Pregnant women who took metformin for pregestational diabetes had a higher risk for adverse outcomes, but the risk was linked to the diabetes, not the drug, suggested researchers in a study published online in the British Journal of Clinical Pharmacology. Pregnant women on metformin for other indications, such as polycystic ovary syndrome (PCOS), had no significantly increased risk for poor outcomes. Compared with a matched reference group of pregnant women not taking metformin, those with diabetes taking metformin were approximately four times more likely to give birth to an infant with major birth defects. However, there was no significantly increased risk for pregnant women on metformin for other reasons. The adverse outcomes were tied to diabetes, not the drug.