Almost a year has passed since Brazilian health officials announced they had established a link between the mosquito-borne virus Zika and birth defects. Since the beginning of the outbreak of the Zika virus in 2015 in Brazil and other Latin American countries, researchers have raised increasing alarm over the disease’s link to birth defects. The most severe of these defects is microcephaly, a condition in which children are born with head circumferences well below normal, with effects ranging from mild developmental delay to devastating cognitive and neurological impairment. While the exact mechanism by which Zika causes microcephaly in infants in utero is not yet known, a growing body of evidence supports the link between the virus and the defect. According to a recent published review of evidence to date, “data from Brazil regarding the temporal and geographic association between Zika virus infection and the later appearance of infants with congenital microcephaly are compelling.” Given the severity of many microcephaly cases, governments and health organizations have raced to gather and distribute information that will help women facing the virus.