Relationship between blood pressure level in early pregnancy and subsequent changes in blood pressure during pregnancy

Abstract

Background. It is not known whether women with high blood pressure in the first trimester are likely to exhibit a large increase in blood pressure during pregnancy. Methods. We conducted a retrospective, longitudinal study of 1599 pregnant women, among whom 29 women (1.8%) received antihypertensive medication during pregnancy. The blood pressure levels measured during the first (7.9 ± 2.4 weeks), second (20.7 ± 1.2 weeks) and third trimesters (38.4 ± 1.7 weeks) were analyzed. The obstetric outcomes were examined in five subgroups divided according to the quintile of the first-trimester mean arterial pressure level. Results. The net change in blood pressure levels (third-trimester value minus first-trimester value) was significantly inversely correlated with the first-trimester blood pressure levels irrespective of the use or lack of use of antihypertensive drugs. Women with the highest quintile first-trimester mean arterial pressure had the largest body weight, exhibited a fall in blood pressure and had the smallest increase in body weight during pregnancy, and were significantly more likely to have a growth-restricted infant. Conclusions. Women with high initial blood pressure tended to exhibit a fall in blood pressure, whereas women with low initial blood pressure tended to exhibit a large increase in blood pressure during pregnancy. Women with high initial blood pressure and a small increase in body weight during pregnancy tended to have growth-restricted infants.