(641) Association of Maternal Hypotension with Abnormal Uterine Artery Dopplers and Small for Gestational Age Neonates

Objective: To evaluate the association of abnormal uterine artery (UtA) dopplers in patients with persistent hypotension with delivery of a small for gestational age (SGA) neonate. We hypothesize that abnormal blood flow to the uterus may result in smaller neonates.

Study Design: This was a secondary analysis of the Nulliparous Pregnancy Outcomes Study: Monitoring Mothers-to-Be of patients with a singleton gestation at > 24 weeks with abnormal UtA dopplers (defined as pulsatility index > 95th percentile for gestational age or presence of a diastolic notch) between 18 weeks 0 days and 23 weeks 6 days gestation. Persistent hypotension was defined as systolic blood pressure < 100 mmHg and/or diastolic blood pressure < 60mmHg at all 3 study visits between 6 weeks 0 days and 29 weeks and 6 days gestation. The primary outcome was delivery of an SGA neonate. Univariable analyses were performed to evaluate demographic and clinical associations with the primary outcome. Multivariable analyses were performed to adjust for potential confounders selected a priori (age, race and ethnicity, insurance status, pre-pregnancy body mass index (BMI), and history of chronic hypertension).

Results: 5,092 patients met inclusion criteria; 137 (2.7%) had persistent hypotension, 4,955 (97.3%) did not. Patients in the hypotension group were less likely to be of White race and Asian ethnicity, and more likely to have public insurance and a lower pre-pregnancy BMI, and less likely to use tobacco within 3 months of pregnancy (Table 1). Patients with persistent hypotension and abnormal UtA dopplers were more likely to deliver an SGA neonate (11.8 vs. 18.2%, p-value 0.025) but this did not persist in multivariable analysis (aOR 1.43, 95% CI 0.91, 2.24). In univariable analysis of secondary outcomes, the hypotension group had a lower median birth weight (3,323 vs. 3,239 grams, p-value 0.01) (Table 2).

Conclusion: In patients with abnormal UtA dopplers, persistent hypotension was not associated with an increased risk of an SGA neonate.