Abstract
Some women choose not to reproduce. This is counterintuitive from an evolutionary theoretical perspective as individual reproductive success requires one or more offspring. The main issue is why individual women might choose not to reproduce and whether the choice is necessarily maladaptive. This study proposes that the choice to not reproduce can be adaptive. Females who choose to not reproduce may be reacting to a fitness cost warning of heritable diseases or medical conditions that could affect the individual costs of reproduction. The body is known to signal potential fitness costs during pregnancy, and such signals are often associated with spontaneous terminations. If however, nulliparous women who experience a fitness cost warning simply "choose" not to reproduce, they may mitigate the costs of a potentially failed reproduction. Women who choose not to reproduce may nonetheless enhance their reproductive fitness by means of inclusive fitness such as alloparenting the offspring of relatives. A questionnaire was administered in order to determine whether there is an association between any heritable diseases or medical conditions, or the use of an inclusive fitness strategy, and females who may or may not have chosen to have children. The questionnaire asked specific questions regarding their age, their decision whether or not to reproduce, individual health, health of relatives, and time invested in nieces and nephews. Statistical analyses utilizing logistic regression were performed to address these factors. The logistic regression indicated that there is a significant relationship between choice to reproduce and health of female study participants. Females who chose not to reproduce, or remain childfree, had a higher incidence of individual medical conditions, significantly higher than the female participants who have already reproduced or anticipated reproducing. The childfree females may have made the choice to abstain from individual reproduction because they experienced a fitness cost warning associated with their medical condition. This rare reproductive strategy is evolutionarily adaptive to females who may experience a fitness cost associated with individual reproduction. By making the “choice” to not reproduce, they are circumventing any lost time, energy, or resources associated with a failed or suboptimal reproductive event.