NEW HAVEN, Conn. (WTNH) – Many women have a history of unsuccessful pregnancies.

For some, every pregnancy ends in a loss within six weeks.

“These particular patients always have losses and they are not infertile. They get pregnant easily but they always have these losses,” says Dr. Harvey Kliman, director of the Reproductive and Placental Research Unit in the Department of Obstetrics, Gynecology and Reproductive Sciences at Yale School of Medicine.

That led to a Yale School of Medicine and University of Illinois at Chicago study, co-authored by Dr. Kliman.

He further explained, “Could it be that the endometrium, the lining of the uterus was not supporting the early embryo?”

To find out, Dr. Kliman used a test, which he created, on 116 women with recurring pregnancy losses.

“We actually used a molecular marker, a molecular test called the endometrial function test to look at the endometrium to see which patient had an abnormal endometrial development,” said Kliman.

Those abnormal, were identified as women who needed more of the hormone progesterone.

“Pregnancy is absolutely dependent on progesterone. Without enough progesterone, that’s the end of the pregnancy actually,” said Kliman.

The pregnancy rate was high among women in the study with unsuccessful pregnancies.

“After they got treated with progesterone, their success rate was above 60 percent. So they went from basically having no successful pregnancies to having rates that are very similar to normal healthy women,” said Kliman.

The results are published in the current issue of Fertility & Sterility, the international journal of American Society for Reproductive Medicine.