Time in therapeutic range and risk of preeclampsia in chronic hypertensive pregnant women

Pregnancy Hypertensive Disorders (PHD), particularly Preeclampsia (PE), are significant contributors to maternal-fetal morbidity and mortality, with chronic arterial hypertension (CH) being a major risk factor. The prevalence of CH has risen alongside obesity and advanced maternal age. While antihypertensive treatment mitigates adverse pregnancy outcomes, the duration of effective blood pressure (BP) control, termed Time in Therapeutic Range (TTR), has not been extensively studied in pregnant women. TTR, reflecting the proportion of time BP remains within target ranges, predicts long-term cardiovascular and renal events in the general population but remains unexplored in pregnancy. This study investigates the association between TTR, assessed through office BP (OBP) and ambulatory BP monitoring (ABPM), and PE development in pregnant women with CH. In a retrospective longitudinal study, data from 166 pregnant women with HA referred to our hospital analyzed. BP was measured using OBP and ABPM from 10 weeks of gestation, with TTR calculated as the percentage of visits where BP remained within target ranges. The study defined four TTR control groups: 0%, 33%, 50–66%, and 100%. Results showed that 28% of the participants developed PE, with a higher incidence correlating with lower TTR in ABPM. TTR in ABPM was a significant predictor of PE risk, with the best-controlled group (100% TTR) demonstrating a 92% reduced risk compared to those with 0% TTR. The agreement between OBP and ABPM TTR was low, emphasizing the importance of ABPM for accurate BP monitoring in pregnancy. This study indicates that integrating ABPM for TTR assessment in high-risk pregnancies has the potential to reduce maternal and fetal complications.