Hemangiomas are pretty common among newborns. Girls develop hemangiomas more often than boys do, as do twins, babies with light skin and premature babies with a low birth weight [sources: Children's Hospital Boston, Mayo Clinic]. But what causes hemangiomas to show up in the first place?
It turns out that researchers still aren't quite sure. Hemangiomas are one of those medical mysteries for which doctors haven't been able to determine a conclusive cause. No one has proven that hemangiomas are inherited genetically, but 10 percent of babies do have family members with vascular birthmarks [source: Children's Hospital Boston].
Even though there still isn't a definitive cause, there are a few things that can be ruled out. For example, when a baby develops a hemangioma, many new mothers probably wonder what they might have wrong while pregnant, but the answer to that question is nothing [source: Children's Hospital Boston]. No conclusive research has shown how a mother's actions during pregnancy affect whether her child is born with a hemangioma. There aren't any foods that have been shown to cause hemangiomas, and the same can also be said for medications taken during pregnancy [source: Cincinnati Children's].
There may be one situation beyond a mother's control that could have something to do with the formation of hemangiomas. Some studies have linked these growths to proteins or cells that move from the placenta to the baby [sources: Mayo Clinic, Hochman]. More extensive research still needs to be done before any conclusions are made, though.
Since doctors don't know exactly what causes hemangiomas, they're impossible to prevent and can be hard to treat. Most hemangiomas won't need treatment because they will go away on their own, but some will need medical attention. Even if a hemangioma doesn't require it, some doctors may recommend treatment for cosmetic purposes: The growths can become unsightly and might affect a child's psychological development. In addition, some parents may worry that their child is physically hurting as a result of the hemangioma.
Keep reading to find out whether hemangiomas are painful for babies.