A woman's blood pressure varies during pregnancy, and the pattern of the variation can provide an early clue to the potential for developing complications. This was the finding of a study of more than 400 pregnant women whose blood pressures were taken every 4 weeks via 24-hour ambulatory monitoring.

The researchers identified these patterns:

• For normotensive women, BP decreases steadily up to 20 weeks and then increases until delivery, with an average increase of 8% between the middle of gestation and delivery.
• In complicated pregnancies, BP is stable for the first 22 weeks and then increases linearly for the remainder of the pregnancy - with systolic and diastolic increases of 9% and 13%, respectively.
• Among women who developed preeclampsia, BP increased more steeply in the second half of gestation than among women who developed gestational hypertension.

For both healthy and complicated pregnancies, heart rate increases until the end of the second trimester and slightly decreases thereafter.

Related information Hypertension and Pregnancy