Sons are considered more valuable than daughters in India. Son preference is deeply rooted in various patriarchal practices, including a patrilineal inheritance system, a patrilocal marriage system, the social custom of dowry and the dependence of aging parents on sons.1-9 A major demographic outcome of son preference is that the proportion of living sons in a family influences the probability that the parents will procreate further. Known variously as differential stopping behavior, 10,11 son-targeting fertility behavior 1 and asymmetric procreation behavior, 12 childbearing driven by a desire for sons occurs when parents continue to progress to higher parities, within a maximum limit, until they have the desired number of sons. Parity progression driven by a desire for sons has several demographic and health ramifications. First, if prenatal sex detection and abortion are unavailable, parental desire for a certain number of sons will increase the average family size. Biologically, only 26% of couples who want two sons will have fulfilled this desire after two births. 12,13 Even after having six children, about 10% of couples will have been unable to achieve their goal of having two sons. Thus, to the extent that it is the prevalent means of fulfilling the desire for sons, parity progression delays India's demographic transition by keeping fertility rates higher than they would be otherwise, because parents who have not achieved their "son target" continue to procreate. 12,14,15 Indeed, the desire for sons is positively associated with the desire for more children 16,17 and the total fertility rate, 18 and negatively associated with contraceptive use. 16,17 In Nepal, for example, the fertility rate is about 6% higher than it would be in the absence of son preference.
15Second, parity progression driven by a desire for sons may result in imbalances in the sex ratio by family size. Although the desire for sons has considerable bearing on fertility, it does not distort the overall population sex ratio;19 if parity progression is the only method of fulfilling the desire for sons, then the population will be large but balanced. However, the desire for sons can skew the sex ratio by family size: Smaller families will have a disproportionate number of sons, because parents whose first children are male may decide to stop childbearing, while larger families will have a disproportionate number of daughters, because parents whose first children are daughters will likely continue having children. 1,10 Consequently, boys will tend to grow up in smaller families with fewer siblings and girls in larger families with more siblings, and girls will be more likely than boys to be born at earlier parities.