After years of decline, premature births rise in U.S.

Premature births, after years of steady decline, rose sharply in the U.S. between 2014 and 2022, according to recently published data from the Centers for Disease Control and Prevention. Experts said the shift might be partly the result of a growing prevalence of health complications among mothers.

“I’m not too surprised that these are the changes we’re seeing,” said Dr. Nahida Chakhtoura, chief of the pregnancy and perinatology department at the Eunice Kennedy Shriver National Institute of Child Health and Human Development. “We know that maternal complications have been on the rise for the same time period.”

Births before 37 weeks of gestation increased by 12%, although there were fluctuations during the pandemic years, with slight decreases in 2020 and 2022. Deliveries at or after week 40 declined during the study period. Increases in premature birthrates were similar across races and age groups, but the largest jump was among mothers 30 and older.

It is a reversal of promising trends before 2014, when premature births had been steadily declining and full-term deliveries were on the rise. Although the latest report doesn’t delve into the causes, it is “concerning,” Chakhtoura said, particularly because premature babies generally face increased risks for health complications.

One of the reasons for the rise might be that women are having babies later in life, said Dr. Vanessa Torbenson, an obstetrician and gynecologist at the Mayo Clinic in Minnesota. Older maternal age, she added, presents an increased risk of health complications that may require an early induction. Overall rates of high blood pressure in particular have been on the rise in recent years. According to the CDC, almost 16% of women who delivered in hospitals had some kind of hypertensive disorder in 2019, and those issues were most common among women 35 and older. Rates of gestational diabetes have also grown, especially among older mothers.

Generally, “the further along you go in pregnancy, the higher the chance of survival” for the baby, said Dr. Dawnette Lewis, director of Northwell Health’s Center for Maternal Medicine and a maternal fetal medicine specialist. Studies have found that a baby delivered at 23 weeks, for example, has a roughly 55% chance of survival, with chances increasing each week after that, Lewis said.

The American College of Obstetricians and Gynecologists recommends inducing labor at or before 37 weeks when medically necessary.

The latest CDC data is “skimming the surface,” Lewis said.

One of the many unanswered questions is why there were few differences in premature birthrates across races, given that research consistently shows that rates of preeclampsia and high blood pressure are disproportionately higher among Black women.

Understanding who was induced and why might shed some light on that question, she added.

Despite the concerns around later maternal age, many of the health risks can be managed, Lewis said.