STUDY: Sex differences in the relationship between status and number of offspring in the contemporary U.S. “Analysis of U.S. data from the 1979 National Longitudinal Survey of Youth shows that personal income is positively associated with number of offspring for men, and this is true for men at all levels of education. This is mostly because of increased childlessness among low income men. For women, personal income is negatively associated with number of offspring, and this is true for women at all levels of education. Other measures of status (intelligence and education) are negatively associated with number of offspring for men and women, although the negative association is less for men.”