Sharon Bartholomew

Incidence, risk factors, and associated complications of eclampsia.

OBJECTIVE: To estimate trends in incidence and identify risk factors and maternal and neonatal consequences of eclampsia in Canada. METHODS: We conducted a population-based cohort study of all women and their newborns (N=1,910,729) delivered in the hospital in Canada (excluding Quebec) from 2003 to 2009. The data were obtained from the Canadian Institute for Health Information. Logistic models were used to examine the association with potential determinants and consequences of eclampsia. RESULTS: The incidence of eclampsia declined dramatically from 12.4 per 10,000 deliveries in 2003 to 5.9 in 2009. Among singleton deliveries, nulliparity (adjusted odds ratio [OR] 2.3; 95% confidence interval [CI] 2.0–2.6), anemia (adjusted OR 2.4; 95% CI 2.0–3.0), and existing heart disease (adjusted OR 4.8; 95% CI 2.9–7.3) increased the risk of eclampsia. The declining trend in eclampsia remained unchanged after accounting for changes in potential determinants and risk factors during the study period. Eclampsia was associated with increased risks of maternal death (adjusted OR 26.8; 95% CI 9.7–73.8), assisted ventilation (adjusted OR 102.3; 95% CI 78.2–133.8), respiratory distress syndrome (adjusted OR 36.2; 95% CI 15.3–85.3), acute renal failure (adjusted OR 20.9; 95% CI 11.4–38.3), obstetric embolism (adjusted OR 9.1; 95% CI 4.1–19.9), and other complications. Adverse neonatal outcomes associated with eclampsia included neonatal death (adjusted OR 2.9; 95% CI 1.6–5.5), respiratory distress syndrome (adjusted OR 5.1; 95% CI 4.1–6.3), and small-for-gestational age birth (adjusted OR 2.6; 95% CI 2.3–3.0). CONCLUSION: Despite declining incidence and improved care of women with eclampsia, the condition remains strongly associated with serious adverse consequences. LEVEL OF EVIDENCE: II

Amniotic fluid embolism: incidence, risk factors, and impact on perinatal outcome.

Please cite this paper as: Kramer M, Rouleau J, Liu S, Bartholomew S, Joseph K for the Maternal Health Study Group of the Canadian Perinatal Surveillance System. Amniotic fluid embolism: incidence, risk factors, and impact on perinatal outcome. BJOG 2012;119:874–879.

Temporal Trends in Postpartum Hemorrhage and Severe Postpartum Hemorrhage in Canada From 2003 to 2010

OBJECTIVE Increases in postpartum hemorrhage have been reported from several countries. We assessed temporal trends in postpartum hemorrhage and severe postpartum hemorrhage in Canada between 2003 and 2010. METHODS We carried out a population-based cohort study of all hospital deliveries in Canada (excluding Quebec) from 2003 to 2010 (n = 2 193 425), using data from the Canadian Institute for Health Information. Postpartum hemorrhage was defined as a blood loss of ≥ 500 mL following vaginal delivery or ≥ 1000 mL following Caesarean section, or as noted by the care provider. Severe postpartum hemorrhage was defined as postpartum hemorrhage plus blood transfusion, hysterectomy, or other procedures to control bleeding (including uterine suturing or ligation/embolization of pelvic arteries). Temporal trends were assessed using the chi-square test for trend, relative risks, and logistic regression. RESULTS Postpartum hemorrhage increased by 22% (95% CI 20% to 25%) from 5.1% in 2003 to 6.2% in 2010 (P < 0.001), driven by a 29% increase (95% CI 26% to 33%) in atonic postpartum hemorrhage (3.9% in 2003 vs. 5.0% in 2010, P < 0.001). Postpartum hemorrhage with blood transfusion increased from 36.7 to 50.4 per 10 000 deliveries (P < 0.001), while postpartum hemorrhage with hysterectomy increased from 4.9 to 5.8 per 10 000 deliveries (P < 0.01). Postpartum hemorrhage with uterine suturing, or ligation/embolization of pelvic arteries, increased from 4.1 to 10.7 per 10 000 deliveries (P < 0.001). These increases occurred in most provinces and territories, and could not be explained by changes in maternal, fetal, and obstetric factors. CONCLUSION Rates of postpartum hemorrhage and severe postpartum hemorrhage continued to increase in Canada between 2003 and 2010.

