Jocelyn Rouleau

Investigation of an increase in postpartum haemorrhage in Canada

Objective  To investigate the cause of a recent increase in hysterectomies for postpartum haemorrhage in Canada.

Amniotic-fluid embolism and medical induction of labour: a retrospective, population-based cohort study

BACKGROUND Amniotic-fluid embolism is a rare, but serious and often fatal maternal complication of delivery, of which the cause is unknown. We undertook an epidemiological study to investigate the association between amniotic-fluid embolism and medical induction of labour. METHODS We used a population-based cohort of 3 million hospital deliveries in Canada between 1991 and 2002 to assess the associations between overall and fatal rates of amniotic-fluid embolism and medical and surgical induction, maternal age, fetal presentation, mode of delivery, and pregnancy and labour complications. FINDINGS Total rate of amniotic-fluid embolism was 14.8 per 100,000 multiple-birth deliveries and 6.0 per 100,000 singleton deliveries (odds ratio 2.5 [95% CI 0.9-6.2]). Of the 180 cases of amniotic-fluid embolism in women with singleton deliveries during the study period, 24 (13%) were fatal. We saw no significant temporal increase in occurrence of amniotic-fluid embolism for total or fatal cases. Medical induction of labour nearly doubled the risk of overall cases of amniotic-fluid embolism (adjusted odds ratio 1.8 [1.3-2.7]), and the association was stronger for fatal cases (crude odds ratio 3.5 [1.5-8.4]). Maternal age of 35 years or older, caesarean or instrumental vaginal delivery, polyhydramnios, cervical laceration or uterine rupture, placenta previa or abruption, eclampsia, and fetal distress were also associated with an increased risk. INTERPRETATION Medical induction of labour seems to increase the risk of amniotic-fluid embolism. Although the absolute excess risk is low, women and physicians should be aware of this risk when making decisions about elective labour induction.

Influence of definition based versus pragmatic birth registration on international comparisons of perinatal and infant mortality: population based retrospective study

Objectives To examine variations in the registration of extremely low birthweight and early gestation births and to assess their effect on perinatal and infant mortality rankings of industrialised countries. Design Retrospective population based study. Setting Australia, Canada, European countries, and the United States for 2004; Australia, Canada, and New Zealand for 2007. Population National data on live births and on fetal, neonatal, and infant deaths. Main outcome measures Reported proportions of live births with birth weight/gestational age of less than 500 g, less than 1000 g, less than 24 weeks, and less than 28 weeks; crude rates of fetal, neonatal, and infant mortality; mortality rates calculated after exclusion of births under 500 g, under 1000 g, less than 24 weeks, and less than 28 weeks. Results The proportion of live births under 500 g varied widely from less than 1 per 10 000 live births in Belgium and Ireland to 10.8 per 10 000 live births in Canada and 16.9 in the United States. Neonatal deaths under 500 g, as a proportion of all neonatal deaths, also ranged from less than 1% in countries such as Luxembourg and Malta to 29.6% in Canada and 31.1% in the United States. Rankings of countries based on crude fetal, neonatal, and infant mortality rates differed substantially from rankings based on rates calculated after exclusion of births with a birth weight of less than 1000 g or a gestational age of less than 28 weeks. Conclusions International differences in reported rates of extremely low birthweight and very early gestation births probably reflect variations in registration of births and compromise the validity of international rankings of perinatal and infant mortality.

Epidemiology of Pregnancy-associated Venous Thromboembolism: A Population-based Study in Canada

OBJECTIVE To estimate the frequency of, and to identify risk factors for, pregnancy-associated venous thromboembolism (VTE), including deep vein thrombosis (DVT) and pulmonary embolism (PE) requiring hospitalization. METHODS We conducted a population-based cohort study (N = 3 852 569) using the Discharge Abstract Database of the Canadian Institute for Health Information (CIHI), for the fiscal years 1991-1992 to 2005-2006. All women with pregnancy-related hospitalizations in Canada (excluding Quebec and Manitoba) were identified. DVT and PE rates were calculated using the number of hospital deliveries (i.e., cohort of women at risk) as the denominator for the antepartum and peripartum (labour and delivery) hospitalizations and for postpartum readmissions. Risk factors for DVT/PE were identified using logistic regression. RESULTS During the antepartum, peripartum, and postpartum periods, 5.4, 7.2, and 4.3 VTE cases per 10,000 pregnancies, respectively were observed. The total incidence of DVT was 12.1 per 10,000 pregnancies (0.26 deaths per 100,000), and the rate for PE was 5.4 per 10,000 (0.96 deaths per 100,000). The strongest risk factors for DVT occurrence during the peripartum period were thrombophilia (adjusted odds ratio [aOR] 15.4; 95% CI 10.8-22.0), a past history of circulatory disease, and major puerperal infection, whereas those for PE were previous DVT (aOR 56.9; 95% CI 40.9-79.1), heart disease (aOR 43.4, 95% CI 35.0-53.9), antiphospholipid syndrome, past history of circulatory disease, transfusion, and major puerperal infection. CONCLUSION Cases of VTE and associated deaths occur most frequently during the peripartum period. Although mortality from pregnancy-associated VTE is low, maternal characteristics and other factors can be used to identify women at risk for VTE.

