (<2500 g), which are linked to morbidity and mortality across the lifespan. In Canada, 17-25 % of women in early pregnancy had a serum total B12 concentration <148 pmol/l and maternal total B12 concentration decreased throughout pregnancy. This study aimed to determine the association between maternal B12 status and birth outcomes in Canadian mother-newborn dyads. A secondary analysis of 709 mother-newborn dyads in British Columbia (BC), Canada, was conducted. Bio-banked first- (n 656) and second-trimester (n 709) maternal serum samples of apparently healthy South Asian (50 %) and European (50 %) women from the BC Prenatal Genetic Screening Program were quantified for B12 biomarkers (total B12, holotranscobalamin (holoTC), methylmalonic acid (MMA) and total homocysteine (tHcy)). Obstetric history and birth outcome data were obtained from the BC Perinatal Data Registry. All associations were determined using multiple linear regression. Maternal serum total B12, holoTC, MMA and tHcy had a mean weekly decrease of 3·64 pmol/l, 1·04 pmol/l, 1·44 nmol/l and 0·104 μmol/l, respectively (P < 0·001). Despite a total B12 concentration <148 pmol/l among 20-25 % of the women, maternal B12 biomarker concentrations were not associated with birth weight z-score, head circumference z-score and gestational age at birth (P > 0·05). Additional research in women at high risk of adverse birth outcomes and the association between maternal B12 status and functional, for example, cognitive, outcomes is needed.

Maternal alcohol use, adverse neonatal outcomes and pregnancy complications in British Columbia, Canada: a population-based study

BackgroundThe current study aimed to estimate the prevalence of alcohol use identified as a risk factor during pregnancies by the antenatal care providers, resulting in live births in British Columbia (BC) and to examine associations between alcohol use, adverse neonatal outcomes, and pregnancy complications.MethodsThis population-based cross-sectional study utilized linked obstetrical and neonatal records within the BC Perinatal Data Registry (BCPDR), for deliveries that were discharged between January 1, 2015 and March 31, 2018. The main outcome measures were alcohol use identified as a risk factor during pregnancy, associated maternal characteristics, pregnancy complications, and adverse neonatal outcomes. Estimates for the period and fiscal year prevalence were calculated. Chi-square tests were used to compare adverse neonatal outcomes and pregnancy complications by alcohol use during pregnancy identified as a risk factor. Logistic regression was used to examine the association between alcohol use identified as a risk factor during pregnancy and adverse neonatal outcomes and pregnancy complications, after adjusting for identified risk factors.ResultsA total of 144,779 linked records within the BCPDR were examined. The period prevalence of alcohol use during pregnancy identified as a risk factor was estimated to be 1.1% and yearly prevalence was 1.1, 1.1, 1.3 and 0.9% from the 2014/2015 to 2017/2018 fiscal years, respectively.Alcohol use identified as a risk factor was associated with younger maternal age, fewer antenatal visits, being primiparous, a history of mental illness, substance use and smoking.Neonates with alcohol use during pregnancy identified as a risk factor had greater odds of being diagnosed with: “low birth weight (1000-2499g)” (ICD-10: P07.1; aOR = 1.25; 95% CI: 1.01, 1.53), “other respiration distress of newborn” (ICD-10: P22.8; aOR = 2.57; 95% CI: 1.52, 4.07), “neonatal difficulty in breastfeeding” (ICD-10: P92.5; aOR = 1.97; 95% CI: 1.27, 2.92) and “feeding problems, unspecified” (ICD-10: P92.9; aOR = 2.06; 95% CI: 1.31, 3.09).ConclusionsThe prevalence of alcohol use during pregnancy identified as a risk factor was comparable to previous estimates within the BCPDR. Identified prenatal alcohol exposure was associated with notable differences in maternal and neonatal characteristics and adverse neonatal outcomes. More consistent, thorough screening and prevention efforts targeting alcohol use in pregnancy are urgently needed in Canada.

The Development of a Prediction Model for Vaginal Birth After Cesarean Section (VBAC) [34P

