Levels of anti–clotting proteins influence pregancy outcomes

Recurrent miscarriage, stillbirth, preeclampsia, poor fetal growth, preterm delivery and bleeding in pregnancy are influenced by low levels of the anti–clotting proteins Z and S, Yale School of Medicine researchers report in the March issue of Journal of Thrombosis and Haemostasis.

"Our findings will help clinicians determine early in pregnancy, which women will have healthy pregnancies and which women will develop complications," said lead author Michael Paidas, M.D., associate professor and director of the Program for Thrombosis and Hemostasis in Women's Health, Department of Obstetrics, Gynecology & Reproductive Sciences at Yale School of Medicine. Paidas conducted the study with colleagues at the Bio–Reference Laboratory (Elmwood Park, New Jersey).

Low levels of a novel anti–clotting factor, protein Z, and protein S early in pregnancy may act together with other genetic clotting tendencies to adversely affect pregnancy, according to the study. Testing for these proteins can help determine which women with inherited clotting problems are at risk for pregnancy complications and how they should be treated.

The study included 103 women with normal pregnancies, 106 women with pregnancy complications, and 20 women with inherited clotting conditions, which affects about 20 percent of Caucasian women. "In early pregnancy, patients with low levels of protein Z have a four–fold higher risk of pregnancy complications," said Paidas. "Based on our data, we speculate that protein S free antigen levels below 29 percent may be associated with clotting related pregnancy complications."

About 15 percent of U.S. pregnancies each year are marked by complications, putting these women at higher risk for complications in future pregnancies. Paidas said this study leads the growing evidence that inherited clotting conditions can dramatically add to the risk of pregnancy complications.

Women with prior pregnancies complicated by fetal loss, preeclampsia, growth restriction or bleeding, may contact Paidas at Yale Maternal–Fetal Medicine, 203–785–5682 for testing.

Other authors on the study are D–H W. Ku, M–J. Lee, S. Manish, A. Thurston, Charles J. Lockwood and Y.S. Arkel.