Rattlesnakes do not lay eggs and instead give birth to live young. They are ovoviviparous, meaning that the eggs of the rattlesnake hatch internally before being birthed. A pregnant rattlesnake may have between four and 25 eggs.
Rattlesnakes reach sexual maturity at approximately 3 years of age. Mating season is generally in the spring and following hibernation, but fall-time courtship happens occasionally. Most juvenile rattlesnakes are born between August and October. At birth, rattlesnakes are about 10 inches long and are entirely self-sufficient. The rattle on newborns is not yet developed, although juveniles are capable of quick strikes when defending themselves. While independent from birth, most rattlesnakes do not survive their first year of life due to starvation, being eaten or inadequate shelter.