A new federal study finds that two-thirds of women of childbearing age in the United States have at least one risk factor for birth defects that could be reduced through lifestyle or medical interventions.
The report, published Tuesday in the American Journal of Preventive Medicine, analyzed survey responses from more than 5,300 women ages 12 to 49 collected between 2007 and 2020. Researchers identified five key risk factors: obesity, diabetes, smoking exposure, food insecurity and low levels of folate, a B vitamin essential for cell development.
According to the Centers for Disease Control and Prevention (CDC), 66% of women had at least one of these risk factors, and about 10% reported three or more.
Risks Begin Early in Pregnancy
Birth defects affect roughly one in 33 U.S. newborns and are the leading cause of infant mortality. Many risks arise before a woman realizes she is pregnant, underscoring the importance of early prevention.
“We can’t underscore enough how important it is to raise awareness,” said Arick Wang, a CDC health scientist and lead author of the study. “Risks can be lowered through steps like getting the recommended 400 micrograms of folic acid daily, healthy diet and exercise, and managing blood sugar.”
Low folate levels, for example, are closely linked to neural tube defects — serious brain and spinal cord abnormalities that form in the first month of pregnancy. Since 1998, the Food and Drug Administration has required folic acid fortification in grain products, a measure the CDC estimates prevents more than 1,300 neural tube defects annually.
Obesity and Other Factors
Obesity was the most common modifiable risk factor in the study, affecting about one-third of women surveyed. Though the precise biological link to birth defects is unclear, researchers suspect that metabolic changes, including disruptions in insulin and glucose regulation, may impair fetal development.
High blood sugar from diabetes poses similar risks, while chemicals in cigarette smoke, including nicotine, can restrict oxygen flow to the fetus. Food insecurity can also deprive women of nutrients critical to fetal organ formation.
“When cells are growing and forming organs, we really rely on everything to be working just as it should,” said Dr. Michael Warren, chief medical and health officer at March of Dimes. “When you disrupt those processes, things can go awry.”
Warren added that many women may not realize obesity and food insecurity are significant risk factors, noting that broader access to nutritious food and safe spaces for physical activity could reduce risks.
Policy Challenges
The study’s release comes amid uncertainty over CDC staffing. In March, the Department of Health and Human Services announced plans to cut 2,400 agency jobs. A federal judge has since blocked some of the layoffs, including those affecting the CDC’s National Center on Birth Defects and Developmental Disabilities — the unit behind the study. Still, at least 600 employees are expected to lose their jobs.
Wendy Nembhard, director of the Arkansas Center for Birth Defects Research and Prevention, welcomed the study’s findings given the climate of funding cuts. “We’re delighted this study has been ongoing,” she said.
Warren pointed to broader systemic challenges, citing Mississippi’s recent public health emergency declaration over high infant mortality and its pledge to eliminate “care deserts” where pregnant women lack access to obstetric services.
Despite advances such as folic acid fortification, many questions remain unanswered. “The vast majority of birth defects that occur, we still don’t know why they occur,” Nembhard said. “Even when women do everything right, outcomes are not always what we hope for.”
