Hypospadias Prevalence and Risk Factors in a United States Military Beneficiary Birth Cohort, 2010-2020

Introduction: Hypospadias is a congenital birth defect characterized by abnormal placement of the urethral opening in male infants. In the United States, hypospadias prevalence is estimated to be ∼60-80 per 10,000 male live births; however, reported estimates are higher among births to military beneficiaries. The present study leveraged a cohort of births among military families to investigate reportedly high hypospadias prevalence in a military birth cohort from 2010 to 2020. Materials and Methods: The Birth and Infant Health Research program data identified male live births among military medical (i.e., TRICARE) beneficiaries, January 2010 through December 2020. Hypospadias cases were identified in TRICARE claims data by 1 inpatient or 2 outpatient diagnoses during infancy; more conservative case definitions were also assessed (e.g., 2 diagnoses within (1) 1 year, (2) 3 months, and (3) 1 month of life). To examine characteristics associated with hypospadias, adjusted prevalence ratios (PRs) with 95% CIs were calculated using modified Poisson regression models. Results: The prevalence of hypospadias was 111.6 per 10,000 military-connected male live births. Estimates were high (>110.0 per 10,000) for both military and non-military pregnant parents, with PRs indicating a slight positive association for military parents (PR 1.07, 95% CI 1.00-1.14). Requiring 2 diagnoses by age 3 months yielded a prevalence of 79.5 per 10,000; associations by military status were attenuated (1.03, 95% CI 0.96-1.11). Conclusions: Reportedly elevated hypospadias among military-connected births is likely influenced by broad case ascertainment methods rather than military occupational exposures. These findings underscore the importance of evaluating differences in surveillance case definitions and considering associated data limitations (e.g., reliability of diagnosis codes) when comparing prevalence estimates.