Alisse Hauspurg et al found that an increase in blood pressure between the first and second trimester also increased the risk of a hypertensive disorder of pregnancy like preeclampsia. This may increase the risk for stroke in the mother and for stillbirth, preterm birth, and low birth weight. The study analysed nearly 8,900 first-time mothers by comparing blood pressure readings in the first and second trimesters of pregnancy to blood pressure status in the remainder of the pregnancy. Researchers found that those having stage 1 high blood pressure (130/80 to 130/89 mmHg) was associated with an 80% the risk for preeclampsia. Even among women with normal blood pressure in the first trimester, an increase in systolic pressure (120/80 to 129/80 mmHg) was associated with a 42% higher risk of any hypertensive disorder of pregnancy, compared to women with a decrease in systolic pressure between the first and second trimester. An increase in diastolic pressure was associated with a 23% higher risk of a hypertensive disorder, compared to women who had a decrease in diastolic pressure during this time. Researchers explain that blood pressure categories with lower thresholds than those traditionally used to identify individuals as hypertensive may identify more women at risk for preeclampsia and gestational hypertension.
Source : American Journal of Obstetrics and Gynaecology 27 June, 2019 https://www.ajog.org/article/S0002-9378(19)30807-5/pdf