Letrozole, a drug sometimes prescribed to help a woman become pregnant, may cause birth defects and miscarriages, Canadian health regulators have warned. (Photo: yahoo)

BEIJING, Nov. 30 -- Letrozole, a drug sometimes prescribed to help a woman become pregnant, may cause birth defects and miscarriages, Canadian health regulators have warned.

    The warning came after a Canadian study which shows ;babies of mothers who got pregnant after taking the drug had nearly triple the risk of fetal abnormalities, compared with those who did not take the drug.

    In the study, Canadian researchers analyzed 150 births that came after treatment with the Letrozole.

    "We found seven serious malformations in 150 cases, which is about 4.7%," said Dr. Biljan. M.D., director of the Montreal Fertility Center.

    Letrozole, marketed under the brand name Femara, is approved for use only in postmenopausal women with breast cancer. But U.S. and Canadian doctors often prescribe it to prompt ovulation as part of fertility treatments.

    Health Canada, the country's health care agency, issued the warning jointly with the drug's manufacturer Novartis about unapproved off-label use of the drug to fertility specialists, gynecologists and obstetricians.

    "Femara (letrozole) is contraindicated in women with premenopausal endocrine status, in pregnancy, and/or lactation due to the potential for maternal and fetal toxicity and fetal malformations," said the warning, posted on Health Canada's website.

    Novartis has received 13 adverse reaction reports worldwide involving women exposed to Femara during pregnancy. Of those, four involved harm to the baby, said Jirina Vlk, a Health Canada spokeswoman.

   (Agencies)