INTRODUCTION: Pregnant women who have had a previous cesarean section face the decision to either undergo a repeat elective cesarean or to attempt vaginal birth after cesarean (VBAC). The goal of this project was to determine the factors that predict success of VBAC in women with one prior cesarean section in the population of British Columbia, Canada. METHODS: Data were drawn from the British Columbia Perinatal Data Registry. We performed a retrospective analysis of 8291 cephalic term singleton planned vaginal births in British Columbia to women with a previous cesarean. Using block multivariate logistic regression, we analyzed the variables, both modifiable and non-modifiable, most predictive of successful VBAC. A result was considered statistically significant if its p value was &lt;.05. RESULTS: Of the 8291 planned VBAC births, 5960 were successful, while 2331 resulted in cesarean deliveries. Predictive variables were: maternal age, height and BMI, whether or not she had a vaginal birth within 2 years of the planned VBAC, whether she had a recurrent indication for the prior cesarean, whether she was administered oxytocin or prostaglandins for labor augmentation or induction, whether she was given an epidural, and the size of hospital in which she gave birth. CONCLUSION: A prediction model, incorporating eight variables has been developed. This model can inform shared decision-making and guide individualized counselling for eligible women on the chance of VBAC success. We hope that this prediction model will contribute to the literature and ultimately lower the probability of complications and adverse outcomes in childbirth.

Improving birth outcomes for women who are substance using or have mental illness: a Canadian cohort study comparing antenatal midwifery and physician models of care for women of low socioeconomic position

BackgroundSome observational studies have shown improved birth outcomes for women of low socioeconomic position (SEP) receiving antenatal midwifery versus physician care. To understand for whom and under what circumstances midwifery care is associated with better birth outcomes we examined whether psychosocial risk including substance use, mental illness, social assistance, residence in a neighbourhood of low/moderate SEP, and teen maternal age modified the association between model of care (midwifery versus physician) and small-for-gestational-age (SGA) or preterm birth (PTB) for women of low SEP.MethodsFor this retrospective cohort study, maternity data from the British Columbia Perinatal Data Registry were linked with Medical Services Plan billing data. We report adjusted odds ratios (aORs) and 95% confidence intervals (CIs) for SGA birth (< the 10th percentile) and PTB (< 37 weeks’ completed gestation). For tests of interaction between antenatal models of care and psychosocial risk, p-values < 0.10 were considered statistically significant. Women were eligible for inclusion if they were residents of British Columbia, Canada, carried a singleton fetus, had low to moderate medical/obstetric risk, birthed between April 1, 2008 and Dec. 31, 2012, and received a health insurance subsidy (n = 33,937).ResultsMidwifery versus obstetrician patients had lower odds of PTB. The difference was 31% larger among substance users (aOR 0.24, 95% CI: 0.11–0.54) compared to non-substance users (aOR 0.55, 95% CI: 0.45–0.68). Additionally, there was a 34% statistically significant absolute difference in odds of PTB for midwifery versus obstetrician patients with both mental illness and substance use (aOR 0.18, 95% CI: 0.06–0.55) compared to women with neither mental illness nor substance use (aOR 0.52, 95% CI: 0.41–.66). Results demonstrated a consistent association between midwifery versus physician care and lower odds of SGA, yet effects were not statistically significantly different for women with higher or lower psychosocial risk.ConclusionAmong low SEP women in British Columbia, Canada, antenatal midwifery compared to obstetrician care was associated with reduced odds of PTB. Odds were lower among women with substance use, and mental illness and substance use, than among women without these risk factors.

Unknown Antenatal HIV-Infection Status Has Declined Over Time in British Columbia, Canada

ObjectivesThe objective was to determine whether the proportion of pregnant women with unknown antenatal HIV-infection status is declining over time in British Columbia (BC) and whether associated factors are amenable to intervention. MethodsThrough a retrospective cohort study of all deliveries in the British Columbia Perinatal Data Registry from 2005 to 2011, we examined the association between year of delivery and no recorded antenatal HIV test result. The trend in unknown antenatal HIV-infection status over time was evaluated by the Cochran-Mantel-Haenzsel test and multivariable logistic regression was used to determine the odds of unknown antenatal HIV-infection status by year of delivery. ResultsA total of 299 771 deliveries were included; 9.1% had unknown antenatal HIV-infection status with a declining trend from 12.7% to 5.5% from 2005 to 2011 (P< 0.0001). Adjusted for maternal age, parity, gestation, and number of antenatal visits, pregnant women were 64% less likely to not have antenatal HIV testing in 2011 compared to 2005 (adjusted odds ratio [aOR] 0.36; 95% CI 0.34–0.38). The odds of no antenatal HIV testing were 54% higher in multiparous compared to primiparous women (aOR 1.54; 95% CI 1.49–1.58), and each additional antenatal visit reduced the odds of no antenatal HIV testing by 8% (aOR 0.92; 95% CI 0.92–0.93). ConclusionThe declining trend in unknown antenatal HIV-infection status in BC is encouraging. Consistent with Canadian and BC HIV testing guidelines, further strengthening of routine testing at the first antenatal visit in all pregnancies irrespective of previous HIV testing, particularly in multiparous women, could achieve universal pregnancy HIV testing in BC.

