Birthmarks have always been something of a mystery. Scientists know that a hemangioma is a benign tumor of cells that line blood vessels, appearing during the first few weeks of life as a large birthmark or lesion, but not much more. Now a study published in Pediatric Dermatology answers some remaining questions and reveals that a disturbance of oxygen depletion was found in placentas of babies who developed infantile hemangioma (IH).

Researchers reviewed placental samples from 26 pregnancies with babies who weighed less than 3.5 pounds, 13 consisting of newborns who developed IH after birth and 13 healthy preterm infants who did not have IH.

Only one of the infants without IH showed an abnormal placenta. The higher ratio of placental anomalies in babies with IH suggests that reduced oxygen to the placenta contributed to fetal stress, and that stress led to infantile hemangioma development.

“Our results suggest that disturbed placental circulation is a factor underlying the development of hemangiomas in very low weight newborns and indicates that placental examination is essential for clarifying the physiologic changes leading to IH in babies with normal birth weight,” the authors conclude.