The New York City Health Department report said that in 2006 alone, more than half of all New York City pregnancies were unplanned and more than 60,000 new sexually transmitted infections were reported -- including 3,745 new HIV diagnoses.

Eleven percent of New Yorkers, about 610,000 adults, report having more than one partner in the past year, the report said. Men are three times more likely than women to report multiple partners -- 17 percent versus 6 percent and young adults are four times more likely than older adults to report multiple partners.

New Yorkers with same-sex partners are three times as likely as those with opposite-sex partners to report more than one partner in the past year. Five percent of New Yorkers who are married or in steady relationships say they've had two or more partners in the past year.

Sixty percent of New Yorkers with multiple partners reported using a condom the last time they had sex, but the proportion is 43 percent among New Yorkers in committed relationships who have had other partners in the past year.