When does testicles start to descend on a baby boy?

Testicle development: If the testes are not in the scrotum at the time of birth, they should descend by 1 year of age. If they have not done so, consult a pediatric urologist. Additionally, if neither testis can be felt in the scrotum, then I would see a pedi urologist now.

32 wks gestation: The testis begin their descent at the upper inguinal canal about 28 wks and descend into the scrotum about 34 wks. A fraction of normal kids have delayed descent and may remain in the canal, but should descend in the first months after birth.If not in the sac at birth they should be monitored closely. Exploration, retrieval and movement into proper location by a year is the recommended treatment.