Tracey Bushnik

Estimating the prevalence of infertility in Canada

BACKGROUND Over the past 10 years, there has been a significant increase in the use of assisted reproductive technologies in Canada, however, little is known about the overall prevalence of infertility in the population. The purpose of the present study was to estimate the prevalence of current infertility in Canada according to three definitions of the risk of conception. METHODS Data from the infertility component of the 2009–2010 Canadian Community Health Survey were analyzed for married and common-law couples with a female partner aged 18–44. The three definitions of the risk of conception were derived sequentially starting with birth control use in the previous 12 months, adding reported sexual intercourse in the previous 12 months, then pregnancy intent. Prevalence and odds ratios of current infertility were estimated by selected characteristics. RESULTS Estimates of the prevalence of current infertility ranged from 11.5% (95% CI 10.2, 12.9) to 15.7% (95% CI 14.2, 17.4). Each estimate represented an increase in current infertility prevalence in Canada when compared with previous national estimates. Couples with lower parity (0 or 1 child) had significantly higher odds of experiencing current infertility when the female partner was aged 35–44 years versus 18–34 years. Lower odds of experiencing current infertility were observed for multiparous couples regardless of age group of the female partner, when compared with nulliparous couples. CONCLUSIONS The present study suggests that the prevalence of current infertility has increased since the last time it was measured in Canada, and is associated with the age of the female partner and parity.

The direction of the difference between Canadian and American erythrocyte folate concentrations is dependent on the assay method employed: a comparison of the Canadian Health Measures Survey and National Health and Nutrition Examination Survey.

Fortification of select grain products with folic acid and periconceptional supplementation recommendations in Canada and the USA have improved folate status, and have been associated with a reduced risk of neural tube defects. In the present study, we aimed to conduct a comparison of erythrocyte folate concentrations from the 2007-9 Canadian Health Measures Survey (CHMS) and the 2007-8 US National Health and Nutrition Examination Survey (NHANES). Erythrocyte folate concentration was assessed in participants aged 6-79 years (CHMS, n 5248; NHANES, n 7070). To account for different folate assays employed - Immulite 2000 immunoassay (CHMS) and microbiological assay (NHANES) - a conversion equation was generated (n 152 adults) to adjust the CHMS data. t Tests were used to examine country differences. Median Canadian erythrocyte folate concentrations (method-adjusted) were lower than those of Americans (988 and 1100 nmol/l, respectively), but unadjusted median Canadian erythrocyte folate concentrations were higher (1250 nmol/l). The upper 95% CI boundary of the method-adjusted Canadian erythrocyte folate distribution overlapped that of the American erythrocyte folate concentrations, while the lower 95% CI boundary of the method-adjusted Canadian erythrocyte folate data was below the American distribution. In summary, the fact that erythrocyte folate concentrations were either higher or lower in Canadians compared with Americans, depending on whether an adjustment was made to account for assay differences, suggests that caution must be exercised in evaluating erythrocyte folate data from different countries because analytical methods are not readily comparable. Furthermore, we cannot unequivocally conclude that there are true differences in erythrocyte folate concentrations between the Canadian and American populations in the post-fortification era.

Comparison of black-white disparities in preterm birth between Canada and the United States

Background: A higher risk of preterm birth among black women than among white women is well established in the United States. We compared differences in preterm birth between non-Hispanic black and white women in Canada and the US, hypothesizing that disparities would be less extreme in Canada given the different historical experiences of black populations and Canada’s universal health care system. Methods: Using data on singleton live births in Canada and the US for 2004–2006, we estimated crude and adjusted risk ratios and risk differences in preterm birth (< 37 wk) and very preterm birth (< 32 wk) among non-Hispanic black versus non-Hispanic white women in each country. Adjusted models for the US were standardized to the covariate distribution of the Canadian cohort. Results: In Canada, 8.9% and 5.9% of infants born to black and white mothers, respectively, were preterm; the corresponding figures in the US were 12.7% and 8.0%. Crude risk ratios for preterm birth among black women relative to white women were 1.49 (95% confidence interval [CI] 1.32 to 1.66) in Canada and 1.57 (95% CI 1.56 to 1.58) in the US (p value for heterogeneity [pH] = 0.3). The crude risk differences for preterm birth were 2.94 (95% CI 1.91 to 3.96) in Canada and 4.63 (95% CI 4.56 to 4.70) in the US (pH = 0.003). Adjusted risk ratios for preterm birth (pH = 0.1) were slightly higher in Canada than in the US, whereas adjusted risk differences were similar in both countries. Similar patterns were observed for racial disparities in very preterm birth. Interpretation: Relative disparities in preterm birth and very preterm birth between non-Hispanic black and white women were similar in magnitude in Canada and the US. Absolute disparities were smaller in Canada, which reflects a lower overall risk of preterm birth in Canada than in the US in both black and white populations.

