LAUSR

Background Given that pregnant women taking medications are excluded from clinical trials, real-world evidence is essential. We aimed to build a Canadian Mother-Child Cohort Active Surveillance Initiative (CAMCCO) and compare frequency of prematurity, low-birth-weight (LBW), major malformations, multiplicity, and gestational medication use across four provinces. Methods CAMCCO is a collaborative research infrastructure that uses real-world data from large provincial health care databases in Canada; developed with standardized methods to similarly construct population-based pregnancy/child cohorts with longitudinal follow-up by linking administrative/hospital/birth databases. CAMCCO also includes a common repository to i) share algorithms and case definitions based on diagnostic and procedural codes for research/training purpose, and ii) download aggregate data relevant to primary care providers, researchers, and decision makers. For this study, data from Quebec (1998–2015), Manitoba (1995–2019), Saskatchewan (1996–2020), and Alberta (2005–2018) are compared (Chi-square tests, p-values), and trends are calculated using Cochran-Armitage trend tests. Results Almost two-thirds (61%) of women took medications during pregnancy, mostly antibiotics (26%), asthma drugs (8%), and antidepressants (4%). Differences in the prevalence of prematurity (5.9–6.8%), LBW (4.0–5.2%), and multiplicity (1.0–2.5%) were statistically significant between provinces (p<0.001). Frequency of major malformations increased over time in Quebec (7–11%; p<0.001), Saskatchewan (5–11%; p<0.001), and Alberta (from 7–8%; p<0.001), and decreased in Manitoba (5–3%; p<0.001). Cardiovascular and musculoskeletal malformations were the most prevalent. Interpretation Medications are often used among Canadian pregnancies but adverse pregnancy outcomes vary across provinces. Digitized health data may help researchers and care providers understand the risk-benefit ratios related to gestational medication use, as well as province-specific trends.