347 Hyperemesis Gravidarum: Investigating Pregnancy Outcomes by Severity and Time of Diagnosis

With inconsistencies regarding the possible effect of hyperemesis gravidarum on the course of pregnancy, this research aimed to study the association between hyperemesis gravidarum and pregnancy outcomes, while addressing the trimester of diagnosis and severity of the disease. A population-based retrospective cohort study was conducted, including all singleton deliveries of mothers from the largest health maintenance organization in the country, in a single tertiary hospital between the years 1991-2021. Incidence of adverse pregnancy outcomes was compared between pregnancies with and without hyperemesis gravidarum diagnosis, including preterm birth, low birth weight, cesarean delivery, and perinatal mortality. Severe cases were defined as hyperemesis gravidarum with metabolic disturbances. Multivariable Generalized Estimation Equation binary models were used to study the association between maternal hyperemesis gravidarum, trimester of diagnosis and severity, and the studied outcomes while adjusting for smoking, nulliparity, fertility treatments, ethnicity, gender, maternal age, and maternal recurrence in the cohort. The study population included 232,476 pregnancies, of which 3227 (1.4%) were complicated with hyperemesis gravidarum. Women with hyperemesis gravidarum were more likely to deliver preterm (adjusted OR=1.30, 95%CI 1.14-1.47), a newborn with low birth weight (adj. OR=1.52, 95%CI 1.16-1.98, only if diagnosed in the second trimester), and to have a cesarean delivery (adj. OR=1.22, 95%CI 1.10-1.35). They were less likely to experience perinatal mortality (adj. OR=0.54, 95%CI 0.31-0.93, among mild cases only). A dose-response association was observed between preterm birth and hyperemesis gravidarum severity (Table). Hyperemesis gravidarum is associated with an increased risk for preterm birth, low birth weight, and cesarean delivery, specifically among women diagnosed during the second trimester. However, it is associated with a lower risk for perinatal mortality.