The nonprofit organization's latest report finds that more than 1 in 10 babies born in the U.S. last year were delivered at least three weeks before what's considered full term: 40 weeks of gestation. That marks a 4% increase from 2020.
"This is the highest preterm birth rate that we've ever recorded," said Dr. Zsakeba Henderson, the deputy chief medical and health officer for the March of Dimes, which began grading states for infant and maternal health in 2007.
People of color or those who live in impoverished areas are most at risk for premature birth.
"Black mothers and American Indian mothers continued to have increases" in preterm births last year, Henderson said. "That gap in disabilities continued to widen in this most recent report." Women of color, the report found, were 60% more likely than other women to give birth prematurely.
Babies born ahead of 37 weeks' gestation are at greater risk of myriad chronic health problems, such as asthma, blindness, deafness and intellectual disabilities.
The annual report gives the nation a D+ when it comes to preterm births.
"We are failing moms and babies," said Martha Wingate, the director of the Alabama Perinatal Quality Collaborative at the University of Alabama at Birmingham. "Regardless of who you are, if you are pregnant and deliver a baby in Alabama, you are at higher risk of dying, of your baby dying, period."
She attributed the disastrous situation for mothers and their newborns, in part, to differences in overall health in Alabama. The state has some of the highest rates of high blood pressure and Type 2 diabetes in the country.
One of the problems is that a large part of Alabama's population must drive hours to get help in emergencies.
"We have places in the state where women live two to three hours from the closest delivery hospitals," Wingate said. "Our outcomes shouldn't look like this. We can do better." Wingate has been charged with improving the state's preterm birth rate by improving maternal and fetal health.
Transportation is the "No. 1 barrier" in Arkansas, too, said Dr. Ashley Ross, the chief of neonatology at Arkansas Children's Hospital in Little Rock.
"Either they don't have reliable transportation or they're just so far away that they don't have the resources to afford to be able to drive this long distance on a regular basis to be able to access care," Ross said.
"It's hard to look at this trend," he said. "It's really heartbreaking."
Other states that got failing grades from the March of Dimes were Arkansas, Georgia, Kentucky, Louisiana, Mississippi, Oklahoma, South Carolina and West Virginia. All had preterm birth rates of at least 11.5%.
Only Vermont, with a preterm birth rate of less than 8.1%, scored an A.
CORRECTION: (Nov. 17, 2022, 8:51 a.m. ET): A previous version of this article misstated the rate of premature births in the U.S. last year. It was more than 1 in 10, not 1 in 100.