Association Between Maternal Chronic Conditions and Congenital Heart Defects A Population-Based Cohort Study

Background— This study quantifies the association between maternal medical conditions/illnesses and congenital heart defects (CHDs) among infants. Methods and Results— We carried out a population-based study of all mother-infant pairs (n=2 278 838) in Canada (excluding Quebec) from 2002 to 2010 using data from the Canadian Institute for Health Information. CHDs among infants were classified phenotypically through a hierarchical grouping of International Statistical Classification of Diseases and Related Health Problems, 10th Revision, Canada codes. Maternal conditions such as multifetal pregnancy, diabetes mellitus, hypertension, and congenital heart disease were defined by use of diagnosis codes. The association between maternal conditions and CHDs and its subtypes was modeled using logistic regression with adjustment for maternal age, parity, residence, and other factors. There were 26 488 infants diagnosed with CHDs at birth or at rehospitalization in infancy; the overall CHD prevalence was 116.2 per 10 000 live births, of which the severe CHD rate was 22.3 per 10 000. Risk factors for CHD included maternal age ≥40 years (adjusted odds ratio [aOR], 1.48; 95% confidence interval [CI], 1.39–1.58), multifetal pregnancy (aOR, 4.53; 95% CI, 4.28–4.80), diabetes mellitus (type 1: aOR, 4.65; 95% CI, 4.13–5.24; type 2: aOR, 4.12; 95% CI, 3.69–4.60), hypertension (aOR, 1.81; 95% CI, 1.61–2.03), thyroid disorders (aOR, 1.45; 95% CI, 1.26–1.67), congenital heart disease (aOR, 9.92; 95% CI, 8.36–11.8), systemic connective tissue disorders (aOR, 3.01; 95% CI, 2.23–4.06), and epilepsy and mood disorders (aOR, 1.41; 95% CI, 1.16–1.72). Specific CHD subtypes were associated with different maternal risk factors. Conclusions— Several chronic maternal medical conditions, including diabetes mellitus, hypertension, connective tissue disorders, and congenital heart disease, confer an increased risk of CHD in the offspring.

Patterns of infant mortality caused by major congenital anomalies

BACKGROUND We assessed the impact of recent advances in perinatal care on infant mortality due to congenital anomaly. METHODS Analysis of trends in congenital anomaly-attributed infant mortality, using the 1981-1995 Statistics Canadas birth and death records, with a total of 2,878,826 live births, 21,883 infant deaths, and 6, 908 infant deaths due to congenital anomalies. RESULTS Infant mortality due to major congenital anomaly decreased from 3.11 per 1, 000 live births in 1981 to 1.89 per 1,000 live births in 1995. Cause-specific infant mortality rates for anencephaly, spina bifida, other central nervous system anomalies, cardiovascular system anomalies, respiratory system anomalies, digestive system anomalies, certain musculoskeleton anomalies, urinary system anomalies, chromosomal anomalies, and multiple congenital anomalies were 0.20, 0.23, 0.27, 1.04, 0.24, 0.08, 0.22, 0.16, 0.22, and 0.13 per 1,000 live births, respectively, in 1981-1983, whereas corresponding rates were 0.07, 0.07, 0.18, 0.73, 0.25, 0.03, 0.12, 0.12, 0.26, and 0.06 per 1,000 live births, respectively, in 1993-1995. CONCLUSIONS Recent Canadian data show that infant deaths caused by major congenital anomalies have decreased significantly, but reductions varied substantially according to specific forms of anomalies.

