Stillbirth is a tragedy that occurs in one of every 160 births in the United States. Compounding the sadness for many families, the standard medical test used to examine fetal chromosomes often can’t pin down what caused their baby to die in utero. In most cases, the cause of the stillbirth is not immediately known. The traditional way to determine what happened is to examine the baby’s chromosomes using a technique called karyotyping. This method leaves much to be desired because, in many cases, it fails to provide any result at all. Today, some 25 to 60 percent of stillbirths are still unexplained.