Background: The pathogenesis of essential hypertension (EH) is a complex multifactorial process. Little is known about the association between pregnancy and blood pressure fluctuation in women with EH. In this study we wanted to evaluate the relationship between the blood pressure (BP) and plasma renin activity (PRA) as well as serum and urine aldosterone (ALDO) levels in pregnant women with essential hypertension.
Materials and methods: We analyzed 84 pregnant women (97% primigravida) with EH aged 22-40 (mean 29.5 +/- 5.4) years and 60 healthy pregnant women aged 22-40 (mean 28.5 +/- 4.9) years. In women with EH, antihypertensive therapy was stopped immediately after pregnancy was confirmed. Patients with EH were divided to two groups: 1) with BP > or = 140/90 and 2) with BP > or = 140/90. PRA and ALDO as well as sodium and potassium excretion were measured three times in different periods of pregnancy: 8-12 weeks, 24-28 weeks, 34-38 weeks. In addition, both PRA and ALDO were analyzed in 4th month after delivery i.e. in the time, in which woman is reached hormonal and hemodynamic stability. PRA and ALDO were determined by RIA methods. BP was monitored by standardized method using mercury manometer.
Results: PRA and ALDO concentrations in both: serum and urine were increased during pregnancy in all studied groups. No difference in kinetics of PRA and ALDO was stated between healthy pregnant women with EH. Increased was observed in women and during pregnancy. Statistically significant, the highest level of PRA was noted in fourth month after delivery in women with BP > 140/90. In this period, however, concentrations of ALDO in both serum and urine were the same in all examined women.
Conclusion: 1. In women with EH and BP < 160/100 mm Hg during pregnancy PRA and concentration of ALDO in serum as well as ALDO excretion were the same as in healthy pregnancy women. 2. Reduction of blood pressure was observed in the group of women with the lowest PRA in fourth month after delivery. 3. PRA measured in women with EH may be a predictive parameter of BP during pregnancy.