The typical gestation period is five to six months. When they are about to give birth, sows temporarily leave their families to farrow in a separate hole. The litter is 2–8 piglets, with 2–4 typical. The sow will stay in the hole for several weeks, nursing her piglets. Common warthog sows have been observed to nurse foster piglets if they lose their own litter. This behavior, known as allosucking, makes them cooperative breeders. Allosucking does not seem to be a case of mistaken identity or milk theft, and may be a sign of kin altruism. Piglets begin grazing at about two to three weeks and are weaned by six months. Piglets quickly attain mobility and stay close to their mothers for defense.