Babies and small children mean a huge change in lifestyle. Many things have to be cut back and a lot of time has to be dedicated to the children.

Although this may seem like a burden at the beginning of parenthood, parents are rewarded by nature. General life satisfaction is significantly higher for people with children than for those without, although satisfaction can fall during the adjustment phase for young parents, but rises after a while.
Children can infuriate their parents, especially during the defiant phase, but this is then made up for by their zest for life and affection for their parents. The beaming smile of a happy child is the best reward there is and makes parents immediately forget previous arguments.
The older the children get, the more the parents appreciate their friendship with them and feel satisfied as a result.