Hypertensive disorders of pregnancy and the recent increase in obstetric acute renal failure in Canada: population based retrospective cohort study

Objective To examine whether changes in postpartum haemorrhage, hypertensive disorders of pregnancy, or other risk factors explain the increase in obstetric acute renal failure in Canada. Design Retrospective cohort study. Setting Canada (excluding the province of Quebec). Participants All hospital deliveries from 2003 to 2010 (n=2 193 425). Main outcome measures Obstetric acute renal failure identified by ICD-10 diagnostic codes. Methods Information on all hospital deliveries in Canada (excluding Quebec) between 2003 and 2010 (n=2 193 425) was obtained from the Canadian Institute for Health Information. Temporal trends in obstetric acute renal failure were assessed among women with and without postpartum haemorrhage, hypertensive disorders of pregnancy, or other risk factors. Logistic regression was used to determine if changes in risk factors explained the temporal increase in obstetric acute renal failure. Results Rates of obstetric acute renal failure rose from 1.66 to 2.68 per 10 000 deliveries between 2003-04 and 2009-10 (61% increase, 95% confidence interval 24% to 110%). Adjustment for postpartum haemorrhage, hypertensive disorders, and other factors did not attenuate the increase. The temporal increase in acute renal failure was restricted to deliveries with hypertensive disorders (adjusted increase 95%, 95% confidence interval 38% to 176%), and was especially pronounced among women with gestational hypertension with significant proteinuria (adjusted increase 171%, 71% to 329%). No significant increase occurred among women without hypertensive disorders (adjusted increase 12%, −28 to 72%). Conclusions The increase in obstetric acute renal failure in Canada between 2003 and 2010 was restricted to women with hypertensive disorders and was especially pronounced among women with pre-eclampsia. Further study is required to determine the cause of the increase among women with pre-eclampsia.

Temporal trends and regional variations in severe maternal morbidity in Canada, 2003 to 2007.

OBJECTIVE To identify temporal trends and regional variations in severe maternal morbidity in Canada using routine hospitalization data. METHODS We used a previously identified set of International Statistical Classification of Diseases and Related Health Problems, 10th Revision (ICD-10CA) and Canadian Classification of Interventions (CCI) codes to estimate rates of severe maternal morbidity in Canada (excluding Quebec) for 2003 to 2007 using the Discharge Abstract Database of the Canadian Institute for Health Information (CIHI). Rates and 95% confidence intervals were calculated by year and within each province and territory and contrasted using the chi-square or Fisher exact test. RESULTS The overall rate of severe maternal morbidity was 13.8 per 1000 deliveries (95% CI 13.6 to 14.0). Five provinces or territories had rates that were significantly higher than those in the rest of the country: Newfoundland and Labrador (19.0 per 1000; 95% CI 17.2 to 20.8), Saskatchewan (16.9 per 1000; 95% CI 15.9 to 18.0), Alberta (15.4 per 1000; 95% CI 14.9 to 15.9), Northwest Territories (22.5 per 1000; 95% CI 18.0 to 27.7), and Nunavut (20.2 per 1000; 95% CI 14.2 to 27.8). Rates of some illnesses declined (e.g., eclampsia rates decreased from 12.4 in 2003 to 5.7 per 10 000 deliveries in 2007, P<0.001), while others increased (e.g., postpartum hemorrhage with blood transfusion rates increased from 36.6 in 2003 to 44.3 per 10 000 deliveries in 2007, P<0.001). Interprovincial/territorial contrasts showed several disparities with respect to specific maternal illnesses. CONCLUSION The observed temporal trends and regional disparities in severe maternal morbidity may represent important population health phenomena, and further investigation is required to assess their importance.

Contribution of placenta accreta to the incidence of postpartum hemorrhage and severe postpartum hemorrhage.

