More U.S. women are dying from pregnancy or childbirth complications today than in recent history, causing alarm stateside as maternal mortality drops worldwide.

The United Nations set a goal to reduce the global maternal mortality rate by 75% between 1990 and 2015, and while most nations succeeded in lowering that number, the U.S. has experienced an uptick in recent years. A report published in the September issue of the journal Obstetrics & Gynecology found that from 2000 to 2014, the maternal mortality rate for 48 states and Washington, D.C. increased 27% from close to 19 deaths per 100,000 live births to close to 24 deaths per 100,000 live births. In Texas, the rate doubled between 2010 to 2012.

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Another recent report from the Institute for Health Metrics and Evaluation reported a rise in the U.S. maternal mortality rate since 2000 (with a slight drop in the past two years), and a 2015 report from the World Health Organization (WHO) pointed out that the U.S. has a higher maternal mortality rate than Iran, Libya and Turkey. The WHO determined that half of the U.S. deaths were preventable.

“This is a really important issue,” says Marian MacDorman, author of the Obstetrics & Gynecology study and a research professor at the University of Maryland. “These are deaths of young women with families and often young children who need care.”

Here’s what may be at play:

Record keeping problems: National data on maternal mortality is inconsistent, and some health authorities argue that the uptick in maternal deaths is at least partially due to improved detection of pregnancy-related deaths. However, MacDorman says the 27% increase observed in her study is a true rise in maternal deaths, rather than a reporting issue.

More American women are obese: America’s growing obesity problem is a factor. There’s also a growing number of pregnant women in the U.S. with chronic health problems like high blood pressure, heart disease, and diabetes—all of which put women at a greater risk for complications during pregnancy. According to the CDC, heart-related problems make up a substantial portion of pregnancy-related deaths.

Access is inconsistent: Between 2000 to 2015, Texas saw a spike in maternal mortality while the state also underwent changes to reproductive health services, including the closure of several clinics offering abortions and other services. In 2011, the state’s family planning budget was cut by two-thirds. Experts say the lack of access is probably not solely responsible for the state’s dramatic spike in deaths, but as The Texas Tribune reports, it may have exacerbated the issue. “I’ve done my best to try to investigate this as a data error and I can’t find any changes to account for it,” says MacDorman. “It’s very concerning what’s happening in Texas.”

Racial disparities persist: Black women in the United States are up to three times more likely to die in pregnancy and childbirth compared to white women. While they are not significantly more likely to develop conditions like hemorrhage and preeclampsia—which threaten a women’s health during childbirth—they are more likely to die from them.

Rise in cesarean births: The rates of c-section deliveries among American women rose 53% from 1996 to 2007, now accounting for 32% of births. “Cesarean has its place, and it has saved the lives of mothers and babies,” says Dr. Michael Lu, an associate administrator with the Maternal and Child Health Bureau at the Health Resources and Services Administration. “But cesarean has its complications and these can increase the risk of maternal death.” C-sections require intensive surgery, and are associated with higher health and safety risks for mothers and infants.

Women are having children later: Lu says older women are at a greater risk for maternal mortality, with a couple caveats. “It’s not clear whether it’s age, or that older women have more chronic conditions when they enter pregnancy,” he says. “The demographic of childbearing is changing. Women are getting older and they are entering pregnancy with more conditions like obesity, diabetes, and heart disease.” To combat the problem, Lu says his department is focusing on improving the health of women before they get pregnant, and improving the quality and safety of maternal health care nationwide.

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