Safety of labour and delivery following closures of obstetric services in small community hospitals.

In recent decades, many smaller hospitals in British Columbia, Canada, have stopped providing planned obstetric services. We examined the effect of these service closures on the labour and delivery outcomes of pregnant women living in affected communities. We used maternal postal codes to identify delivery records (1998-2014) of women residing in a community affected by service closure. The records were obtained from the British Columbia Perinatal Data Registry. We examined the effect of the closures using a within-communities fixed-effects framework and included similar-sized communities without service closures to control for underlying time trends. The primary outcome was a previously published composite measure of labour and delivery safety, the Adverse Outcome Index, which includes adverse events such as birth injury and unanticipated operative procedures, and includes weights for severity of adverse events. Secondary outcomes included maternal or newborn transfer, and use of obstetric interventions. We found little evidence that closure of planned obstetric services affected the risk of composite adverse maternal-newborn outcome (-0.4 excess adverse events per 100 deliveries, 95% confidence interval [CI] -2.0 to 1.1), or most other secondary outcomes. The severity of composite outcome events decreased following the closures (rate ratio 0.58, 95% CI 0.36 to 0.89). Closures were associated with increases in use of epidural analgesia (3.4 excess events per 100 deliveries, 95% CI 0.4 to 6.3) and length of antepartum stay (0.6 h, 95% CI 0.1 to 1.0 h). Closure of planned obstetric services in low-volume hospitals was not associated with an increase or decrease in frequency of adverse events during labour and delivery.

Sex Ratios Among Births in British Columbia, 2000-2013.

Previous studies have reported distorted sex ratios among live births within specific immigrant groups in Canada. We carried out an investigation into sex ratios in British Columbia. All stillbirths and live births to residents of British Columbia from April 2000 to March 2013 were included in the study, with data obtained from the British Columbia Perinatal Data Registry. We examined sex ratios among births and among pregnancy terminations that resulted in a stillbirth or live birth. Analyses were stratified by congenital anomaly status, maternal residence, and parity. The study population included 567 225 stillbirths and live births. In the Fraser Health Authority, the sex ratio among births without congenital anomalies was 51.3% males (95% CI 51.1 to 51.5); this was significantly higher than the sex ratio of 40.7% males (95% CI 33.2 to 48.6) among late pregnancy terminations without congenital anomalies (P= 0.008). However, in British Columbia, excluding the Fraser Health Authority, the same sex ratios were 51.1% (95% CI 50.9 to 51.3) and 51.1% (95% CI 45.5 to 56.7), respectively (P= 0.99). Sex ratios among births to multiparous women were also significantly different in the Fraser Health Authority. Only a negligible fraction of the shortfall in female births in the Fraser Health Authority could be explained by sex ratio distortions among late pregnancy terminations. Sex ratios among stillbirths and live births to residents of the Fraser Health Authority are distorted relative to those observed elsewhere in British Columbia. This is likely due to sex differences in early pregnancy terminations.

Feasibility of Implementing a Standardized Clinical Performance Indicator to Evaluate the Quality of Obstetrical Care in British Columbia.

To establish the feasibility of implementing a previously-published clinical standardized performance indicator, the Adverse Outcome Index (AOI), using routinely-collected data in a population-based perinatal database and to examine variation in the indicator over time and between hospitals. Maternal and newborn medical record data contained in the British Columbia Perinatal Data Registry, 2004-2013, were used to calculate an AOI (a composite of 10 maternal and newborn adverse events) and its severity-weighted scores, the Weighted Adverse Outcome Score and the Severity Index. Temporal trends in the indices were examined by plotting annual risks and weighted risks with 95% confidence intervals. Hospital-level risks were calculated with 95% confidence intervals, adjusting for patient case-mix. Among 410,054 singleton deliveries in British Columbia, the risk of AOI was 5.8 per 100, while the Weighted Adverse Outcome Score and Severity Index were 1.6 and 27.4, respectively. The risk of AOI did not change significantly over the study period, while the Severity Index decreased from 29.3 (95% CI 26.7-31.9) in 2004 to 23.9 (22.0-25.8) in 2013. Fifteen of 52 hospitals had risks of AOI significantly above the provincial median. The hospitals' risks of AOI were not correlated with their Severity Indices (r = 0.02). The AOI can successfully be estimated using data from a population-based database, and used to monitor trends in safety of labour and delivery over time and between hospitals. The low correlation between frequency and severity of adverse events confirms the importance of considering event severity in perinatal population health surveillance.

Validating the British Columbia Perinatal Data Registry: a chart re-abstraction study.

