A new test gives parents a sense of peace regarding their miscarriages.

There's a lot scientists don't understand about miscarriages, especially since some women miscarry so early, they never knew they were pregnant.

Experts believe at least half of early pregnancy losses are due to genetic abnormalities. Other causes include blood clotting disorders, thyroid imbalances and structural problems in the uterus.

Doctors can run an array of tests to determine the cause, but regardless of the findings, women often blame themselves, said Dr. Scott A. Sullivan, director of maternal-fetal medicine at the Medical University of South Carolina. A 2015 study found 47 percent of women reported they felt guilty after a miscarriage and 41 percent felt as though they had done something wrong.

While miscarriages occur in up to a quarter of known pregnancies — and about 1 percent of women experience three or more miscarriages — it is rare for patients to learn the reason why. Chromosomal abnormalities are by far the most common cause, but genetic tests on fetal tissue cost thousands of dollars, and results can take weeks. In most cases, genetic testing is not even offered until a patient has had three or more miscarriages.

Advances in rapid genetic testing may change that. By combining several new technologies, Dr. Zev Williams, director of the Columbia University Fertility Center in New York, has developed what he says is a faster, cheaper method to test fetal tissue for genetic abnormalities.

"Pregnancy loss has really been, from a patient's point of view, incredibly devastating to be going through, but from a medical and scientific point of view, a black box," Williams said. "We're starting to chip away at that."

Experts such as Cynthia Casson Morton, a medical geneticist at Brigham and Women's Hospital in Boston, said after reviewing Williams' research that the method looked promising. But she wasn't sure whether couples would want an answer that quickly: "It's a lot of information to handle all at once while they're grieving," Morton said.

Dr. Christine C. Greves, an obstetrician-gynecologist at Orlando Health Winnie Palmer Hospital, agreed that not everyone would be ready to hear test results right away, but she believed many would.

"Our human nature is wanting to know why," she said, "so if we could know why sooner, and it's accurate, then that probably could provide more of a sense of peace."