Why is human childbirth so painful?

The article discusses why most human mothers have to experience pain during childbirth. Virtually all human mothers experience pain in childbirth, and delivery takes much longer than in other mammals. Human newborns are unique among mammals in that human babies cannot immediately get up, feed, and walk around like a newborn foal. What mothers doe for their babies is to meet their enormous metabolic needs, enabling baby brains to grow big before and immediately after birth. The prolonged period of breastfeeding needed by a human baby is the most energetically demanding period of a female's life. A mother may even allocate her brain during pregnancy, losing some four percent of its volume, to meet the energy demands of her baby's brain. As the baby grows in both brain and body in the womb, its demand for energy accelerates exponentially.