BackgroundThe British Columbia Perinatal Data Registry (BCPDR) contains individual-level obstetrical and neonatal medical chart data for virtually all births occurring in British Columbia, Canada. The objective of this study was to assess the validity of information in the BCPDR by performing a provincial chart re-abstraction study.MethodsA two-stage stratified clustered sampling design was employed. Obstetrical facilities were stratified based on geographic location and obstetrical volume. Charts of mothers and newborns with a length of stay of five or more days or transfer to another facility following the delivery were oversampled. A total of 85 maternal and 32 newborn variables were assessed for completeness (percent completion) and validity (sensitivity and specificity for categorical variables, intra-class correlation coefficient [ICC] for continuous variables).Results1,084 maternal and 1,142 newborn charts were abstracted. Mandatory variables such as primary indication for induction and primary indication for cesarean delivery were 100 % complete. Some variables such as pre-pregnancy weight were relatively more complete in the re-abstraction as compared with the BCPDR (83.0 % vs 76.8 %; p < 0.001). The validity of key surveillance variables was high (e.g., HIV screening completed [sensitivity 98.0 %, 95 % confidence interval (CI) 97.0–98.8 %; specificity 72.3 %, 95 % CI 60.8–81.9 %], induction of labour [sensitivity 93.9 %, 95 % CI 90.2–96.5 %; specificity 98.7 %, 95 % CI 97.7–99.3 %], primary elective cesarean delivery [sensitivity 96.0 %, 95 % CI 83.8–99.7 %; specificity 99.8 %, 95 % CI 99.4–100.0 %], gestational age from newborn examination [ICC 0.99, 95 % CI 0.99–0.99]). Examples of variables with lower validity included total admissions prior to delivery episode, maternal smoking status, and timing of breastfeeding initiation.ConclusionMany important clinical and population health variables in the BCPDR had excellent validity. Some key variables warrant strengthening through improved definitions, system changes, and abstractor training.Electronic supplementary materialThe online version of this article (doi:10.1186/s12884-015-0563-7) contains supplementary material, which is available to authorized users.

Maternal and newborn outcomes after a prior cesarean birth by planned mode of delivery and history of prior vaginal birth in British Columbia: a retrospective cohort study.

As rates for cesarean births continue to rise, more women are faced with the choice to plan a vaginal or a repeat cesarean birth after a previous cesarean. The objective of this population-based retrospective cohort study was to compare the safety of planned vaginal birth with cesarean birth after 1-2 previous cesarean sections. We identified singleton term births in British Columbia from 2000 to 2008 using data from the British Columbia Perinatal Data Registry. Women carrying a singleton fetus in cephalic presentation at term (37-41 weeks of gestation completed) with 1-2 prior cesarean births were included. Those with gestational hypertension, pre-existing diabetes and cardiac disease were excluded. Maternal and neonatal outcomes were classified as either life-threatening or non-life threatening. We compared outcomes among women with none versus at least 1 previous vaginal birth, by planned method of delivery. We estimated relative risks (RR) and 95% confidence intervals (CI) for composite outcomes using Poisson regression. Of the 33 812 women in the sample, 5406 had a history of vaginal delivery and 28 406 did not. The composite risk for life-threatening maternal outcomes was elevated among women planning vaginal compared with cesarean birth both with and without a prior vaginal birth (RR 2.06, 95% CI 1.20-3.52) and (2.52, 95% CI 2.04-3.11). Absolute differences (attributable risk [AR]) were 1.01% and 1.31% respectively. Non-life threatening maternal outcomes were decreased among women planning a vaginal birth if they had had at least 1 prior vaginal delivery (RR 0.51, 95% CI 0.33-0.77; AR 1.17%). The composite risk of intrapartum stillbirth, neonatal death or life-threatening neonatal outcomes did not differ among women planning vaginal or cesarean birth with a prior vaginal delivery and non-life threatening neonatal outcomes were decreased, (RR 0.67, 95% CI 0.52-0.86); AR 1.92%). After 1 or 2 previous cesarean births, risks for adverse outcomes between planned vaginal and cesarean birth are reduced among women with a prior vaginal birth. Our data offer women and their health care providers the opportunity to consider risk profiles separately for women who have and have not had a prior vaginal delivery.

