A team of UK researchers who looked at 34 couples have concluded that the drugs used to kickstart a woman’s ovaries during IVF treatments may disturb the genetic material of their eggs, upping the risk of Down’s syndrome in their babies, the BBC reports. The magnitude of the risk isn’t yet known, but it could also cause other conditions beyond Down’s, they say. In the study, researchers looked at 34 couples undergoing fertility treatment; all the women were older than 31 years, and were given drugs to make their ovaries release eggs for the IVF treatment. Researchers studied these eggs and found some had genetic errors, which could either cause the pregnancy to fail or a genetic disease in the child. The error often resulted in an extra copy of chromosome 21, they reported, which causes Down’s syndrome. The chance of a baby being born with a genetic condition rises with the age of the mother, especially for mothers over 35.