Each year, nearly 21,000 infants in the U.S. are stillborn. In many cases, doctors can't explain why a child died.

"The loss of an unborn child, as you can imagine, is a devastating experience. It's especially devastating for expectant couples losing a baby after 20 weeks gestation, which we define as stillbirth in the U.S.,” said Dr. Tsegaselassie Workalemahu, a researcher at the University of Utah.

Researchers think many of these deaths may be preventable. A new study is the first to show stillbirth can be inherited through a couple's male relatives,

The risk is even higher when the condition is passed down from the father's side.

The team studied thousands of stillbirth cases and live births.

Nearly 400 families had numerous stillbirths over multiple generations, which researchers say suggests there's a genetic cause of death.

"This kind of study, if validated, could help clinicians provide information that can be helpful to patients manage subsequent pregnancies and understand the family contribution to stillbirth risk in general,” said Workalemahu.

He says the next steps include identifying specific genes that cause unexplained stillbirths. The hope is this research will one day lead to better diagnosis and prevention and ultimately reduce the number of deaths.