Within a two-year period between 2010 and 2012, the rate of pregnant women dying in Texas doubled – and it’s not entirely clear why.

According to a study published in the September issue of the journal Obstetrics and Gynecology, “after 2010, the reported maternal mortality rate for Texas doubled within a 2-year period to levels not seen in other U.S. states.”

In 2011, the state Legislature cut Texas’ family planning and women’s health program, which provides care and routine screenings for low-income women. Lawmakers slashed its budget by two-thirds — and kicked out women’s health providers that also provide abortions.

"In the absence of war, natural disaster, or severe economic upheaval, the doubling of a mortality rate within a two-year period ... seems unlikely."

And while other studies found that move led to a spike in unplanned pregnancies and severely limited access to family planning, this latest research suggests these changes alone can’t definitively account for the spike in deaths among pregnant women.

“There were some changes in the provision of women’s health services in Texas from 2011 to 2015, including the closing of several women’s health clinics,” researchers note. “Still, in the absence of war, natural disaster, or severe economic upheaval, the doubling of a mortality rate within a two-year period in a state with almost 400,000 annual births seems unlikely.”

Researchers also note that they “did not identify any data processing or coding changes that would account for this rapid increase.”

In short, they are stumped.

“I think it’s very unusual,” said Dr. Marian MacDorman, a research professor at the Maryland Population Research Center at the University of Maryland and one of the authors of this study.

“I didn’t see this in other states.”

MacDorman says she and the other authors of this study were so intrigued they have already begun another study to try and figure out what happened.

“We are in the process of doing a follow up study to try to analyze this study in more detail,” she says.

MacDorman also notes maternal mortality rates are still a problem in Texas. The latest figures – from 2014 – remain at “a higher level.” She says this is something that should concern public health officials in Texas.

“It’s a great concern,” she says. “Maternal deaths are deaths of young women that have families. They probably have other children they have husbands. The ripple effect is huge for these deaths.”

The study also found the maternal mortality rate nationwide is a problem, too.

The study found the “estimated maternal mortality rate (per 100,000 live births) for 48 states and Washington, DC (excluding California and Texas, analyzed separately) increased by 26.6 percent, from 18.8 in 2000 to 23.8 in 2014.”

“Clearly at a time when the World Health Organization reports that 157 of 183 countries studied had decreases in maternal mortality between 2000 and 2013, the U.S. maternal mortality rate is moving in the wrong direction,” researchers noted.