Ulcer Drug Linked To Birth Defects

TORONTO, Ontario, Canada--Researchers at Toronto's Hospital for Sick Children (HSC) and several hospitals in Brazil have determined that a drug commonly used for the treatment and prevention of ulcers causes a significant birth defect if taken during pregnancy. The drug, misoprostol, joins an international list of approximately 24 medications proven to cause birth defects. The research is reported in the June 25 issue of the New England Journal of Medicine.

"Our research determined that misoprostol causes a congenital facial paralysis known as Mobius syndrome," explains lead researcher Anne Pastuszak, MSc, of HSC's Motherisk program and director of the University of Toronto Fetal Diagnosis and Treatment Centre. "The drug is not recommended for use in pregnancy because it may stimulate uterine contractions and cause vaginal bleeding and miscarriage."

It is these side effects that prompt some Brazilian women to take misoprostol--which is available over the counter in Brazil but only by prescription in Canada--in an attempt to terminate their pregnancy. However, the drug does not always cause miscarriage and children born to mothers who have taken misoprostol are more likely to have Mobius syndrome than women who have not taken the drug.

The case control study compared the frequency of misoprostol use during the first trimester between mothers of 96 Brazilian infants diagnosed with Mobius syndrome and mothers of 96 infants with neural tube defects. Among the mothers of infants with Mobius syndrome, 47 (49 per cent) had taken misoprostol during pregnancy compared with just three (three percent) of the mothers from the other group.

Mobius syndrome is a rare disorder that is characterized by lifetime facial paralysis. People with Mobius syndrome can't smile or frown, and they often can't blink or move their eyes from side to side. Mobius syndrome results from the under-development of two important cranial nerves, however, the precise cause is unknown.

This research was funded by The Hospital for Sick Children Foundation and the Brazilian Research Council.