The U.S. Food and Drug Administration issued an alert on Friday about the risk of first-trimester miscarriages and birth defects from Novartis AG and Roche Holding AG transplant drugs.

The FDA spokesman Christopher Kelly explained that strong warning about those risks was added to the labels of Roche's CellCept and Novartis' Myfortic in November, but the new alert was meant, in part, to grab the attention of doctors who prescribe the drugs for unapproved uses such as treating lupus. The alert was issued as a reminder to doctors who prescribe the immune-suppressing drugs for the approved use of preventing rejection of transplanted organs.

According to FDA, the data from a U.S. pregnancy registry showed 15 miscarriages and four birth defects among 33 pregnancies with exposure to CellCept. The reported birth defects included cleft lip and palate, and ear deformities.

Roche spokesman Christopher Vancheri reported that the company had sent a letter to doctors when the "black box" warning, the strongest type for prescription drugs, was added last year.

Novartis spokeswoman Amy Hunter said the company had not received any reports of birth defects associated with Myfortic, known generically as mycophenolic acid, at the time of the label change in November.