There may be new insight into the cause of miscarriages. Researchers said a simple ultrasound early in pregnancy can help predict miscarriage.

Researchers performed 1,800 Doppler ultrasounds on women early in pregnancy -- around six weeks after conception.

They found when there is normal heart function in the embryo, 95 percent of the pregnancies will continue.

However, when the ultrasound indicates abnormalities in heart function, 95 percent of those pregnancies do not continue.

Researchers said embryonic congestive heart failure was present in nearly all of the embryos that miscarried.

Previous research indicates that not enough oxygen gets to the embryo at an early, critical stage, and that the heart can't tolerate that stress, which leads to heart failure.

Giving oxygen through a face mask to pregnant women who are carrying an embryo at risk could be a simple remedy, but researchers said further study is needed before these recommendations be put into clinical practice.

The study is being presented Dec. 2 at the Radiological Society meeting in Chicago.

The research was done by Diagnostic Ultrasound Consultants in Oak Brook, Ill.