Do blood pressure patterns differ before pregnancy hypertension develops?

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Researchers compared blood pressure changes in normotensive women, women who developed gestational hypertension or preeclampsia, and women with essential hypertension. They wanted to see how distinct the patterns were and whether rates of blood pressure change might help identify women at risk of hypertensive disorders.

They used antenatal clinic blood pressure measurements from 13,016 women in the Avon Longitudinal Study of Parents and Children who had a singleton or twin live birth surviving until at least 1 year. There was a median of 14 measurements per woman. Linear spline models described changes in systolic and diastolic blood pressure during gestational weeks 8–18, 18–30, 30–36, and 36 onward.

At the 8-week baseline, women with essential hypertension and those who went on to develop gestational hypertension or preeclampsia had higher blood pressure than normotensive women. The decrease in blood pressure until 18 weeks was smaller in gestational hypertensive pregnancies than in normotensive pregnancies. From 18 weeks onward, blood pressure rose more rapidly in gestational hypertensive and preeclamptic pregnancies than in normotensive pregnancies; in essential hypertensive pregnancies, it rose more rapidly from 30 weeks onward. From 30 weeks onward, women who developed preeclampsia had a faster rise than women who developed gestational hypertension or had essential hypertension.

The findings show distinct patterns among the groups, even from early pregnancy. These patterns may help identify women at risk of developing a hypertensive disorder later in pregnancy.