The compelling reason to have a Brit Milah (Circumcision) is because we were commanded to do so by the Almighty; However, science and medicine tell us that there are many medical benefits to Brit Milah, as well.
Medical research from all over the world repeatedly demonstrates the protective effect of circumcision on the transmission rates common sexually transmitted diseases, including HIV (AIDS), as well as varied strains of the human papillomavirus (HPV), to name just a few. Additionally, research has demonstrated repeatedly that circumcised men have a dramatically lower incidence of penile cancers, which, though rare in the western world, have very high mortality rates worldwide.
In fact, various different studies among different populations, worldwide have come repeatedly to a single conclusion: After ignoring or adjusting for all other factors, circumcision reduces the risk of contracting HIV or HPV by up to 60%. A similar protective effect is realized for many other diseases. In fact, numerous African nations, ravaged by the AIDS epidemic, have elected to include circumcision in their programs for fighting AIDS, alongside retroviral therapies, prophylactic distribution, education, and other proven strategies. In fact, one study found the protective effect of circumcision so compelling that the study was terminated so that all uncircumcised participants could be offered circumcision.
Additionally, these health benefits are not only for men! Circumcised men pass on these benefits to their wives; Reduced infection rates for men naturally mean reduced infection rates for their partners. But, even more importantly, circumcision significantly lowers the rates for contraction and re-transmission of various strains of HPV (human papillomavirus), a virus that (while its effect on men is unclear) has been proven to cause the majority of cervical cancer in women.
Below is a selection of various articles collected by Brit Yosef Yitzchak that address these varied issues and research.
Effect of neonatal circumcision on penile neurologic sensation
Penile sensitivity and sexual satisfaction after circumcision: are we informing men correctly?
Ugandan Government Sees Circumcision as HIV Infection Deterrent.