Severe Maternal Morbidity in Canada, 2003 to 2007: Surveillance Using Routine Hospitalization Data and ICD-10CA Codes

OBJECTIVE To examine the feasibility of using routine labour and delivery hospitalization data and international classification of diseases (ICD-10CA) codes for carrying out surveillance of severe maternal morbidity in Canada. METHODS We identified ICD-10CA diagnosis codes and Canadian Classification of Interventions (CCI) procedure codes associated with severe maternal illness. Severe maternal morbidity rates in Canada (excluding Quebec) for the period 2003 to 2007 were estimated using the Discharge Abstract Database of the Canadian Institute for Health Information. Rates were compared across maternal age, parity, plurality, labour induction, delivery by Caesarean section, and other factors. Case fatality rates and length of hospitalization were also estimated. RESULTS Among the 1 336 356 women who delivered between 2003 and 2007, the rate of severe maternal morbidity was 13.8 per 1000 deliveries. The mean length of hospital stay for women with and without a severe illness was 5.4 days vs. 2.5 days, while the frequency of prolonged hospital stay (>or=7 days) was 19.8% vs. 1.8%, respectively (rate ratio 9.3; 95% CI 9.0 to 9.6). Case fatality rates differed significantly between women with and without a severe illness at 2.98 vs. 0.008 per 1000, respectively (rate ratio 392.8; 95% CI 200.3 to 700.4). Rates of severe maternal morbidity were higher among deliveries to older and nulliparous women and to those delivering twins or triplets. CONCLUSION Disease frequency, case fatality, and length of hospitalization patterns suggest that comprehensive and timely surveillance of severe maternal morbidity in Canada is feasible using the Canadian Institute for Health Information hospitalization data and ICD-10CA/CCI codes.

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 Late Preterm and Early Term Birth Rates in 6 High-Income Countries in North America and Europe and Association With Clinician-Initiated Obstetric Interventions

IMPORTANCE Clinicians have been urged to delay the use of obstetric interventions (eg, labor induction, cesarean delivery) until 39 weeks or later in the absence of maternal or fetal indications for intervention. OBJECTIVE To describe recent trends in late preterm and early term birth rates in 6 high-income countries and assess association with use of clinician-initiated obstetric interventions. DESIGN Retrospective analysis of singleton live births from 2006 to the latest available year (ranging from 2010 to 2015) in Canada, Denmark, Finland, Norway, Sweden, and the United States. EXPOSURES Use of clinician-initiated obstetric intervention (either labor induction or prelabor cesarean delivery) during delivery. MAIN OUTCOMES AND MEASURES Annual country-specific late preterm (34-36 weeks) and early term (37-38 weeks) birth rates. RESULTS The study population included 2,415,432 Canadian births in 2006-2014 (4.8% late preterm; 25.3% early term); 305,947 Danish births in 2006-2010 (3.6% late preterm; 18.8% early term); 571,937 Finnish births in 2006-2015 (3.3% late preterm; 16.8% early term); 468,954 Norwegian births in 2006-2013 (3.8% late preterm; 17.2% early term); 737,754 Swedish births in 2006-2012 (3.6% late preterm; 18.7% early term); and 25,788,558 US births in 2006-2014 (6.0% late preterm; 26.9% early term). Late preterm birth rates decreased in Norway (3.9% to 3.5%) and the United States (6.8% to 5.7%). Early term birth rates decreased in Norway (17.6% to 16.8%), Sweden (19.4% to 18.5%), and the United States (30.2% to 24.4%). In the United States, early term birth rates decreased from 33.0% in 2006 to 21.1% in 2014 among births with clinician-initiated obstetric intervention, and from 29.7% in 2006 to 27.1% in 2014 among births without clinician-initiated obstetric intervention. Rates of clinician-initiated obstetric intervention increased among late preterm births in Canada (28.0% to 37.9%), Denmark (22.2% to 25.0%), and Finland (25.1% to 38.5%), and among early term births in Denmark (38.4% to 43.8%) and Finland (29.8% to 40.1%). CONCLUSIONS AND RELEVANCE Between 2006 and 2014, late preterm and early term birth rates decreased in the United States, and an association was observed between early term birth rates and decreasing clinician-initiated obstetric interventions. Late preterm births also decreased in Norway, and early term births decreased in Norway and Sweden. Clinician-initiated obstetric interventions increased in some countries but no association was found with rates of late preterm or early term birth.

Variations in very preterm birth rates in 30 high-income countries: are valid international comparisons possible using routine data?

Concerns about differences in registration practices across countries have limited the use of routine data for international very preterm birth (VPT) rate comparisons.