Chronic hypertension in pregnancy: insights into adverse outcomes prevention

Objectives: The aim of this study was to investigate the role of low molecular weight heparin in the prevention of preeclampsia and/or fetal growth restriction in pregnant women with chronic hypertension. Methods: Women diagnosed with chronic hypertension were retrospectively selected from our electronic database from January 2019 to January 2024. The primary endpoint was the occurrence of adverse pregnancy outcomes described as the onset of preeclampsia and/or fetal growth restriction. Results: A total of 219 pregnant women with chronic hypertension were included. BMI before pregnancy was 27.8 ± 6.4 kg/m2 and age 36.1 ± 5.4 years. Preeclampsia and fetal growth restriction occurred in 22.9 and 9.6% of patients, respectively. As concerns prophylaxis in the first trimester, 80.1% of patients were administered low-dose aspirin (100 mg), while 16.7% low molecular weight heparin (at prophylactic doses according to BMI), of which 86.1% aspirin + heparin. The rate of preeclampsia was similar in patients taking aspirin or not (21.3 vs. 25%), while it significantly differed in those administered with heparin as thromboprophylaxis (8.8 vs. 25%, P = 0.04). Fetal growth restriction occurrence did not differ according to the use of prophylaxis. High resistance at uterine arteries Doppler velocimetry at 24-25 weeks of gestation was confirmed to be associated with the onset of preeclampsia (51 vs. 11.9%; P < 0.001) and fetal growth restriction (18.2 vs. 6.9%; P = 0.04). Conclusion: Thromboprophylaxis with low molecular weight heparin reduces the onset of superimposed preeclampsia, independently from aspirin intake.