Comparing Guidelines for Statin Treatment in Canada and the United States.

Background New guidelines for cardiovascular disease risk assessment and statin eligibility have recently been published in the United States by the American College of Cardiology and the American Heart Association (ACC-AHA). It is unknown how these guidelines compare with the Canadian Cardiovascular Society (CCS) recommendations. Methods and Results Using data from the Canadian Health Measures Survey 2007–2011, we estimated the cardiovascular disease risk and proportion of the Canadian population, aged 40 to 75 years without cardiovascular disease, who would theoretically be eligible for statin treatment under both the CCS and ACC-AHA guidelines. The survey sample used (n=1975) represented 13.1 million community dwelling Canadians between the ages of 40 and 75 years. In comparing the CVD risk assessment methods, we found that calculated CVD risk was higher based on the CCS guidelines compared with the ACC-AHA guidelines. Despite this, a similar proportion and number of Canadians would be eligible for statin treatment under the 2 sets of recommendations. Some discordance in recommendations was found within subgroups of the population, with the CCS guidelines recommending more treatment for individuals who are younger, with a family history of CVD, or with chronic kidney disease. The ACC-AHA recommend more treatment for people who are older (age 60+ years). These results likely overestimate the treatment rate under both guidelines because, in primary prevention, a clinician–patient discussion must occur before treatment and determines uptake. Conclusions Implementing the ACC-AHA lipid treatment guidelines in Canada would not result in an increase in individuals eligible for statin treatment. In fact, the proportion of the population recommended for statin treatment would decrease slightly and be targeted at different subgroups of the population.

Paternal education and adverse birth outcomes in Canada

Background Research on predictors of adverse birth outcomes has focused on maternal characteristics. Much less is known about the role of paternal factors. Paternal education is an important socioeconomic marker that may predict birth outcomes over and above maternal socioeconomic indicators. Methods Using data from the 2006 Canadian Birth-Census Cohort, we estimated the associations between paternal education and preterm birth, small-for-gestational-age (SGA) birth, stillbirth and infant mortality in Canada, controlling for maternal characteristics. Binomial regression was used to estimate risk ratios and risk differences for adverse birth outcomes associated with paternal education, after controlling for maternal education, age, marital status, parity, ethnicity and nativity. Results A total of 131 285 singleton births were included in the present study. Comparing the lowest to the highest paternal education category, adjusted risk ratios (95% CIs) were 1.22 (1.10 to 1.35) for preterm birth, 1.13 (1.03 to 1.23) for SGA birth, 1.92 (1.28 to 2.86) for stillbirth and 1.67 (1.01 to 2.75) for infant mortality. Consistent patterns of associations were observed for absolute risk differences. Conclusions Our study suggests that low paternal education increases the risk of adverse birth outcomes, and especially of fetal and infant mortality, independently from maternal characteristics.

Adverse birth outcomes and infant mortality according to registered First Nations status and First Nations community residence across Canada

