Chronic hypertension diagnosed before or during pregnancy and its effects on pregnancy outcomes.

Chronic hypertension (CH) during pregnancy, identified before or within the first 20 weeks, presents varying risks depending on the timing of diagnosis. This real-world study was conducted from January 2018 to June 2023 and included singleton pregnancies with CH to compare pre-pregnancy CH (Group 1) and newly diagnosed CH (Group 2). There were 565 women in the final analysis, with 307 in Group 1 with pre-pregnancy CH and 258 in Group 2 with new-onset CH. Those in Group 1 more frequently had pre-gestational diabetes and a history of hypertensive disorders in pregnancy, whereas Group 2 had a higher incidence of excessive gestational weight gain. Notably, 56.2% of Group 2 patients did not receive antihypertensive treatment before 20 weeks, while the proportion was 36.2% in Group 1, resulting in a significant difference in baseline blood pressure. The study revealed higher incidences of preterm preeclampsia (44.2% vs. 34.9%) and placental abruption (5.4% vs. 2.0%) in Group 2 compared to Group 1. After adjustment, logistic regression indicated that Group 2 had a 1.8-fold higher risk of preterm preeclampsia than Group 1. These findings suggest that pregnant women newly diagnosed with CH in the first 20 weeks face increased adverse outcomes compared to those diagnosed before pregnancy. Intense monitoring and earlier intervention may help manage women with new-onset CH.