High BP before pregnancy may raise miscarriage risk

High blood pressure before conception and early in pregnancy may increase the risk of pregnancy loss, even if the woman does not have a hypertension diagnosis, new research has found.

"Elevated blood pressure among young adults is associated with a higher risk of heart disease later in life, and this study suggests it may also have an effect on reproductive health," said lead author of the study Carrie Nobles from Eunice Kennedy Shriver National Institute for Child Health and Human Development (NICHD) in Maryland, US.

Millimeter of mercury, or mm Hg, is the unit of measure used for blood pressure.The findings, published in the journal Hypertension, showed that for every 10 mm Hg increase in diastolic blood pressure (pressure when the heart is resting between beats), there was 18 per cent higher risk for pregnancy loss among the study population.

The researchers also found a 17 per cent increase in pregnancy loss for every 10 mm Hg increase in mean arterial pressure, a measure of the average pressure in the arteries during full heart beat cycles. 

The researcher studied more than 1,200 women who had already experienced one or two pregnancy losses and were trying to become pregnant. The findings were similar for preconception and early-pregnancy blood pressure.

"The impact of cardiovascular risk factors starts really early in life. Physicians treating women of reproductive age should pay attention to slightly elevated blood pressure because it may have other not-well-recognised effects, such as adverse pregnancy outcome," said senior author of the study Enrique Schisterman from NICHD. 

"Preconception is a previously unrecognized critical window for intervention such as lifestyle changes that can help prevent later heart disease and may also improve reproductive health," Schisterman said.