ObjectiveStudies of perinatal health outcomes in Canadian First Nations populations have largely focused on limited geographical areas and have been unable to examine outcomes by registered status and community residence. In this study, we compare rates of adverse birth outcomes among First Nations individuals living within vs. outside of First Nations communities and those with vs. without registered status.MethodsData included 13,506 singleton pregnancies from the 2006 Canadian Birth-Census Cohort. Outcomes examined included preterm birth (PTB), small- and large-for-gestational-age birth (SGA, LGA), stillbirth, overall infant mortality, and neonatal and postneonatal mortality. Risk ratios (RRs) were estimated with adjustment for maternal age, education, parity, and paternal education.ResultsMothers living in First Nations communities and those with status had elevated adjusted risks of LGA (RR for First Nations community residence = 1.22, 95% CI = 1.09–1.35; RR for status = 1.50, 95% CI = 1.16–1.93). Rates of SGA were significantly lower among mothers with status (adjusted RR = 0.62, 95% CI = 0.44–0.86). Rates of PTB did not vary substantially by residence or by status. Adjusted differences in fatal outcomes could not be estimated, owing to small cell sizes. However, mothers living in First Nations communities had higher crude rates of infant mortality (10.9 vs. 7.7 per 1000), particularly for neonatal mortality (6.1 vs. 2.9).ConclusionFuture investigations should explore risk factors, including food security and access to health care services, that may explain disparities in SGA and LGA by status and residence within First Nations populations.RésuméObjectifLes études examinant les issues de santé périnatale des populations canadiennes des Premières Nations examinent, pour la plupart d’entre elles, des étendues géographiques limitées. De plus, ces études n’ont pas pu examiner les issues de santé périnatale selon la statut (statut d’Indien inscrit), ni selon la résidence dans les communautés des Premières Nations. Dans cette étude, notre objectif est d’examiner la prévalence des diverses issues néonatales selon la résidence dans une communauté des Premières Nations ainsi que selon le statut.Méthodes13 506 grossesses simples de la cohorte canadienne de naissance du Recensement de 2006 ont été examinées. Les complications néonatales étudiées comprenaient la naissance prématurée, le nouveau-né avec un petit ou un grand poids pour l’âge gestationnel (PAG, GAG), la mortinaissance, la mortalité infantile totale ainsi que la mortalité néonatale et post-néonatale. Les données ont été examinées selon la résidence dans une communauté des Premières Nations ou non et selon l’obtention ou non de statut. Les risques relatifs (RR) ont été estimés avec l’ajustement pour l’âge maternel, le niveau de scolarité de la mère, la parité et le niveau de scolarité du père.RésultatsLes mères habitant dans une communauté des Premières Nations ainsi que celles qui avaient de statut avaient un risque ajusté élevé de nouveau-né GAG (RR pour la résidence dans une communauté des Premières Nations = 1,22, IC de 95 % : 1,09, 1,35; RR pour le statut = 1,50, IC de 95 % : 1,16, 1,93). La prévalence de nouveau-nés PAG était significativement plus basse chez les mères ayant du statut (RR ajusté = 0,62, IC de 95 % : 0,44, 0,86) comparativement à celles n’ayant pas de statut. La prévalence des naissances prématurées n’a pas significativement varié selon la résidence, ni selon le statut. Les différences ajustées pour les issues fatales n’ont pas pu être estimées en raison de la taille de l’échantillon. Cependant, les mères qui habitaient dans une communauté des Premières Nations avaient un taux brut de mortalité infantile plus élevé (10,9 par 1 000, c. 7,7 par 1000), particulièrement pour la mortalité néonatale (6,1 c. 2,9), comparativement à celles n’habitant pas dans une communauté des Premières Nations.ConclusionDe futures études sont nécessaires afin d’examiner les facteurs, tel que la sécurité alimentaire et l’accès aux services de santé, pouvant expliquer les différences de prévalence de nouveau-nés PAG et GAG selon le statut et la résidence au sein des populations des Premières Nations.

Adverse birth outcomes in relation to maternal marital and cohabitation status in Canada

PURPOSE An increasing percentage of children are born to couples who cohabit but are not legally married. Using data from a nationally representative Canadian sample, we estimated associations of maternal marital and cohabitation status with stillbirth, infant mortality, preterm birth (PTB), and small- and large-for-gestational-age (SGA and LGA) birth. METHODS The 2006 Canadian Birth-Census Cohort was created by linking birth registration data with the 2006 long-form census. We used log-binomial regression to estimate risk ratios (RRs) for adverse birth outcomes associated with being single or living with a common-law partner. Analyses were adjusted for maternal age and education. RESULTS Data were analyzed for 130,931 singleton births. Adjusted RRs (95% confidence intervals) for single mothers compared with married mothers were 1.92 (1.51-2.42) for stillbirth, 2.08 (1.55-2.81) for infant mortality, 1.36 (1.27-1.46) for PTB, 1.31 (1.22-1.39) for SGA birth, and 0.95 (0.90-1.01) for LGA birth. Adjusted RRs for cohabiting mothers compared with married mothers were 0.93 (0.74-1.16) for stillbirth, 1.05 (0.81-1.35) for infant mortality, 1.09 (1.03-1.15) for PTB, 1.05 (0.99-1.10) for SGA birth, and 0.96 (0.92-1.00) for LGA birth. CONCLUSIONS In a nationally representative Canadian birth cohort, cohabiting and legally married women experienced similar birth outcomes, but most outcomes for single women were substantially worse.