A new research study published in the British Medical Journal, claims women with high blood pressure during pregnancy are more likely to have children with birth defects. The study takes into consideration medications prescribed to lower blood pressure and states the birth defects are not associated with these medications. The most critical time is early pregnancy.

Other research studies have noted the connection between high blood pressure and birth defects, but the connection was thought to have something to do with medications not high blood pressure itself. This study took hypertension medications about of the picture thus connecting the condition with the resulting birth defects.

At the heart of the study were ACE drugs. ACE stands for angiotensin-converting enzyme. Drugs to inhibit ACE are prescribed during pregnancy to treat hypertension. The study investigated more than 460,000 women and infants in California between 1995 and 2008. Pregnant women using ACE inhibitors to treat hypertension were more likely to have infants with birth defects, but there was another connection that sparked the interest of researchers.

Women who took other hypertension medications were compared with women who took no medications. The incidence of birth defects between these two groups was extremely similar; leading researchers to believe hypertension caused the birth defects and not the medications used to treat the condition.

According to researchers, “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.” Researchers and independent doctors agree that hypertension must be controlled during pregnancy, but the increased risk of birth defects needs to be taken into consideration when treatment plans are developed. Early detection and treatment of hypertension before pregnancy could decrease the risk of birth defects, but further study is needed to learn how hypertension affects the fetus compared to anti-hypertension drugs.

The study did not address preeclampsia, though preeclampsia does cause hypertension later in pregnancy.

Source: D.-K. Li, C. Yang, S. Andrade, V. Tavares, J. R. Ferber. British Medical Journal (BMJ). 18 October, 2011.