Hypertension In Early Pregnancy Raises Birth Defect Risk

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Academic Journal
Main Category: Pregnancy / Obstetrics
Also Included In: Hypertension;  Pediatrics / Children's Health
Article Date: 18 Oct 2011 - 20:00 PDT


A new study suggests that hypertension early on during pregnancy increases the risk of giving birth to babies with birth defects, researchers from the Kaiser Foundation Research Institute in California reported in the BMJ (British Medical Journal). The authors added that the raised risk is there, regardless of whether they were prescribed hypertensive drugs, suggesting that it is the underlying hypertension, rather than the medication that raises the risk.

Commonly prescribed drugs for hypertension contain Angiotensin-converting enzyme (ACE) inhibitors which are known to have a toxic effect on fetuses during the second or third trimesters of pregnancy, however, little is known about their effects on a fetus during the first trimester of pregnancy.

Research leader Dr De-Kun Li of the Kaiser Foundation Research Institute in California and team set out to whether using ACE inhibitors during a woman's first trimester is linked to birth defects.

For their study researchers evaluated data on 465,754 mothers and their infants from the Kaiser Permanente Northern Californian region. The study period comprised data between 1995 and 2008 and contained information on any prescribed and dispensed medication.

The findings revealed that women using ACE inhibitors during their first pregnancy trimester had a potentially higher risk of having a baby with some form of birth defect compared with women without hypertension or those who were not taking any form of antihypertensive medication.

The researchers also discovered a comparable higher risk amongst women using other hypertensive drugs and those who suffered from hypertension but who did not take any antihypertensive drugs.

In a concluding statement the authors say:

"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."

Based on the available studies, professor Allen Mitchell from Boston University comments in an accompanying editorial that it would seem acceptable to suggest that first-trimester exposure to ACE inhibitors poses no greater risk of birth defects than other antihiypertensives, and that it is the underlying hypertension that places the fetus at risk.

Mitchell suggests that although clinicians have to identify and control hypertension, particularly in pregnant women, "we have much to learn about how hypertension can cause birth defects."

Written by Petra Rattue

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