A: Miles, approximately 2 to 5 percent of boys are born with undescended testicles, including up to 30 percent of premature baby boys. During the development of the fetus, the boy's testes develop in the fetus' abdomen. Near the end of the pregnancy, the testes usually descend through the fetus' inguinal canal into the scrotum. Sometimes one or both testes don't descend properly and can't be felt in the baby's scrotum at birth. An exam and/or ultrasound may find the undescended testis in the baby's inguinal canal or abdomen.

In most babies born with an undescended testicle, the testicle will naturally descend into the scrotum within the first three to six months of life. If this hasn't happened by 6 months of age, surgery might be necessary to bring the testis into the scrotum. Sometimes hormone treatments are tried before surgery, but this only works to help the testicle descend in a small proportion of cases. It's recommended that the surgery be done by 1 year of age since, over time, the testes can become damaged, possibly leading to infertility and testicular cancer. The surgery is usually performed on an outpatient basis.

Be sure to have close follow-up with your baby's doctor over the next three to six months.