Obstetric Outcomes in Adolescents Related to Body Mass Index and Compared with Low-Risk Adult Women

Objective: To evaluate in adolescents the association between body mass index (BMI) and obstetric outcomes and to determine whether the outcomes in the BMI groups of adolescents differ from those of a low-risk population of adult women. Materials and Methods: This is a nationwide population-based register study. Obstetric outcomes of 31,386 singleton primiparous adolescents were evaluated in relation to BMI classes. Furthermore, the outcomes of the adolescents and 178,844 normal weight, nonsmoking, singleton primiparous women, 25-29 years old with no known comorbidity, defined as standard women, were compared. Multiple logistic regression models were used. Results are presented as crude odds ratios (ORs) or adjusted ORs and with a 95% confidence interval. Results: Compared with normal weight adolescents, obese adolescents had a lower chance of a normal vaginal delivery (VD)76% versus 85% [adjusted OR 0.61 (0.55-0.68)], a higher risk for acute cesarean section (CS)8.9% versus 4.5% [adjusted OR 2.45 (2.08-2.88)], and stillbirth0.7% versus 0.2% [adjusted OR 3.17 (1.74-5.77)]. Compared with standard women, overweight adolescents had a higher chance of a normal VD82% versus 75% [crude OR 1.53 (1.44-1.64)] and a lower risk for acute CS6.3% versus 7.1% [crude OR 0.85 (0.76-0.95)]. Obese adolescents had a lower risk for instrumental VD8% versus 13% [crude OR 0.61 (0.53-0.71)] and obstetric anal sphincter injury1% versus 3% [crude OR 0.38 (0.26-0.57)]. Conclusion: Several adverse obstetric outcomes were obesity related among adolescents. Overweight adolescents seemed to have better obstetric outcomes than standard women, something to consider when optimizing resources for women during pregnancy and delivery.