Objectives: Hypertension in pregnancy is one of the leading causes of maternal mortality and rapid treatment is critical. Treatment of emergent hypertensive crises in pregnancy is limited to only three medications, one of which is labetalol. Current literature recommends a daily maximum intravenous labetalol dose of 300 mg per day. However, this maximum dose has not been studied in pregnancy where higher doses may be required.

Study Design: This is a retrospective study of Obstetric patients from 12 hospitals from October 2010 to May 2018. Patients >18 years old were included and stratified into those receiving ≤ 300 mg labetalol and >300 mg in a 24-hour period.

Main Outcome Measures: Primary outcomes included maternal hypotension and bradycardia. A secondary outcome was fetal bradycardia.

Results: A total of 238 women met criteria: 208 patients in the ≤ 300mg labetalol group and 30 patients in the >300 mg labetalol group. Demographics were not different between groups except for a higher rate of cesarean delivery in the >300 mg group (63.3%). Unadjusted outcomes showed no differences between the >300 mg group and the ≤ 300 mg labetalol group in maternal hypotension (3.3% vs. 5.8%; p>0.999) but an increased rate of maternal bradycardia in the >300 mg group (30% vs. 13.5%; p=0.029). After adjusting for confounding factors there was no association seen between labetalol dose and adverse events (p=0.316). There was no difference in fetal bradycardia between the two groups (0% vs. 2.9%; p>0.999).

Conclusions: Doses of intravenous labetalol >300 mg were not associated with increased rates of maternal hypotension or bradycardia or fetal bradycardia.

Antihypertensive, Beta-blocker, Hypertension, Hypertensive emergency, Obstetrics