A few months ago, Wawer et al. published results of an RCT showing that the male's circumcision status had no effect on male to female transmission of HIV. Now, Weiss et al. have published a meta-analysis of studies addressing this aspect. Their meta-analysis includes Wawer's study (I assume; I haven't read the full text, but am unaware of any other RCTs) as well as six observational studies. They report:
A random-effects meta-analysis of data from the one randomised controlled trial and six longitudinal analyses showed little evidence that male circumcision directly reduces risk of HIV in women (summary relative risk 0.80, 95% CI 0.53-1.36).This news will no doubt be disappointing for many, as there were hints that circumcision might protect against multiple transmission routes, but the evidence suggests otherwise. As Weiss et al. note, further RCTs - needed to settle the question - are unlikely to occur.
Still, we must not forget the indirect benefit to women: reducing the risk of a male acquiring HIV in turn reduces the probability that he will pass it on to a partner.