HIGH PREVALENCE OF VOLUNTARY STERILIZATION AMONG AMERICAN WOMEN EXPLAINED BY TRADE-OFFS RESULTING FROM MALE PARENTAL COMMITMENT.

Tubal ligation is the modal form of family planning among American women aged 30 and older. As the preference for tubal ligation over cheaper, lower risk and more reliable methods, such as vasectomy, has puzzled experts, a theoretical approach that explains this preference would be useful. The present study investigates the high prevalence of voluntary sterilization among American women from the perspective of life history theory, arguing that the trade-offs between investing in current and future offspring will favour tubal ligation when women cannot obtain reliable male commitment to future parental investment. Data came from the National Survey of Fertility Barriers (NSFB), a nationally representative survey of 4712 American women aged 25-45 conducted between 2004 and 2007. Four novel predictions of the prevalence of tubal ligation, drawn from life history theory, were developed and tested: 1) it is most common among unpartnered women with children, and least common among married women with children; 2) it is negatively correlated with age at first birth; 3) it is least common among highly educated women without children, and most common among less educated women with children; and 4) among women with two or more children, it is positively correlated with lifetime number of long-term partners. These predictions were tested using multivariate regression analysis. The first prediction was not supported: women with children were more likely to be sterilized, regardless of their marital status. The other three predictions were all supported by the data. The results suggest that trade-offs influence women's decisions to undergo voluntary sterilization. Women are most likely to opt for tubal ligation when the costs of an additional child will impinge on their ability to invest in existing offspring, especially in the context of reduced male commitment.