The association of intrapartum oral labetalol for preeclampsia with severe features and risk of cesarean delivery: a retrospective cohort study

To evaluate if the use of intrapartum oral labetalol vs. no antihypertensive medication additions for severe preeclampsia (PreE with SF) for sustained oral blood pressure control decreases the risk of cesarean. This was a retrospective cohort study of patients who underwent a trial of labor of a non-anomalous, singleton gestation at ≥ 34 weeks gestational age with preeclampsia with severe features. The exposure was intrapartum oral labetalol compared to no oral antihypertensive medication. The use of intrapartum labetalol was defined as the initiation of labetalol in labor for preeclampsia with severe features. The primary outcome was the need for cesarean. Univariable analyses were performed to evaluate the association of oral labetalol therapy and need for cesarean. Variables that had an independent association with the outcome were determined a priori and included in the multivariable regression analysis. Statistical significance was defined as p < 0.05. 642 patients met the inclusion criteria. A total of 134 patients (20.9%) received intrapartum oral labetalol, whereas 508 (79.1%) were not started on antihypertensive medications. Patients who were initiated on oral labetalol in labor for blood pressure control were significantly more likely to have a lower gestational age at delivery (35.0 vs 37.7 weeks gestation, p < 0.001) and have a higher risk of needing IV antihypertensives in labor (95.5 vs 80.6%, p < 0.001). There were no other statistically significant baseline differences between groups. 62 (46.3%) individuals in the labetalol group and 192 (37.8%) in the no antihypertensives group underwent cesarean section. In multivariable analysis of the primary outcome, patients who were started on oral labetalol in labor were not at an increased risk of cesarean (aOR 1.32, 95% CI 0.88–1.99). Composite adverse neonatal outcomes were higher in the oral labetalol group and more patients in the oral labetalol group required cesarean for worsening preeclampsia and abnormal fetal heart tones. Intrapartum oral labetalol use was not associated with a significant difference in cesarean rates. Univariable analysis suggests a higher odds of composite adverse neonatal outcomes as well as differing indications for cesarean sections, however, this is likely secondary to confounding by indication.