• Posted October 28, 2025

30% of Stillbirths Occur With No Known Risk Factors, Study Shows

Even with modern prenatal care, thousands of U.S. families each year experience the heartbreak of stillbirth, and a surprising number happen without warning.

A study, published Monday in JAMA, analyzed nearly 2.8 million pregnancies and found that about 30% of stillbirths occurred with no clear medical cause or risk factor.

Researchers from the Harvard T.H. Chan School of Public Health and Mass General Brigham said their findings highlight major disparities that continue to affect Black families and low-income communities.

“Even when we know someone is at increased risk, our tools for prevention are still limited,” co-author Dr. Mark Clapp, an obstetrician at Massachusetts General Hospital, told The Washington Post. “Every stillbirth represents an unimaginable loss, not just for the mother but for the entire family, and is a reminder of how far we still have to go.”

Between 2016 and 2022, the study found, stillbirths occurred in about 1 in every 147 U.S. births. That’s higher than the 1 in 175 reported by the U.S. Centers for Disease Control and Prevention (CDC).

Rates were even higher in disadvantaged groups:

• 1 in 112 births among low-income families

• 1 in 95 births in communities with higher proportions of Black residents

Researchers said part of the discrepancy may stem from inaccuracies in reporting of fetal deaths.

Fetal death certificates vary in quality and definition across states, which can make national data inaccurate, according to Jessica Cohen, co-senior author and professor of health economics at Harvard.

More than 70% of stillbirths in the study involved at least one risk factor such as obesity, diabetes or substance use. But nearly a third occurred without warning, researchers said.

“It’s astonishing that in our day and age, so many stillbirths happen with no identified risk factors,” Cohen said. “We have watches that track our sleep and stress, but we can’t always tell when a pregnancy is in trouble.”

Risks rose sharply in pregnancies complicated by chronic high blood pressure, low amniotic fluid or fetal anomalies and after 41 weeks of gestation.

Stillbirth rates were highest in areas with limited resources, even among women with private insurance.

Researchers said this points to structural inequities and bias in maternal care, not just gaps in access.

“There is no biological reason for there to be almost triple the rate of stillbirths in American Blacks compared to whites,” Dr. Harvey Kliman, a placental researcher at Yale University who was not involved in the study, told The Post. “And that has been shown over and over again, and that disparity has not really improved.”

Families affected by stillbirth say the losses are often sudden and traumatic.

Jaye Wilson, a nurse from Maryland, lost her baby at 22 weeks after a placental abruption and said her experience of bias and disbelief from medical staff made the loss even harder. She later founded Melinated Moms, a nonprofit that supports mothers of color.

Samantha Banerjee, who lives in an affluent New York City suburb, lost her daughter two days before her due date and went on to start PUSH for Empowered Pregnancy.

“I’ll never forget the look on my cat Gio’s face as I was walking out the door to the emergency room,” Banerjee told The Post. “He had been with me throughout my entire pregnancy, and in that moment, I just knew something was wrong.”

More information

The U.S. Centers for Disease Control and Prevention has more on stillbirth.

SOURCE: The Washington Post, Oct. 27, 2025