This is an example of a sacrococcygeal teratoma [sa-crow-cock-sa-jeal tear-a-toma], which is a tumor that affects roughly one out of every 35,000 births. The tumor is composed of "germ cells" which are supposed to become part of the reproductive system, but in this case have become tumorous. Such large teratomas are largely a danger during delivery, or from the blood system of the tumor monopolizing too much of the baby's circulatory system. Often surgeons will remove the tumor while the baby is still in the womb, or deliver the baby by caesarian and operate afterwards.