Hypertension, Not Blood Pressure Drugs, Linked to Birth Defects
WEDNESDAY Oct. 19, 2011 -- Although pregnant women who have high blood pressure face a higher risk that their baby will be born with birth defects, new research indicates that the medications typically used to treat the condition will not raise that risk any further.
The finding suggests that the widely used class of high blood pressure medications known as angiotensin-converting enzyme (ACE) inhibitors are safe to use during the first trimester.
Published online Oct. 18 in the BMJ, the study results fill in a piece of the puzzle regarding the use of such medications, given that prior research had indicated that ACE inhibitors can be toxic to a fetus if used in the second and/or third trimester of pregnancy.
"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," the study authors, led by Dr. De-Kun Li of the Kaiser Foundation Research Institute in California, said in a news release from the journal.
The authors came to their conclusion after analyzing data collected between 1995 and 2008 on nearly 466,000 pairings of mothers and their children living in northern California.
The bottom line: pregnant women with high blood pressure bore a similar risk that their baby would be born with some type of birth defect whether or not they were prescribed an ACE inhibitor, another kind of high blood pressure control medication or nothing at all.
The authors noted that having high blood pressure during the first trimester did raise the birth defect risk relative to pregnant women with no high blood pressure. But their analysis pointed to the condition itself, rather than the treatment, as the primary cause for concern.
Dr. Arun Jeyabalan, an assistant professor in the division of maternal-fetal medicine in the department of obstetrics, gynecology and reproductive sciences at the University of Pittsburgh's Magee Women's Hospital, described the findings as "reassuring" yet "limited."
"The finding that there is a lack of increase in birth defects associated with [high blood pressure] medications is certainly reassuring," she noted. "But although the study is large, which is a strength, they don't have complete data on other medications that were used or on other conditions that are associated with, or may have caused, the hypertension," she added.
"So, I would say that there are some pieces of information that are missing," Jeyabalan cautioned. "And that would make me hesitate to come to the blanket conclusion they make. More research is needed, that will have more detail about the other underlying medical issues and maternal characteristics, as well as of all the medications that have been used or not used during the pregnancy."
For more on pregnancy and high blood pressure, visit the March of Dimes.
Posted: October 2011
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