In extremely rare instances, newborns can contract cancer from their pregnant moms during delivery, a case report published in the New England Journal of Medicine suggests. Two boys —a 23-month-old and a 6-year-old—developed lung cancers that were exact genetic matches to cervical cancers within their mothers at the time of birth. “In our cases, we think that tumors arose from mother-to-infant vaginal transmission through aspiration of tumorcontaminated vaginal fluids during birth,” said lead researcher Dr. Ayumu Arakawa, a pediatric oncologist with the National Cancer Center Hospital in Tokyo, Japan. In both cases, doctors used genetic testing to positively link the mothers’ cervical cancers to the lung cancers in their sons. The study authors suggest that pregnant women with cervical cancers consider having a C-section, to avoid the risk of passing cancer to their newborn.