Women considering fertility treatments should know that there might be a risk of birth defects. Infants born as a result of assistant reproductive technology, also known as ART (in vitro fertilization and the use of donor eggs) are two to four times more likely to have certain types of birth defects than children conceived naturally, a new study from the Centers for Disease Control and Prevention has found. These defects range from heart anomalies, cleft lips to gastrointestinal defects.

Jennita Reefhuis, Ph.D., an epidemiologist at the CDC's National Center on Birth Defects and Developmental Disabilities, and her colleagues compared 281 births using ART with more than 14,000 naturally conceived births. The research found that there was twice the risk of heart defect, more than twice the risk of cleft lip and more than four times the risk of gastrointestinal defects.

The study is published in the journal Human Reproduction. The study did not include women who only took fertility drugs and did not have procedures performed.

“I think it is important for couples to consider the fact that there may be a risk for birth defects,” said Jennita Reefhuis, an epidemiologist at the CDc and the first author of the study.

Another idea to keep in mind is that twins and other multiple births have a higher risk of birth defects than single births. The risk of a birth defect remains low, the researchers noted. For example, the risk of a baby being born with a cleft lip is about 1 in 950 when conceived naturally. A baby conceived via fertility treatment would be at a rate of 1 in every 425 births.

The study was small and the researchers said that more research was needed to test the findings.

Currently, about 12 percent of women ages 15 to 44 in the United States seek infertility treatments, according to a 2002 national survey.