Q: My baby has undescended testicles. Is this common?

A: Undescended testicles are increasingly common, affecting around one in 100 full term baby boys and one in 10 premature male infants. Usually, only one testicle fails to come down, but occasionally both testicles remain inside the abdomen. An undescended testicle may creep down on its own during the first few months of life, but if it is not down by the age 12 months, an operation is essential to correct the problem. This is because if a testicle is left inside the body it will fail to develop properly and will produce very few sperm at puberty. Those left inside are also more likely to become cancerous in the future.