Cytomegalovirus during pregnancy implicated in child hearing loss

Cytomegalovirus (CMV) contracted by a woman during pregnancy may be linked to hearing loss in her child, a new study reports.

The study evaluated 354 children 4 years and older from Washington state, all with hearing loss, who were tested for CMV at birth. Thirty-five children (9.9%) had congenital CMV, compared with 1.4% of matched controls. Those with congenital CMV had more severe hearing impairment and higher proportions of progressive and unilateral hearing loss than children who tested negative for the virus.

CMV “needs to be on the list of things we think about when we see a child with hearing loss,” says lead author Stephanie Misono, MD, MPH. The study was not designed to find out whether CMV causes hearing loss, and researchers don’t know why fetal exposure to the virus may impair hearing. Babies who contract CMV after birth are not at increased risk for hearing loss.

Women who acquire CMV during pregnancy are far more likely to pass it on to the fetus than women who become infected before pregnancy, the authors of the study observe. Nevertheless, the likelihood that the baby will develop CMV-related hearing loss is low. As many as 1 in 25 pregnant woman contract CMV. In addition to hearing loss, the virus has been linked to problems including mental retardation and cerebral palsy.

The study was published in the Archives of Otolaryngology-Head and Neck Surgery (2011;137[1]:47-53).