Heartburn is a common complication in pregnancy, but researchers say pregnant women should not worry about their effects on the unborn fetus. A large study completed by Danish researchers found no connection between birth defects and the use of heartburn medications, over the counter or prescription, in the first trimester of pregnancy.

The clinical study used two types of tests to come to the reported conclusion. The first studied women from four weeks before pregnancy to three months into pregnancy. The second studied women from conception to three months into the pregnancy.

A total of 840,000 live births were included in the study of which less than 3% were born with severe birth defects. About 3.5% of the mothers taking heartburn medications gave birth to children with severe birth defects. Women who did not take heartburn medications gave birth to children with severe birth defects in 2.5% of the cases. The difference between the two groups was just 1%. The second study group that looked at women from conception, leaving out the month prior to conception, reported severe birth defects in only 3.2% of cases, narrowing the gap. After adjustments for other factors, the difference was trivial, at most.

While the study was large and the information provided helpful, there was not history taken into consideration with pregnant women included as participants. If there was an underlying condition that caused the heartburn that could have increased the chance of severe birth defects for the portion of the study population taking heartburn medications.

Source: Allen A Mitchell MD. New England Journal of Medicine. 25 November, 2010.