birth defects

Scientists tracked nearly 600 pregnant women in Colombia, who were reportedly infected with Zika during their third trimester. None of these women gave birth to a baby with apparent problems.

Mosquitoes infected with Zika haven't turned up along the U.S. Gulf Coast yet, but could thrive in the region's sultry summer weather. Pregnant women and their doctors are already taking precautions.

U.S. health officials say they are now convinced that Zika virus can target the developing brain before birth, leading to a severe type of microcephaly and other brain abnormalities.

A study of pregnant women in Rio de Janeiro lends credence to a suspected link between Zika and microcephaly and suggests the virus could cause other complications, including stillbirth.

U.S. disease detectives are launching a research project that health authorities hope will produce the most definitive evidence yet about whether the virus is really causing birth defects.