Teen pregnancy has long been a problem within the United States, reflecting larger issues of sexual health education and availability of contraception. Despite the CDC’s most recent report that pregnancy among adolescents has dropped a staggering 53 percent in 2009, teen birth rates remain an issue to be dealt with.

In order to fully understand teens more likely to engage in unsafe sex, researchers are looking to different groups of adolescents to find commonality between young mothers. One report has found that girls with mental illnesses are three times more likely to have children young, while a more recent study found an increase in pregnancy rates among obese teens.

Researchers from the University of Michigan Health System discovered that out of almost 1,000 teens, those who struggled with weight were significantly more likely to not use contraception during sex. Publishing their findings in the Journal of Pediatrics, a team of researchers under Dr. Tammy Chang of the U-M Medical School conducted a longitudinal study of over 900 women between the ages of 18 to 19, analyzing over 26,545 weekly surveys about adolescent sexual practices and contraception. It was there that they found the link between obesity and lack of contraception use.

“The U.S. teen pregnancy rate is one of the highest in the developed world and we know pregnant adolescents are more likely to have poor birth outcomes,” says Chang in a recent press release. “Reducing adolescent pregnancy is a national public health priority and we need to understand which adolescents are at higher risk of pregnancy. Our findings suggest that obesity may be an important factor associated with adolescent women’s sexual behavior.”

Researchers targeted their age bracket based on the knowledge that one quarter of women in the U.S. will become pregnant before 20 years-old, most frequently around the ages 18 or 19. Chang had also conducted a previous study finding another link between obesity and pregnancy, suggesting that women who have children in their teens are more likely to be obese as they get older.

Chang and her team are particularly concerned with their new findings, as obese women have greater risks of complications during pregnancy, including gestational diabetes, hypertensive disorders, blood clots, stillbirths and birth-related injuries. Babies born to obese mothers are also more likely require post-birth care in neonatal intensive care units.

“Understanding sexual behaviors by weight status among adolescents is critical because of the risk of dangerous outcomes for moms and babies associated with obesity,” said Chang.

Strangely enough, researchers did not find any other differences between overweight adolescents and their peers, concluding that practices like certain sexual behaviors, multiple partners, and frequency of sexual behaviors remained relatively the same. Researchers are still not sure what caused this difference, but hypothesize that low self-esteem, often a product of obesity, may cause these girls to not consider contraception as carefully before sex. Also, there may be a chance that socioeconomic differences which often contribute to obesity may lead to a lack of education among these young girls.

“By understanding the barriers that put certain groups of teens at higher risk of unintended pregnancies, clinicians and researchers can tailor interventions to empower adolescents to make healthier sexual choices,” concludes Chang.

Source: Chang T, et al. Sexual Behavior and Contraceptive Use Among 18 to 19 year old Adolescent Women By Weight Status: A Longitudinal Analysis. Journal of Pediatrics. 2015.