Influence of gestational weight gain and BMI on cesarean delivery risk in adolescent pregnancies

Obesity and excessive gestational weight gain (GWG) increase cesarean delivery (CD) risk; however, their influence on teen pregnancies is less clear. We describe the influence of GWG and pre-pregnancy body mass index (BMI) on primary CD (PCD) risk in adolescent compared with adult pregnancies.

Population-based cohort study of Ohio births (2006 to 2012), n=1 034 552. Analyses were limited to 251 398 singleton live births in term (37 to 42 weeks) primiparas. Multivariate logistic regression estimated the association between BMI, GWG and CD risk in teens compared with adults (20 to 34 years), adjusting for maternal race, smoking status and labor induction.

The primary cesarean rate (PCD) for primiparous women was 25.6%. It was lower for adolescents (17% <15 years, 17% 15 to 17 years, 19% 18 to 19 years) compared with adults (26%, P<0.001). The PCD rate increased with excessive (29%) vs Institute of Medicine (IOM)-recommended GWG (20%). The PCD rate was also increased in mothers who were overweight (29%), and obese (39%) vs those with normal pre-pregnancy BMI (20%, P<0.001). The lowest PCD rate (11.6%) observed in normal weight teens <18 years was with appropriate GWG (adjusted odds ratio (aOR) 0.61; 95% CI 0.54 to 0.69). Compared with adults, teens have 43% lower PCD risk (aOR 0.57; 95% CI 0.55 to 0.60). Excessive GWG increased the risk for PCD in adults by 64% (aOR 1.64; 95% CI 1.59 to 1.68). Excessive GWG increased PCD in the highest risk groups, obese adults (aOR 1.24; 1.17 to 1.32) and obese teens (aOR 1.26; 95% CI 1.08 to 1.46).

Excessive GWG increases the risk of PCD. Young maternal age was protective of this effect. However, excessive GWG increased PCD risk in both teen and adult mothers. To reduce the primary cesarean rate, efforts should target interventions to promote optimal GWG, especially in those at highest risk, obese women of all ages.