Hippos mate in water and there is no fixed breeding season. The gestation period of females is 210-255 days. They give birth in water and give birth to 1 litter per litter. Newborn cubs weigh 40-50 kg and can walk and dive 5 minutes after birth. The hippopotamus mother with a baby has a very ferocious temperament. After the baby beast is born, the female beast will take care of it carefully, breastfeeding in the water, and only let them move within the visible range, and patiently teach them to dive and roll. Protect them from harm. For the next few months, the female animal often took her cubs to live away from the group, because the cubs may be killed by the ferocious males or attacked by crocodiles. After 4-6 months, the cubs will be able to eat grass. The lactation period is about 1 year. The raising period of the offspring that a female usually bears alone can be extended to 18 months. Females mature between 7-9 years old, males are between 9-11 years old, and their life span is about 30-40 years.
Female hippos usually live alone with a baby hippopotamus for two months, enjoying the happiness of family in peace. The mother and son often lie down and rest quietly, and the little hippopotamus snuggles close to the mother's mouth. Sometimes, the mother wants to take it into the water again, because the hippopotamus can't get rid of the problem of how to stabilize its body temperature. After staying on the bank for a long time, it has to go into the water to cool down. At this time, the baby hippopotamus will skilfully climb onto the mother's back or neck and enter . The baby hippopotamus still needs to feed constantly. The female hippo lies on her back and stretches out one hind leg, and her breast is exposed. When the little river is feeding, the female hippo will use the other hind leg to support her breast. Massage on the ground to stimulate milk. Mosquitoes will fly from time to time. These guys like the stray milk and sometimes rest around the nipple. So the female hippo slaps the river with her big mouth to scare away the mosquitoes flying around. The baby hippo can go ashore by herself, and the female hippopotamus no longer spoils it and lets it dive by herself. The baby hippo will inevitably fall when climbing ashore. The female hippopotamus uses her mouth to support her and encourage her to get up. The female hippopotamus also does not condone the naughty game of the baby hippopotamus, and will block it with a huge body, or simply use her big mouth to "learn" it.