A large study in Denmark suggests that a prescription drug for yeast infections may increase chances for miscarriages when used early in pregnancy.

The research involved oral versions of fluconazole (floo-KON'-na-zole). The study doesn't provide any proof of harm, although the drug has been linked with other problems when used in high doses in pregnancy.

The researchers looked at more than 1 million pregnancies. Women who used the drug during the first six months of pregnancy were almost 50 percent more likely than nonusers to have a miscarriage.

While fewer than 10 percent of women in each group had miscarriages, the researchers said doctors should use caution in prescribing the drug early in pregnancy.

The study was published Tuesday in the Journal of the American Medical Association.