Objective: Few Canadian studies have examined the association between adolescent pregnancy and adverse pregnancy outcomes. The objective of this cohort study was to characterize the association between adolescent pregnancy and specific adverse maternal, obstetrical, and neonatal outcomes, as well as maternal health behaviours.
Methods: We conducted a retrospective population-based cohort study of all singleton births in Ontario between January 2006 and December 2010, using the Better Outcomes Registry and Network database. Outcomes for pregnant women < 20 years of age (adolescent) were compared with those of women 20 to 35 years old (adult).
Results: This study included 551 079 singleton birth records, 23 992 (4.35%) of which derived from adolescent pregnancies. Adolescents had a higher rate of smoking and substance use than adult women and were within the lowest education and family income quintiles. Adolescents had a significantly lower risk of gestational hypertension (adjusted relative risk [aRR] 0.73) and gestational diabetes (aRR 0.34), placental abruption (aRR 0.80), and placenta previa (aRR 0.36), but their risk of preterm premature rupture of membranes was significantly higher (RR 1.16). Adolescents had a significantly higher proportion of spontaneous vaginal delivery (aRR 1.76), significantly lower rates of use of epidural analgesia (aRR 0.93), of Caesarean section (aRR 0.57), and of assisted vaginal delivery (aRR 0.76), but a significantly higher risk of emergency CS (aRR 1.31). Neonates with an adolescent mother had significantly higher risks of admission to NICU (aRR 1.08) and very preterm birth (aRR 1.16). There was no significant difference between the two groups in rates of small for gestational age babies, low birth weight, preterm birth, and fetal death. Adolescents had significantly lower rates of prenatal class attendance, prenatal visits in the first trimester, and breastfeeding.
Conclusion: This large Canadian cohort study confirms that, compared with adults, adolescents have improved outcomes such as lower rates of gestational hypertension, gestational diabetes, antepartum hemorrhage, and operative deliveries. However, adolescents also have higher sociodemographic risk factors and seek prenatal care later than adults. These risk factors in combination with young age, lead to other important maternal, obstetrical, and neonatal adverse outcomes. These findings highlight the importance of multidisciplinary prenatal management in the adolescent population to address their high-risk needs, to ensure healthy pregnancies, and to reduce adverse perinatal outcomes.