Drugmaker GlaxoSmithKline Plc. warned on Tuesday that there is an increased risk of cleft lip or cleft palate when the company’s antiepileptic drug Lamictal is used during early pregnancy.

The company, following discussions with Health Canada, said cleft palate deformity was detected at “an elevated rate” in infants whose mothers used the treatment during the first three months of pregnancy, compared with those who weren’t exposed to the drug.

Antiepileptic drugs have been associated with oral clefts, while other factors including smoking, heavy alcohol intake, various infections, folic acid deficiency, and vitamin A intoxication, have also contributed.

Oral clefts occur 0.5 to 2.16 times per 1,000 births.

The company advised patients who are being treated with Lamictal and who are, or intend to become pregnant, to discuss treatment with their doctors.