A study in nearly 70,000 pregnant women has found no link between migraine drugs called triptans and the risk of birth defects.

Triptans are among the most powerful drugs used for migraine; others include aspirin, Excedrin, and ibuprofen.

The study, conducted by Katerina Nezvalova-Henriksen of the University of Oslo in Norway, noted that while as many as three in 10 women may develop migraines during their childbearing years, women often shy away from using such drugs during pregnancy because of safety concerns.

The study found that the percentage of birth defects was the same for those who took triptans during pregnancy as those who were not migraine sufferers: 5 percent.

The authors of the study noted, "While it is important to exert caution when using any medications during pregnancy, this study indicates that pregnant women can either start or continue taking triptans without "any major risk" of miscarriage, premature delivery, or other bad outcomes".

However, the researchers did find that women who used triptans in their second or third trimester were more likely to develop a condition called atonic uterus, in which the uterus fails to contract back to its normal size after delivery. They were also more likely to lose significant amounts of blood during labor and delivery.

Many women who suffer from migraines will experience improvements in their symptoms after their first trimester, Nezvalova-Henriksen and her team note, yet those whose symptoms don’t improve by then aren’t likely to get better.

"Although the findings are reassuring, confirmation in independent studies is warranted, "the researchers conclude.