Only 23 percent of women in New York City always used condoms during anal sex in the past year, compared with 61 percent of men who have sex with men, according to a new study by the New York City Health Department.

Unprotected anal sex puts a person at high risk for HIV and other sexually transmitted infections (STIs). Past studies have found anal exposure to HIV poses 30 times more risk than vaginal exposure.

According to the study, titled “Women, Unprotected Anal Sex and HIV Risk,” 943 women in New York City contracted HIV in 2008.

The study also found that women who have anal sex without condoms are less likely to get regular STI tests, including HIV tests, than women who consistently use condoms.