(583) Earlier intervention for acute post-neuraxial hypotension in pregnancies with obesity may improve fetal acidemia

Prior studies have demonstrated an association between obesity and fetal acidemia. We aimed to determine if pregnancies with obesity that experienced acute post-neuraxial hypotension were associated with fetal acidemia and if earlier intervention may be indicated.

Study Design:

Retrospective cohort study of non-labor, non-anomalous, term, singleton births via cesarean delivery under neuraxial from 2013-2019 that experienced acute post-neuraxial hypotension (systolic blood pressure (BP) < 100 mmHg recorded prior to delivery). We compared rates of adverse outcomes in pregnancies with obesity (BMI > 30 kg/m²) or without (BMI < 30 kg/m²). Primary outcome was umbilical artery (UA) pH < 7.1. Chi-square and multivariate regression tests determined the strength of association.

Results:

Of 2851 patients with acute post-neuraxial hypotension, 1432 (50.23%) had obesity while 1432 (49.77%) did not. Pregnancies with obesity were more likely to have diabetes and hypertensive disorders, and more often received combined spinal-epidural analgesia. After adjusting for confounders including maternal BMI, type of neuraxial anesthesia, and hypertensive disorders, an acute post-neuraxial hypotension in pregnancies complicated by obesity was associated with UA pH < 7.1 (aOR 2.07 [1.25-3.42]) and umbilical cord base deficit > 12 (aOR 2.52 [1.18-5.35]). When assessing the relationship between post-neuraxial systolic BP nadir and UA pH, pregnancies without obesity have decreased probability of UA pH > 7.1 at a systolic BP of 100 mg Hg whereas pregnancies with obesity have a decreased probability of UA pH > 7.1 at a systolic BP of 120 mm Hg. (Figure 1, p < 0.01)

Conclusion:

Findings suggest that in the setting of maternal obesity, acute post-neuraxial hypotension is associated with a greater odds of UA pH < 7.1. Earlier intervention for acute post-neuraxial hypotension in pregnancies with obesity may be warranted.