Most of the time, a boy’s testicles descend by the time he is 9 months old. Undescended testicles are fairly common in infants who are born early. The problem occurs less often in full-term infants.
Some babies have a condition called retractile testes and the health care provider may not be able find the testicles. In this case, the testicle is normal but is pulled back out of the scrotum by a muscle reflex. This is able to occur because the testicles are still small before puberty. The testicles will descend normally at puberty and surgery is not needed.
Testicles that do not naturally descend into the scrotum are considered abnormal. An undescended testicle is more likely to develop cancer, even if it is brought into the scrotum with surgery. Cancer is also more likely in the other testicle.
Bringing the testicle into the scrotum can improve sperm production and increase the chances of good fertility. It also allows the health care provider to do an exam for the early detection of cancer.
In other cases, no testicle may be found, even during surgery. This may be due to a problem that occurred while the baby was still developing before birth.