Effects of Early vs. Late Administration of Labetalol on Maternal Cerebral Perfusion and Fetal Growth in Severe Pre-eclampsia

Fangfang Yu^*Jiahui Wang

• The First Affiliated Hospital of Soochow University, Suzhou, China

Background: Severe pre-eclampsia is a major contributor to maternal and perinatal morbidity and mortality worldwide. Antihypertensive therapy is essential, yet the impact of the timing of intravenous labetalol initiation on maternal cerebral hemodynamics and clinical outcomes remains uncertain, particularly in Chinese populations. Methods: In this retrospective cohort study, we evaluated women with severe pre-eclampsia treated at the Department of Obstetrics and Gynecology, The First Affiliated Hospital of Soochow University, Jiangsu Province, China, between March 2023 and July 2025. Women diagnosed with severe pre-eclampsia were categorized into two groups based on the timing of labetalol administration: early (≤60 minutes after diagnosis) and late (>60 minutes). Clinical characteristics, laboratory data, treatment details, and outcomes were retrieved from electronic records. Primary outcomes were changes in middle cerebral artery pulsatility index (MCA PI) and time to blood pressure control. Secondary outcomes included maternal complications (HELLP syndrome, acute kidney injury, pulmonary edema, intensive care unit admission, maternal death) and neonatal outcomes (birthweight, small-for-gestational-age, NICU admission, neonatal complications, perinatal death). Statistical analyses employed Welch's t test, Mann–Whitney U test, χ² or Fisher's exact test, and correlation testing, with p < 0.05 considered significant. Results: Of 372 women screened, 320 were included (162 early-treatment, 158 late-treatment). Baseline demographic and laboratory profiles were comparable. Early labetalol initiation was associated with significantly greater increases in MCA PI at 60 minutes, 6 hours, and 24 hours (p ≤ 0.040) and with shorter median time to blood pressure control (60 vs. 95 minutes, p < 0.001). At 6 and 24 hours, systolic and diastolic pressures were lower in the early group (p < 0.01). Improvement in MCA PI was inversely correlated with time to blood pressure control, suggesting faster hemodynamic stabilization with earlier treatment. Maternal complications and neonatal outcomes did not differ significantly between groups. Conclusions: Early initiation of intravenous labetalol was associated with improved maternal cerebral perfusion and more rapid blood pressure stabilization, without an increase in adverse maternal or neonatal outcomes. These findings highlight the importance of timely antihypertensive therapy in severe pre-eclampsia, although prospective studies are required to establish causality and long-term clinical benefit.