OBJECTIVE: To quantify the contribution of placenta accreta to the rate of postpartum hemorrhage and severe postpartum hemorrhage. METHODS: All hospital deliveries in Canada (excluding Quebec) for the years 2009 and 2010 (N=570,637) were included in a retrospective cohort study using data from the Canadian Institute for Health Information. Placenta accreta included placental adhesion to the uterine wall, musculature, and surrounding organs (accreta, increta, or percreta). Severe postpartum hemorrhage included postpartum hemorrhage with blood transfusion, hysterectomy, or other procedures to control bleeding (including uterine suturing and ligation or embolization of pelvic arteries). Rates, rate ratios, population-attributable fractions (ie, incidence of postpartum hemorrhage attributable to placenta accreta), and 95% confidence intervals (CIs) were estimated. Logistic regression was used to quantify associations between placenta accreta and risk factors. RESULTS: The incidence of placenta accreta was 14.4 (95% CI 13.4–15.4) per 10,000 deliveries (819 cases among 570,637 deliveries), whereas the incidence of placenta accreta with postpartum hemorrhage was 7.2 (95% CI 6.5–8.0) per 10,000 deliveries. Postpartum hemorrhage among women with placenta accreta was predominantly third-stage hemorrhage (41% of all cases). Although placenta accreta was strongly associated with postpartum hemorrhage (rate ratio 8.3, 95% CI 7.7–8.9), its low frequency resulted in a small population-attributable fraction (1.0%, 95% CI 0.93–1.16). However, the strong association between placenta accreta and postpartum hemorrhage with hysterectomy (rate ratio 286, 95% CI 226–361) resulted in a population-attributable fraction of 29.0% (95% CI 24.3–34.3). CONCLUSION: Placenta accreta is too infrequent to account for the recent temporal increase in postpartum hemorrhage but contributes substantially to the proportion of postpartum hemorrhage with hysterectomy. LEVEL OF EVIDENCE: II

An analysis of antenatal hospitalization in Canada, 1991-2003.

Objectives: To examine the incidence and temporal trends of hospitalization during pregnancy, and provide additional information on maternal morbidity among Canadian women. Methods: A population-based cohort study was conducted using the Canadian Institute for Health Information’s Discharge Abstract Database between fiscal year 1991/92 and 2002/03. This database included antenatal hospitalizations for all hospital deliveries (N=3,103,365) in Canada except for those occurring in Manitoba and Quebec. Temporal trends, and variations in the non-delivery antenatal hospitalization ratio (per 100 deliveries) by maternal age and province or territory were quantified. Primary causes for antenatal hospitalization, the lengths of in-hospital stay, and changing pattern by maternal age and time period were compared. Results: The overall antenatal hospitalization ratio declined by 43%, from 24.0 per 100 deliveries in 1991/92 to 13.6 in 2002/03. Younger women tended to be hospitalized more frequently than older women: 27.1 per 100 deliveries for women aged less than 20 years and 21.5 per 100 deliveries for 20–24 years, respectively, compared to 11.5 per 100 for women aged 35–39 years. The antenatal hospitalization ratio varied greatly by province/territory – from 12.2 per 100 deliveries in Ontario to 30.7 in the Yukon. Threatened preterm labour, antenatal hemorrhage, hypertensive disorders, severe vomiting and diabetes remained the five most common causes for antenatal hospitalization, although the trends for the first four declined dramatically from 1991/92 to 2002/03. Younger women were more likely to be admitted for threatened preterm labour and severe vomiting, while older women were more likely to be admitted for antenatal hemorrhage and hypertensive disorders. Conclusions: The decline in antenatal hospitalization may reflect changes in management of pregnancy complications, e.g., transition from in-hospital care to out-of-hospital care, and introduction of antepartum home care programs. Information on interprovincial/territorial variations in antenatal hospitalization may be helpful in directing future maternal health care.

Delivery of breech presentation at term gestation in Canada, 2003-2011.

OBJECTIVE: To examine neonatal mortality and morbidity rates by mode of delivery among women with breech presentation at term gestation. METHODS: We carried out a population-based cohort study examining neonatal outcomes among term, nonanomalous singletons in breech presentation among all hospital deliveries in Canada (excluding Quebec) between 2003 and 2011. Mode of delivery was categorized into vaginal delivery, cesarean delivery in labor, and cesarean delivery without labor. Composite neonatal mortality and morbidity (death, assisted ventilation, convulsions, or specific birth injury) was the primary outcome. Logistic regression was used to estimate the independent effects of mode of delivery. RESULTS: The study population included 52,671 breech deliveries; vaginal deliveries increased from 2.7% in 2003 to 3.9% in 2011, and cesarean deliveries in labor increased from 8.7% to 9.8%. Composite neonatal mortality and morbidity rates at 37 weeks of gestation or greater after vaginal delivery were significantly higher than those after cesarean without labor (adjusted rate ratio 3.60, 95% confidence interval [CI] 2.50–5.15; adjusted rate difference 15.8/1,000 deliveries, 95% CI 9.2–25.2). Among women at 40 weeks of gestation or greater, neonatal mortality and morbidity rates after vaginal delivery were significantly higher than those after cesarean delivery without labor (adjusted rate ratio 5.39, 95% CI 2.68–10.8; adjusted rate difference 24.1/1,000 deliveries, 95% CI 9.2–53.8). Neonatal mortality and morbidity rates were also higher after caesarean delivery in labor. CONCLUSION: Among term, nonanomalous singletons in breech presentation at term, composite neonatal mortality and morbidity rates were significantly higher after vaginal delivery and cesarean delivery in labor compared with cesarean delivery without labor. LEVEL OF EVIDENCE: II

