More than 90% of pregnant women take prescription or nonprescription (over-the-counter) drugs, or use social drugs (such as tobacco and alcohol) or illicit drugs at some time during pregnancy.
About 2-3% of all birth defects result from the use of drugs other than alcohol.
With the help of their doctors, women planning to become pregnant should take an inventory of the medications they take, researchers from Canada advise.
Dr. Anick Berard, at the University of Montreal in Quebec, noted in an email to Reuters that some medications with known fetal risk are essential during pregnancy.
According to Berard, medications such as those that treat severe acne, anxiety and psychiatric drugs, antibiotics and many drugs prescribed to treat heart disease should be avoided.
She added that many women should be aware of the side effects of any drugs they are taking — especially drugs treating a chronic condition — and plan pregnancies to avoid such drugs.
Between January 1998 and the last day of 2002, Berard and colleagues analyzed the prescriptions filled by pregnant women for drugs available at the time and known to pose fetal risks.
Their report, in BJOG: An International Journal of Obstetrics and Gynecology, shows 56 percent of 109,344 pregnant women filled at least one medication prescription. A total of 6.3 percent (6,871 women) did so for at least one medication known to pose a risk to the fetus.
They note, “These pregnancies were associated with an elevated number of (pregnancy terminations) and babies born with major (birth defects) in comparison with the expected numbers in the population.”
Specifically, terminations occurred in 47 percent of the pregnancies exposed to drugs with known fetal risks. Six percent of these pregnancies ended in miscarriage.
By contrast, in the much larger non-exposed group about 36 percent of the pregnancies had been terminated and fewer than 5 percent ended in miscarriage.
Berard’s team further identified birth defects in 8.2 percent of 2,842 infants exposed to risky drugs during gestation and available for assessment, compared with 7.1 percent of the 59,287 infants not exposed. This is “a statistically significant difference,” they note.
They emphasize, however, that it cannot be concluded that the drug exposure caused the birth defects. These pregnancies may have also been exposed to other harmful agents or maternal health conditions, they point out.
The investigators call on doctors caring for women of childbearing age to conduct a thorough medication review prior to a planned pregnancy, or as soon as an unplanned pregnancy is recognized.
For a list of drugs that can cause problems during pregnancy, visit this site: http://www.merck.com/mmhe/sec22/ch259/ch259a.html
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