Becoming a parent entails one of the biggest psychological transformations of one’s life. Luckily, nature gives women about forty weeks to prepare for this change. During this time both parents can make the necessary practical arrangements to prepare for the arrival of the baby. Simultaneously, they undergo a process of psychological transformation wherein they adjust to the enormous responsibility of parenting. Both mother- and father-to-be must reconfigure their identity from that of their parents’ child into their child’s parent. Furthermore, they must gird themselves for the loss of autonomy that inevitably comes with parenthood. After a child is born, a parent is no longer a single, unitary person, responsible only to himself or herself. From now on, every decision will be made from the vantage point of a responsible parent. As any parent can tell you, even when the children grow up and leave home, the sense of parental responsibility never completely goes away.

For the pregnant woman, especially, the sense of identity is drastically altered by the knowledge that another person is growing inside her. The woman’s body no longer belongs to one person, it now contains two people. Likewise, the woman’s identity expands from beyond a self-contained sense of self, to a broader, more encompassing identity that incorporates her new child. If we think of the enormous investment of time, energy, and resources that parents unthinkingly bestow on their children, we have to be impressed. Parents routinely spend inordinate sums of money, make extraordinary sacrifices and, at times, even give up their life—all for the sake of their children. In no other arena are humans so powerfully altruistic. Evolutionary biologists sum this up to the evolutionary imperative to pass on one’s genes. On the psychological level, this drive manifests in a transformation of identity; what was one becomes two. The parent sees the child not as a wholly separate person but, to some degree, as an extension of themselves.