There is limited nationwide data describing trends in teenage pregnancies and their risk of adverse outcomes. This study aimed to analyze teenage pregnancy prevalence over fifteen years and the risks for adverse maternal outcomes and preterm delivery. A repeat cross-sectional study using the National Inpatient Sample analyzed delivery hospitalizations from 2000-15. Trends in teenage pregnancies were analyzed using Joinpoint Regression with average annual percent change (AAPC). Adverse outcomes including placental abruption, cesarean delivery, hypertensive disorders of pregnancy (HDP), postpartum hemorrhage (PPH), preterm delivery, and severe maternal morbidity (SMM) as defined by the CDC were stratified by maternal age groups. Log linear models were fit to assess the relative risk of maternal age on adverse outcomes adjusting for sociodemographic, medical, obstetric and hospital factors. From 2000-15, 9.5% of delivery hospitalizations (6.0 of 62.8 million) were to women 11-19 years old. Teenage pregnancy decreased during the study period: 11-14 years old by -7.3% AAPC (95% CI -8.2%, -6.4%) and 15-19 years old by -4.3% AAPC (95% CI -5.0%, -3.6%) (Figure). Teenage pregnancies were at higher risk of preterm delivery (11-14 years old aRR 1.68, 95% CI: 1.65, 1.71; 15-19 years old aRR 1.21, 95% CI: 1.20, 1.21) compared to patients 25 to 29 years old. Similarly, 11-14 year olds were at significantly elevated risk of HDP (aRR 1.76, 95% CI 1.73, 1.80), PPH (aRR 1.16, 95% CI 1.12, 1.20), and SMM (aRR 1.44, 95% 1.37, 1.50) when compared to women 25 to 29 (Table). Teen patients 11-19 years old had lower risk of cesarean delivery and similar risk for placental abruption. While teen pregnancy decreased over the study period, deliveries to patients 11-19 years old were associated with significantly increased risk for hypertensive disorders of pregnancy, preterm delivery, and SMM. Increased attention to risk for these complications may be warranted during prenatal and peridelivery care.View Large Image Figure ViewerDownload Hi-res image Download (PPT)