Contribution of prepregnancy body mass index and gestational weight gain to caesarean birth in Canada

BackgroundOverweight and obese women are known to be at increased risk of caesarean birth. This study estimates the contribution of prepregnancy body mass index (BMI) and gestational weight gain (GWG) to caesarean births in Canada.MethodsWe analyzed data from women in the Canadian Maternity Experiences Survey who had a singleton term live birth in 2005-2006. Adjusted odds ratios for caesarean birth across BMI and GWG groups were derived, separately for nulliparous women and parous women with and without a prior caesarean. Population attributable fractions of caesarean births associated with above normal BMI and excess GWG were calculated.ResultsThe overall caesarean birth rate was 25.7%. Among nulliparous and parous women without a previous caesarean birth, rates in obese women were 45.1% and 9.7% respectively, and rates in women who gained above their recommended GWG were 33.5% and 8.0% respectively. Caesarean birth was more strongly associated with BMI than with GWG. However, due to the high prevalence of excess GWG (48.8%), the proportion of caesareans associated with above normal BMI and excess GWG was similar [10.1% (95% CI: 9.9-10.2) and 10.9% (95% CI: 10.7-11.1) respectively]. Overall, one in five (20.2%, 95% CI: 20.0-20.4) caesarean births was associated with above normal BMI or excess GWG.ConclusionsOverweight and obese BMI and above recommended GWG are significantly associated with caesarean birth in singleton term pregnancies in Canada. Strategies to reduce caesarean births must include measures to prevent overweight and obese BMI prior to conception and promote recommended weight gain throughout pregnancy.

Temporal trends in maternal mortality in Canada II: estimates based on hospitalization data.

OBJECTIVES World Health Organization reports based on Canadian Vital Statistics data suggest a recent increase in maternal mortality rates in Canada. Since Vital Statistics data typically provide inaccurate estimates of maternal mortality, we examined temporal trends in Canada using hospitalization data. METHODS We identified in-hospital deaths among women aged 15 to 54 years from the Canadian Institute for Health Informations hospitalization database from 1996-1997 to 2007-2008. Maternal deaths during delivery were identified, and other in-hospital deaths were linked with prior pregnancy/delivery hospitalization records. Maternal mortality rates, 95% confidence intervals, and risk ratios (RRs) were estimated. RESULTS The maternal mortality rate in Canada was 9.2 per 100 000 deliveries (95% CI 7.6 to 11.2) in 1996 to 1999 and 9.0 per 100 000 deliveries (95% CI 7.4 to 10.9) in 2005 to 2007 (P for trend = 0.22). Older maternal age (RR 9.9 and 3.1 for ≥ 45 years and 40 to 44 years vs. 20 to 24 years), delivery by Caesarean section (RR 4.5 vs. vaginal delivery), and early gestation delivery (RR 20.1 and 5.9 for 20 to 27 weeks and 28 to 36 weeks vs. ≥ 37 weeks) were associated with higher maternal mortality. Cardiovascular diseases (rate 4.7 per 100 000 deliveries, 95% CI 3.9 to 5.5) were the most common diagnoses associated with maternal death. The rate of late maternal death (from 43 to 365 days after delivery) was 5.4 per 100 000 deliveries. CONCLUSION There was no increase in maternal mortality in Canada from 1996 to 2007. Increases observed in Canadian Vital Statistics data likely reflect improvements in the ascertainment of maternal death. Hospitalization data can serve as a timely and comprehensive source for monitoring trends in maternal mortality in Canada.