The association of persistent maternal hypotension with abnormal uterine Dopplers.

Objective: We aim to evaluate the association of persistent hypotension and abnormal placental hypoperfusion.

Methods: We performed a secondary analysis of the Nulliparous Pregnancy Outcomes Study of patients with a singleton gestation with persistent hypotension and complete uterine artery (UtA) data. Persistent hypotension was defined as systolic blood pressure <100 mmHg and/or diastolic blood pressure <60 mmHg at all three study visits between 6 0/7 and 29 6/7 weeks gestation. The primary outcome was abnormal UtA Dopplers (pulsatility index >95th percentile for gestational age or presence of a diastolic notch) measured between 18 0/7 and 23 6/7 weeks gestation. Univariable analyses were performed to evaluate demographic and clinical associations with the primary outcome. Multivariable analyses (MVAs) were performed to adjust for potential confounders selected a priori (age, insurance status, pre-pregnancy body mass index (BMI), and history of chronic hypertension).

Results: Five thousand two hundred and eighteen patients met inclusion criteria; 140 (2.7%) had persistent hypotension, 5078 (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 have a lower pre-pregnancy BMI, and more likely to use tobacco within 3 months of pregnancy. In unadjusted analysis, patients with persistent hypotension were more likely to have abnormal UtA Dopplers (45.0 vs. 35.3%, p value .017) but these findings did not persist in MVA (aOR 1.39, 95%CI 0.98, 1.95).

Conclusions: Patients with persistent hypotension were not at an increased risk of abnormal UtA Dopplers.