Comparison of Risk Factors and Neonatal Outcomes Among Women With a Spontaneous Versus Iatrogenic Preterm Birth [24O

Abstract

INTRODUCTION: While spontaneous preterm birth (sPTB) has been trending down, iatrogenic preterm birth (iPTB) has been trending up. The purpose of this study is to examine the difference in risk factors and neonatal outcomes among women with a sPTB vs iPTB to identify areas for intervention. METHODS: Retrospective cohort study from 1/2012-12/2014 of singleton pregnancies without a history of prior sPTB undergoing routine cervical length screening between 18 0/7-23 6/7 weeks. Women were included if they delivered less than 37 weeks. RESULTS: Of 3678 women screened, 200 women (5.4%) had a PTB; 114 (57%) sPTB and 86 (43%) iPTB. Women with sPTB were on average younger than those with iPTB (27.3 ±6.2 vs 29.5 ±6.4, p=0.019). Women with iPTB were more likely to have a BMI of at least 30 (39% vs 23%, p=0.021), have a hypertensive disorder of pregnancy (74% vs 9%, p < 0.001), and have fetal growth restriction (14% vs 0%, p < 0.001) than women with sPTB. Women with a sPTB delivered earlier, with a mean gestational age of 32.7±4.9 vs 34.1±2.7 weeks (p=0.015), and an increased incidence of delivery less than 28 weeks (17% vs 4%, p=0.003). However, infants born from an iPTB were more likely to require intensive care admission (71% vs 54%, p=0.016). The incidence of neonatal morbidity was similar. CONCLUSION: Although sPTB tends to result in an earlier gestational age of delivery, iPTB is a more significant source of neonatal intensive care admission. Maternal obesity and hypertensive disorders are major modifiable risk factors for iPTB.