Mothers with partners who also identified as mothers have substantially higher rates of adverse pregnancy and birth outcomes than mothers with partners who identified as fathers, according to a new study.

Adverse outcomes include life-threatening complications such as postpartum hemorrhage.

The study of nearly 1.5 million births in California is the first population-based study to investigate obstetric health among sexual and gender minorities in the United States.

“We found that there is a diversity of parent structures in California, meaning different family constellations with different demographics and health outcomes,” says Juno Obedin-Maliver, an assistant professor of obstetrics and gynecology at Stanford University, and senior author of the study in American Journal of Obstetrics and Gynecology.

Doctors need to pay attention to the health risks associated with giving birth as part of a nontraditional family, she adds, because many of the risks, including elevated blood pressure, postpartum hemorrhage, and twin pregnancies, could be addressed with better medical care.

There is a growing need to understand the reproductive health of sexual and gender minorities, Obedin-Maliver says. More young adults identify as being in these groups than in the past, and they are now more likely to build families by giving birth.

“The disparities faced by people who were mothers in partnership with a mother were striking,” says lead author Stephanie Leonard, an instructor of obstetrics and gynecology.

“The crude observed rates of postpartum hemorrhage were about double compared with people in mother-father partnerships, and after we adjusted for confounding factors, hemorrhage risk was still about 40% higher. That was more than I had expected.”

Read the full article about pregnancy outcomes for two-mom families by Erin Digitale at Futurity.