zika virus Researchers homing in on risk of birth defects

Associated Press

NEW YORK

As the international epidemic of Zika virus disease has unfolded and led to devastating birth defects for at least 1,300 children in eight countries, an agonizing question has persisted: What is the chance that an infected pregnant woman will have a baby with these defects?

Researchers don’t yet have a complete answer, but they are slowly homing in on one.

The largest study to look at the question says the risk of one especially severe type of birth defect is “substantial” – in the range of 1 percent to 14 percent. It also reinforces the understanding that women infected in early pregnancy face the greatest risk.

The range is so unusually wide because researchers are relying on imprecise and incomplete information as they to try to quickly estimate the level of risk in advance of what they say is likely transmission of Zika by mosquitoes in the U.S. later this year.

The study focused on what was seen in just one place, a state in northeast Brazil. And it looks only at microcephaly, a condition in which a baby’s skull is much smaller than expected because the brain hasn’t developed properly. But health officials say Zika can cause other birth defects, too.