After years of decline, the number of premature births in the US has increased
The number of premature births has risen sharply in the US between 2014 and 2022, after years of steady decline, according to figures from Statistics Netherlands. recently published data from the Centers for Disease Control and Prevention. Experts say the shift may be partly due to an increasing prevalence of health complications among mothers.
“I'm not surprised that these are the changes we're seeing,” said Dr. Nahida Chakhtoura, chief of pregnancy and perinatology at the Eunice Kennedy Shriver National Institute of Child Health and Human Development. “We know that complications in mothers increase over the same period.”
The number of births before 37 weeks of pregnancy increased by 12 percent, although there were fluctuations during the years of the pandemic, with slight decreases in 2020 and 2022. The number of births in or after week 40 decreased during the study period. The increase in preterm births was similar across races and age groups, but the largest increase occurred among mothers age 30 and older.
It's a reversal of promising trends from before 2014, when preterm birth was rampant steadily decreasing and full-term deliveries increased. Although the latest report does not elaborate on the causes, it is “concerning,” said Dr. Chakhtoura, especially because premature babies are generally at increased risk for health complications.
One of the reasons for the increase could be that women are having children later in life, said Dr. Vanessa Torbenson, an obstetrician and gynecologist at the Mayo Clinic in Minnesota. Older maternal age, she added, carries an increased risk of health complications that may require early introduction. In particular, the number of cases of high blood pressure has generally increased in recent years. According to the CDCNearly 16 percent of women who gave birth in a hospital had some form of hypertensive disorder in 2019, and these problems were most common in women aged 35 and older. The rates of gestational diabetes are also grownespecially among older mothers.
In general, “the further along you go in the pregnancy, the better the chance of survival” for the baby, said Dr. Dawnette Lewis, director of Northwell Health's Center for Maternal Medicine and a specialist in maternal fetal medicine. Studies have found that a baby born at 23 weeks, for example, has about a 55 percent chance of survival, with chances increase every week then said Dr. Lewis. The American College of Obstetricians and Gynecologists advises to initiate labor on or before the 37th week, if medically necessary.
The latest CDC data is “skimming the surface,” said Dr. Lewis. One of the many unanswered questions is why there were few differences in preterm birth rates between different races, since research consistently shows that rates of preeclampsia and hypertension are disproportionately higher among black women. Understanding who was induced and why could shed some light on that question, she added.
Despite concerns about later maternal age, many of the health risks can be controlled, Dr. Lewis said. “Anyone considering pregnancy, regardless of age, should consult a healthcare practitioner so that they can be assessed and, if they do have any medical conditions, managed before attempting a pregnancy.”