Twinning and risk of stillbirth subtypes in pediatric mothers

We sought to estimate levels of risk for stillbirth subtypes associated with twin gestations among pediatric mothers (10-14 years). Analysis was on twin pregnancies covering the period 1989 to 2000 in the United States. We classified stillbirth as term, preterm, small-for-gestational-age (SGA) or preterm-SGA. We then assessed the risks of these stillbirth subtypes in pediatric mothers using two comparison groups consisting of women aged 15 to 19 years old (adolescent mothers) and 20 to 24 years old (mature mothers). Adjusted risk estimates were by means of hazard ratios generated from a Cox proportional hazards regression model. We adjusted for dependence of observations within twin clusters using the robust sandwich estimator. The rate of stillbirth was highest among pediatric mothers (56/1000), followed by adolescent gravidas (29/1000) and lowest in mature mothers (20/1000; p for trend < .01). Overall, preterm stillbirth was the most frequent stillbirth phenotype while term stillbirth was the least frequent. Not a single case of term stillbirth was recorded in pediatric mothers. Among pediatric gravidas, the risk for preterm stillbirth was more than tripled (adjusted hazard ratio [AHR] = 3.4; 95% confidence interval [CI] = 2.5-4.6), and that of preterm-SGA stillbirth more than doubled (AHR = 2.6; 95% CI = 1.8-3.7) that of mature mothers respectively. The 30% risk elevation for SGA stillbirth among pediatric mothers was not found to be statistically significant (AHR = 1.1; 95% CI = 0.3-4.3). Pediatric motherhood is a risk factor for stillbirth in twin gestation, especially, preterm and preterm-SGA stillbirth phenotypes. Prevention of stillbirth among this category of mothers should target the period preceding full term.