Childhood maltreatment and bullying may partially explain why lesbians and bisexual women have higher rates of teen pregnancy than their heterosexual peers, according to a new study published in the journal Pediatrics.

Young lesbians and bisexual women are roughly twice as likely as those who identify as heterosexual to have a teen pregnancy, according to previously published research, and this new study — conducted by researchers at Harvard, the City University of New York and San Diego State — set out to explore what factors contributed to the disproportionate rates.

Their report, "Teen Pregnancy Risk Factors Among Young Women of Diverse Sexual Orientations," gathered data from 7,120 young women of all sexual orientations to examine teen pregnancy risk factors, such as childhood maltreatment, bullying (as both perpetrators and victims) and gender-nonconformity. Among sexual minorities, developmental milestones and sexual orientation-related stress were additionally examined, as well as "outness" and social involvement in the LGBTQ community.

The study found childhood maltreatment, like being rejected by a family member, and bullying were "significant teen pregnancy risk factors" among all participants, but they were more prevalent among lesbian and bisexual women, which researchers found explains part of the disparity.

Dr. Cora Breuner, chairperson of the Committee on Adolescence at the American Academy of Pediatrics, which publishes the journal Pediatrics, told NBC News the results of the study corroborated what clinical groups have known for a long time.

"Those of us who work in the field weren't surprised," she said. "We were relieved to be right, but disheartened as you can imagine for [young bisexual or lesbian women] struggling to figure out who they are to then have an unintended pregnancy to occur."

Although it has not been studied, the report speculated young bisexual and lesbian women might engage in sexual behaviors that put them at risk for teen pregnancy in order to "prove" to bullies that they are heterosexual.

"Young women who are sexual minorities may view sexual intercourse with men and pregnancy as a way to stay 'closeted,'" the report states.

Breuner added that the lack of comprehensive sex education in schools and the lack of access to contraception add to the teen pregnancy risk factors for sexual minority women.

"The important thing to remember is they're not thinking they can get pregnant, and providers who take care of them aren't asking them about contraception," Breuner said.

Women across the sexuality spectrum who presented as more feminine were shown to be at greater risk for teen pregnancy, which, the report stated, might be due to the "gender intensification hypothesis," which posits that young people experience increased pressure to conform to culturally sanctioned gender roles during adolescence.

"Young women who are the most gender-conforming (i.e., most feminine) may be the least prepared to negotiate contraception with a male partner, elevating their risk of pregnancy," the report stated.

Heron Greenesmith, an attorney and policy analyst who writes about bisexual communities, told NBC News many avenues, like contraception and abortion, are sealed off for bisexual and lesbian young women due to stereotypes, such as believing bisexual and lesbian women can't get pregnant. She also noted that young bisexual women face additional stressors, like rejection from both their straight and gay peers after coming out.

"We look at experiences of bi students and pansexual students, and found that they participated in GSAs (Gay-Straight Alliances) at far lower rates," she said. "So few bi people are out to the important people in their lives, so you have these kids in crisis without support and without sex education in their school."

To mitigate disparities in teen pregnancy rates, the study points to factors like community involvement to reduce the risks of "gender intensification" and reduce the likelihood of having to be in the closet, both thought to be contributing elements to teen pregnancy in young lesbian and bisexual women.

"Being involved with the LGB (lesbian, gay and bisexuality) community through activities like LGB social or educational events confers social support and may act as a buffer to risk factors," the report stated.

It also noted that teen pregnancy prevention efforts that focus on risk factors more common among young bisexual and lesbian women, like childhood maltreatment and bullying, could help to reduce the disparity.

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