Objective: To determine if there was an association between vasectomy utilization and offspring sex ratio (male offspring : total offspring), as offspring sex preference may have an impact on family planning in the United States.
Methods: Using data from the National Institutes of Health-AARP Diet and Health Study, we calculated the number of sons and daughters of all men stratified by vasectomy status. We utilized a logistic regression model to determine if vasectomy utilization varies based on offspring sex ratio while accounting for known factors that impact vasectomy utilization.
Results: Of these men, 30,927 (30.8%) underwent vasectomy. Marital status, race, age, education level, region or state, and number of offspring were all significantly correlated with vasectomy utilization (P < .01). The sex ratio for vasectomized fathers (51.3%) was significantly higher than for fathers who had not undergone vasectomy (50.7%, P < .01). This difference remained even after we stratified by the total number of offspring: vasectomized men with 4 or more children had a sex ratio of 947 girls per 1000 boys, whereas the no vasectomy group had a sex ratio of 983 girls per 1000 boys (P < .01). For men with at least 2 children, each additional son increased the likelihood of vasectomy by 4% (P < .01), whereas each additional daughter led to a 2% decrease in vasectomy utilization (P = .03).
Conclusion: Vasectomized fathers have a higher proportion of sons compared with non-vasectomized fathers, suggesting that offspring sex ratio is associated with a man's decision to undergo vasectomy. Further research is indicated to understand how offspring sex ratio impacts a man's contraceptive decisions.
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