They make male hormones and sperm. Usually both testicles are inside the scrotum. While boy babies are still growing inside the uterus, their testicles are inside their abdomen. They usually move down into the scrotum just before or just after birth. An undescended testicle is one that did not move down into the scrotum.
Undescended testicles are common in boy babies.
Up to 30 percent of boys born early and 5 percent of boys born on time have at least one undescended testicle. If your newborn baby has an undescended testicle, it will usually move down on its own in the first few months of life. If this doesn't happen after 3 or 4 months, it may need to be treated by a doctor. Your doctor can tell if your baby has an undescended testicle by checking the baby's scrotum. A nonpalpable testicle might be inside the abdomen, or it might be too small to feel or not there at all.