The relationship between impaired uteroplacental blood flow and blood pressure level in pregnant women with chronic and gestational hypertension

Aim. To assess the relationship between impaired uteroplacental blood flow and different levels of blood pressure in pregnant women with chronic and gestational hypertension at different stages of pregnancy with the determination of the optimal systolic blood pressure.

Methods. We conducted a prospective cohort study between 2018 and 2019. The study enrolled pregnant women aged 18 to 45 years: 55 women with chronic and gestational hypertension each, as well as 80 healthy pregnant women as control. The groups were formed by the continuous method, in which all pregnant women with arterial hypertension were included in the study until the required number of subjects was obtained. Follow-up was conducted at different gestation periods (14–16, 20–22, 28–30, 34–36 weeks) until delivery. Independent groups were compared by using the Student's t-test, the Pearson’s χ2 test, the Mann–Whitney U test, the Kruskal–Wallis H test.

Results. Comparison of the groups revealed differences in blood pressure levels at different gestation periods. In chronic hypertension compared with gestational hypertension, there was an increase in the impairment of the uteroplacental blood flow in pregnant women, indicating an unfavorable prognosis. The study of impaired uteroplacental blood flow among pregnant women with various forms of arterial hypertension revealed an increase in pregnant women with chronic arterial hypertension compared with gestational (p=0.04), indicating an unfavorable prognosis. In chronic arterial hypertension, the impairment of uteroplacental blood flow was the least for systolic pressures up to 120 mm Hg (up to 0.9%) at 14–16 and 20–22 weeks of gestation, and for 130–139 mm Hg (from 1.8 to 2.7%) in later pregnancy. In gestational hypertension, the least or no impairment rate of uteroplacental blood flow was determined for blood pressures up to 129 mm Hg at all stages of pregnancy compared with chronic hypertension.

Conclusion. The optimal systolic blood pressure in chronic hypertension reducing the risk of impaired uteroplacental blood flow in pregnant women is <129 mm Hg before 20th week of pregnancy and 130–139 mm Hg in later (20–30 weeks); in gestational hypertension, blood pressure reduction to 129 mm Hg is recommended at all stage of gestation.