Why does childbirth hurt?

What if pain in childbirth is an unnecessary remnant from human evolution?

Natural childbirth advocates often claim that the pain of childbirth brings a variety of benefits. Indeed, there are some who claim that the pain triggers a hormone cascade that is necessary for maternal infant bonding. Others insist that childbirth is not painful and is actually “ecstatic” and provides sexual pleasure. These varying theories hinge on the notion that the pain of childbirth adds something of value to the experience birth, and that the pain is good and beneficial. However, evidence derived from the study of ancient childbirth suggests that natural childbirth advocates have it precisely backwards. The pain of childbirth is not needed to trigger good things, it is vital to prevent maternal and neonatal death, and is a vestigial response that is no longer needed.

Before we consider ancient childbirth, it makes sense to think about the role of pain in the human body. Pain is almost always a sign that something is wrong, perhaps seriously wrong. Indeed, pain is so important to human survival that it can stimulate reflexive reactions. Put your hand on a hot object and you will actually begin pulling it away before you consciously feel the pain. That’s because there are nerve circuits in the spinal cord that allow you to unconsciously perceive the pain and pull away, skipping the step of consciously noticing the pain so as to save time and limit damage.

When you think about it, there is no instance in which pain is not designed to protect against damage. At the level of the skin, pain tells us what is safe to touch and what is dangerous. At the level of bone, the pain of a broken bone is so great that it forces immobility, and that probably helps the bone to heal properly. The pain of disease makes people search for ways to diminish the pain, and perhaps improve survival from the specific problem. So, at the most basic level, there is no reason to believe that the pain of labor is beneficial in and of itself. Unless labor pain is different from all other types of pain of human existence, labor pain exists to warn.

Human childbirth has existed in its present form for millions of years. During that time, the death rate of both mothers and infants was extraordinarily high. Evolution would certainly have favored strategies that lowered the risk of death. Perhaps labor pain, like all other forms of human pain, existed to warn women to seek assistance.

Seeking assistance in childbirth may have lowered infant mortality by having help in situations like breech birth (which usually cannot be accomplished without some manipulation of the baby’s body) and may have lowered the death rate from postpartum hemorrhage, because the assistant could massage a woman’s uterus after birth. Assistance in childbirth must be very important from an evolutionary perspective because anthrologists report that all human societies have birth attendants.

According to Karen Rosenberg (a paleoanthropologist who studies human birth) and Wenda Trevathan (a biological anthropologist and trained midwife) writing in Scientific American special edition, New Look At Human Evolution, 2003:

… [W]e suggest that natural selection long ago favored the behavior of seeking assistance during birth because such help compensated for these difficulties. Mothers probably did not seek assistance solely because they predicted the risk that childbirth poses, however. Pain, fear and anxiety more likely drove their desire for companionship and security.

Psychiatrists have argued that natural selection might have favored such emotions—also common during illness and injury—because they led individuals who experienced them to seek the protection of companions, which would have given them a better chance of surviving. The offspring of the survivors would then also have an enhanced tendency to experience such emotions during times of pain or disease. Taking into consideration the evolutionary advantage that fear and anxiety impart, it is no surprise that women commonly experience these emotions during labor and delivery.

It would be quite ironic for natural childbirth advocacy if the role of pain in labor was to alert women to the inherently dangerous nature of childbirth, so they would seek assistance. It would also mean that labor pain has outlived its usefulness. Far from being beneficial, labor pain may turn out to have only harmful effects.