Zika-caused birth defect may become clear only after birth

NEW YORK (AP) — Researchers say a severe birth defect caused by Zika infection may not be apparent at birth but develop months afterward, further confirmation that the virus can cause unseen damage to developing babies.

Most people infected with Zika never develop symptoms, but infection during pregnancy can cause devastating birth defects, including microcephaly, in which a baby's skull is much smaller than expected because the brain hasn't developed properly.

The study confirms that the absence of microcephaly at birth doesn't mean there are no abnormalities in the children of Zika-infected mothers, CDC officials said.

[...] it is likely to further worry potentially infected parents who may grow alarmed by signs that their newborn's head is a little small, said Dr. Thierry Huisman, a Johns Hopkins University professor of radiology who has studied Zika-affected children.

Investigators are working to determine what proportion of Zika-infected women have babies with birth defects, and how the risk varies based on when during the pregnancy the infection occurred.