A longitudinal 25-year study conducted in New Zealand supports the claim that circumcised males are at considerably less risk of acquiring sexually transmitted infection (STI) than uncircumcised males. Data were collected for 510 males, almost one third of whom were circumcised. All these individuals were studied at birth, 4 months, 1 year, and at annual intervals to 16 years and again at ages 18, 21, and 25. Confounding variables-social, family, and individual factors-were also used in the analysis of the association of circumcision and self-reported STIs.
At ages 18 to 21, uncircumcised males were more than 2.5 times as likely as circumcised males to have an STI. Risks of STI were unrelated to all measures of childhood social background, such as maternal age and education and family socioeconomic status, and to birth weight. Even adjustment for the number of sexual partners and engaging in unprotected sex did not reduce the association between circumcision status and self-reports of STI. Investigators estimated that universal neonatal circumcision would have lowered rates of STIs in the study group by almost half (Fergusson DM et al: Pediatrics 2006;118:1971).