Marital status, immigration, and reproductive health among adolescent mothers in Canada, 1990-2018: A population-based, observational study.

Immigrants to Canada increasingly come from regions where child marriage (<18 years) is prevalent. We described the prevalence, demographic characteristics, and reproductive health correlates of marriage among births to Canadian-born and foreign-born adolescent mothers. Using Canadian birth registrations from 1990 to 2018, marriage prevalence, parental birth region, and parental age gap were examined by maternal birthplace (Canada and 12 world regions) among births to mothers <18 years. Adjusted odds ratios (AORs) of preterm birth (PTB), small for gestational age (SGA), and repeat birth were estimated for the joint associations of adolescent maternal age group (<18-year, 18-19-year, and 20-24-year), marriage, and nativity status (n = 1,904,200). Depending on maternal birthplace, marital births represented 2.6% to 81.8% of births to mothers <18 years. Marriage among mothers giving birth at <18 years was associated with higher proportions of parents from the same birthplace and larger parental age gaps. AORs of PTB tended to increase with lower maternal age. AORs of SGA were generally higher among births to foreign-born mothers. Marriage was associated with lower AORs of PTB and SGA among births to Canadian-born mothers and PTB among births to foreign-born mothers in the older adolescent age groups, but no association existed in the <18-year group. Marriage was positively associated with repeat birth in all adolescent age groups, with stronger associations in the <18-year group. The reproductive health correlates of marriage are similar between births to Canadian-born and foreign-born mothers <18 years but some differ between births to mothers <18 years and those to older adolescent mothers.