Predicting the Spontaneous Onset of Labour in Post-Date Pregnancies: A Population-Based Retrospective Cohort Study

ObjectiveTo estimate the probability of spontaneous onset of labour (SOL) among women with uncomplicated pregnancies who have reached 41+0 weeks and to examine the influence of maternal characteristics on this event. MethodsWe conducted a population-based retrospective cohort study of women with uncomplicated singleton pregnancies in cephalic presentation between 41+0 and 42+0 weeks’ gestation. Detailed clinical information was obtained from the British Columbia Perinatal Data Registry. We determined the time from 41+0 weeks to the exact day and time of SOL, pre-labour Caesarean section, or onset of labour following induction. A Kaplan-Meier curve was created to estimate the probability of SOL. A Cox regression model was used to assess the independent influence of maternal age, parity, BMI, and pregnancy weight gain on the SOL, and to assess the extent to which prediction of SOL could be individualized according to a woman’s characteristics. ResultsAmong 15 253 women undelivered at 41+0 weeks, there was a 67.6% (95% CI 66.4% to 68.7%) chance of SOL by 41+6 weeks. Although SOL was statistically more likely in younger women, higher parity, lower BMI, and lower weight gain (P<0.01), the multivariable model's predictive ability was poor (c-statistic 0.56). ConclusionMaternal characteristics were not a strong determinant for successful individualized prediction of SOL in women with uncomplicated pregnancies reaching 41+0 weeks of gestation. Our population-based estimates of the daily occurrence of SOL can be used to inform discussions with women on when to offer induction of labour.

Epidemiological investigation of a temporal increase in atonic postpartum haemorrhage: a population-based retrospective cohort study.

ObjectiveIncreases in atonic postpartum haemorrhage (PPH) have been reported from several countries in recent years. We attempted to determine the potential cause of the increase in atonic and severe atonic PPH.DesignPopulation-based retrospective cohort study.SettingBritish Columbia, Canada, 2001–2009.PopulationAll women with live births or stillbirths.MethodsDetailed clinical information was obtained for 371 193 women from the British Columbia Perinatal Data Registry. Outcomes of interest were atonic PPH and severe atonic PPH (atonic PPH with blood transfusion ≥1 unit; atonic PPH with blood transfusion ≥3 units or procedures to control bleeding), whereas determinants studied included maternal characteristics (e.g. age, parity, and body mass index) and obstetrics practice factors (e.g. labour induction, augmentation, and caesarean delivery). Year-specific unadjusted and adjusted odds ratios for the outcomes were compared using logistic regression.Main outcome measuresAtonic PPH and severe atonic PPH.ResultsAtonic PPH increased from 4.8% in 2001 to 6.3% in 2009, atonic PPH with blood transfusion ≥1 unit increased from 16.6 in 2001 to 25.5 per 10 000 deliveries in 2009, and atonic PPH with blood transfusion ≥3 units or procedures to control bleeding increased from 11.9 to 17.6 per 10 000 deliveries. The crude 34% (95% CI 26–42%) increase in atonic PPH between 2001 and 2009 remained unchanged (42% increase, 95% CI 34–51%) after adjustment for determinants of PPH. Similarly, adjustment did not explain the increase in severe atonic PPH.ConclusionsChanges in maternal characteristics and obstetric practice do not explain the recent increase in atonic and severe atonic PPH.

Trends in postpartum hemorrhage from 2000 to 2009: a population-based study

BackgroundPostpartum hemorrhage, a major cause of maternal death and severe maternal morbidity, increased in frequency in Canada between 1991 and 2004. We carried out a study to describe the epidemiology of postpartum hemorrhage in British Columbia, Canada, between 2000 and 2009.MethodsThe study population included all women residents of British Columbia who delivered between 2000 and 2009. Data on postpartum hemorrhage by subtypes and severity were obtained from the British Columbia Perinatal Data Registry. Among women with postpartum hemorrhage, severe cases were identified by the use of blood transfusions or procedures to control bleeding. Rates of postpartum hemorrhage and changes over time were assessed using rates, rate ratios and 95% confidence intervals (CI).ResultsThe rate of postpartum hemorrhage increased by 27% (95% CI 21-34%) between 2000 and 2009 (from 6.3% to 8.0%), while atonic postpartum hemorrhage rates increased by 33% (95% CI 26-41%) from 4.8% to 6.4%. Atonic postpartum hemorrhage with blood transfusion increased from 17.8 to 25.5 per 10,000 deliveries from 2000 to 2009 and atonic postpartum hemorrhage with either suturing of the uterus, ligation of pelvic vessels or embolization increased from 1.8 to 5.6 per 10,000 deliveries from 2001 to 2009. The increase in atonic postpartum hemorrhage was most evident between 2006 and 2009 and occurred across regions, hospitals and various maternal, fetal and obstetric characteristics.ConclusionsAtonic postpartum hemorrhage and severe atonic postpartum hemorrhage increased in British Columbia between 2000 and 2009. Further research is required to identify the cause of the increase.