The preterm birth rate is up 8% from 2014

Preterm births in the U.S. are on the rise—and experts aren't entirely sure what's driving the increase.

Northwell Health partnered with Stacker to explore the rising rate of preterm births in the U.S. using CDC data. In 2022, 1 in 10 babies born in the U.S. were premature, an 8% increase since 2014 after a steady decline in the early 2010s. Babies born at less than 37 weeks of gestation are considered preterm; early term births, or those between 37 and 38 in utero, increased by 20% during the same period.

There's no one prevailing reason for the backslide in preterm births. Only 1 in 4 preterm births are medically induced, typically when a fetus is under stress due to an underlying condition. Many other established links to preterm births are already well-documented: smoking, recreational drug use, being under or over a healthy weight, and pregnancies with multiples. Although maternal age and some existing genetic conditions increase the risk of preterm births, none of these factors fully account for the startling rise.

Numerous factors may be at play, including one big one: Americans are getting sicker, according to Dr. Ellie Ragsdale, an OB-GYN-Maternal and Fetal Medicine specialist at the University Hospitals in Cleveland.

Ragsdale told CNN that increasing rates of obesity, high blood pressure, and gestational diabetes, conditions that can lead to preeclampsia and raise the risk of early delivery, are all contributing factors.

Babies born before reaching full-term tend to have lower birth rates and are at increased risk of health problems without the final weeks to develop their brain, lungs, and liver. In the short term, premature babies tend to remain in the hospital longer and may struggle with stomach and respiratory conditions. They're also more vulnerable to infections. Over the long term, they may experience developmental delays, chronic disorders like cerebral palsy, asthma, hearing loss, and issues with their heart, stomach, kidneys, teeth, and hormonal systems.

Many other, less direct factors that lead to preterm births result from the complex American makeup of social, economic, and environmental conditions. There are psychosocial factors, such as the impact of the pandemic and delayed access to health care. Environmental factors, like air pollution, also come into play; observational data published in the February 2024 issue of The Lancet Planetary Health journal links chemicals found in plastics to tens of thousands of preterm births in the U.S.

Estimates from the CDC show that of the nearly 20,000 infants that died in the U.S. in 2020, preterm birth and low birth weight were the second-leading causes of mortality. However, physicians believe that around half of preterm births in the U.S. are preventable, given that women with limited or no treatment for existing medical conditions and who lack access to maternal care services—which are more restricted in states with anti-abortion laws—are contributing to premature births.

A lack of access to insurance and, by extension, health care is also a factor. The most recent Census data shows that over 1 in 10 working-age Americans were uninsured in 2021. In Florida, where 1 in 6 women of childbearing age were uninsured in the same year, just over half of infants are born to women receiving adequate prenatal care, according to a March of Dimes analysis of Census data.

Editor's note: While this story centers on pregnancy and birth and uses gendered language in some cases when referring to data, we acknowledge that not all people who can become pregnant identify as women or mothers.