Sex with an uncircumcised man puts female partners at greater risk for cervical cancer, a new study has found, fuelling debate about the medical worthiness of circumcision, a procedure that has increasingly come under criticism.

Researchers studied the sexual habits of 1,139 men from Brazil, Colombia, Thailand, the Philippines and Spain. They found 166 of the 847 uncircumcised men had penile HPV, while only 16 of the 292 circumcised men carried the virus.

Researchers offered few explanations as to why a foreskin would encourage the transmission of HPV, but speculated that uncircumcised men may be more susceptible to infection because the foreskin folds back during sex, exposing the penis to vaginal secretions and offering the virus more access to the penis.