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305 Influence of parity on perinatal mortality in adolescent pregnancy Anuradha Devabhaktuni, Ashley E. Skeith, Rachel A. Pilliod, Aaron B. Caughey, Amy M. Valent Oregon Health & Science University, Portland, OR OBJECTIVE: Multiparous women demonstrate faster physiologic pregnancy adaptations and deliver infants with higher birthweights than nulliparous women, suggesting a more favorable, primed environment after a first pregnancy. We sought to determine if these findings are consistent in adolescent pregnancies by comparing perinatal mortality in multiparous adolescents compared to nulliparous adolescents. STUDY DESIGN: We conducted a retrospective cohort study of all term, singleton, non-anomalous births in women less than 20 years old, comparing perinatal mortality (intrauterine fetal [IUFD] and neonatal demise [NND]) between multiparous (parity1⁄41, with no history of abortion) and nulliparous (parity 1⁄4 0) women who delivered in California between 2007 and 2011. Chi squared tests and multivariable logistic regression analyses were performed to determine the frequencies and strength of association of perinatal mortality and parity, adjusting for maternal age, race, BMI, pregestational diabetes, chronic hypertension, fetal sex, smoking status, and socioeconomic status. A p-value less than 0.05 was used to indicate statistical significance. RESULTS: Of 202,658 total deliveries, 172,561 (85.1%) were nulliparous and 30,097 (14.9%) were multiparous with one prior birth. When compared to multiparous adolescents, nulliparous adolescents had significantly increased odds of IUFD (aOR 6.44, 95% CI 4.0910.14), neonatal jaundice (aOR 1.45, 95% CI 1.40-1.52), NICU admission (aOR 1.24, 95% CI 1.18-1.30) and Apgar score less than 7 at 5 minutes (aOR 2.14, 95% CI 1.76-2.61) even after adjusting for relevant covariates. Compared to multiparous women, nulliparous women also had increased odds of small-for-gestational (SGA) age infants at <10% birth weight (aOR 1.60, 95% CI 1.39-1.83), SGA <5% birth weight (aOR 1.67, 95% CI 1.342.08), and SGA <3% birth weight (aOR 2.18, 95% CI 1.57-3.04). However, nulliparity was associated with a decreased odds of preterm delivery <37 weeks (aOR 0.76, 95% CI 0.73-0.79) and <32 weeks (aOR 0.82, 95% CI 0.77-0.88). CONCLUSION: Perinatal morbidity and mortality is significantly greater in nulliparous adolescents compared to multiparous adolescents, however, nulliparity is protective against preterm birth in this population. These findings suggest a potential role for increased surveillance in nulliparous adolescents to improve neonatal outcomes.