As usual with studies promoting circumcision, there are problems: did they control for penis size? Unsurprisingly, bigger foreskins are usually found (or in this case, taken from) bigger penises. Do men with bigger penises have more trouble using condoms? Do they have more confidence and hence more sex? Either could account for the correlation Kigozi et al. found.

Kigozi at al. have published several studies demonising the foreskin, apparently with a view to promoting circumcision, but perhaps that tends to narrow their focus. For example they cut short the study about male transmission to women (Lancet 374;9685, pp 229-37) before it reached statistical significance. It looked as though it was going to show that circumcising men increased the risk to women.