Pregnancies are more common among lesbian, gay, bisexual youths than among their heterosexual counterparts, suggests a new study of New York City high school students.

Overall, sexual-minority students who were sexually active were about twice as likely as other students to report becoming pregnant or getting someone pregnant, researchers found.

"The message for me is that these populations are often ignored or assumed to not need information or reproductive care or services and they absolutely do," said Lisa Lindley, the study's lead author from George Mason University in Fairfax, Virginia.

Previous studies had found an increased risk of pregnancies among sexual minority youths, but those data were old and mostly collected for girls only.

"I was just curious more than anything to repeat one of the studies that was done to look at teen pregnancy among sexually experienced young people," Lindley told Reuters Health.

For the new study, reported in the American Journal of Public Health, the researchers used data from nearly 10,000 ethnically and racially diverse New York City high school students from 2005, 2007 and 2009. They included only students who reported having sex with a member of the opposite sex.

Students were identified as a sexual minority if they identified as lesbian, gay, bisexual, or had reported sex with someone of the same sex.

About 85 percent of female students identified as heterosexual and about 90 percent only had male sexual partners. Of the male students, 96 percent identified as heterosexual and 97 percent only had female sexual partners.

About 14 percent of females became pregnant, and about 11 percent of males got someone pregnant.

Overall, about 13 percent of heterosexual females and about 14 percent of females who only had male sexual partners had been pregnant, compared to about 23 percent of lesbian or bisexual females and about 20 percent of girls who had male and female sexual partners.

About 10 percent of heterosexual males and those who only had female sexual partners experienced a pregnancy, compared to about 29 percent of gay or bisexual males and about 38 percent of males with female and male sexual partners.

"What really accounted for most of the risk for the girls was sexual behavior," Lindley said. "Basically the earlier they initiated intercourse and the more partners they had the more likely they were to become pregnant."

The survey data also included students' responses to a question about ever having been forced to have sex against their will.

For boys, behavior also accounted for a significant part of the increased risk, Lindley said. But, "what was different for the boys is if they were ever forced to have sex, they were more likely to cause a pregnancy."

The researchers point out there are likely other factors that contributed to an increased risk of pregnancy among sexual minority students, such as stigma and discrimination, lack of support resources and fewer connections to family and school.

"Documenting these disparities is the first step toward reaching health equity," said Brittany Charlton of Harvard Medical School and Boston Children's Hospital. "Every one of us can help to lessen this burden."

For example, she told Reuters Health in an email, healthcare providers can become better trained to meet the needs of lesbian, gay and bisexual people. Public health specialists could design more inclusive teen pregnancy programs targeting socially marginalized groups. Teachers can also make sure all students are equipped with comprehensive sex education and knowledge to make healthy decisions.

"Finally, parents can ensure their children are supported and have access to requisite reproductive healthcare," said Charlton, who researches teen pregnancy among sexual minority youths but was not involved with the current study.

She cautioned that while the new study confirms past findings, it can't untangle nuances in pregnancy rates between subgroups, such as lesbians compared to bisexual women.

Lindley also cautioned that the new study does not represent all lesbian, gay and bisexual youths - only those who had sex with a person of the opposite sex.