High blood pressure linked to birth defects

High blood pressure in early pregnancy may increase the risk of birth defects, according to new research.

The study, published in the British Medical Journal, found that high blood pressure (hypertension) alone increased the risk of a babies being born with congenital heart or neural tube defects, irrespective of whether the mother was taking drugs for hypertension.

Angiotensin-converting enzyme (ACE) inhibitors are drugs which are commonly used to treat high blood pressure, and are known to have a toxic effect on the foetus in the second and third trimester of pregnancy. However, the effect of ACE inhibitors on the foetus during the first trimester is still unclear.

This led researchers at the the Kaiser Foundation Research Institute in California to investigate whether taking ACE inhibitors in the first trimester of pregnancy also increased the risk of birth defects.

They analysed the health records of 465,754 mother and baby pairs who lived in the Northern Californian region between 1995 and 2008.

The study found that women who took ACE inhibitors in their first trimester were more likely to have a baby with some form of birth defect compared with women who did not have high blood pressure.

However, a similar increased risk was also found for women who took other drugs for hypertension and for women with high blood pressure who did not take any medication to treat it.

The findings suggest that the increased risk of birth defects was linked to high blood pressure and not the drugs used to treat it, the researchers said.

The researchers concluded: "Our finding suggests that it is likely the underlying hypertension rather than use of antihypertensive drugs in the first trimester that increases the risk of birth defects in offspring."

This article was published on Wed 19 October 2011