Predicting miscarriage

A simple protein might predict the chances of a pregnancy ending in miscarriage, say researchers in Australia1.

About half of all fertilized eggs are aborted, often before the woman knows she is pregnant. Among known pregnancies, roughly 10-15% of pregnancies are spontaneously lost. Yet doctors often can't foretell which ones will fail. One of the few known hints is a hormone called human chorionic gonadotrophin (hCG), whose levels fall around the time of a miscarriage.

The Australian study now shows that levels of a protein called MIC1 - one of a host of immune-system proteins that exist during pregnancy and which are thought to be critical for a healthy pregnancy - drop by 70% as early as three weeks before a miscarriage, long before hCG levels fall.

Stephen Tong at Monash University in Clayton, Australia, and his team tested the blood of 200 women who were 6-13 weeks into a healthy pregnancy and another 100 women who subsequently miscarried1. The results make M1C1 the earliest indicator that things are going awry, says pregnancy researcher Joan Hunt of the University of Kansas Medical Center in Kansas City. "I don't know of another molecule that precedes hCG."

Falling MIC1 levels might serve as a predictive test to warn of a failing pregnancy, Tong suggests.

Exactly what MIC1 does is unknown. But it might, for example, dampen down inflammation caused when an embryo implants, suggests Galit Sarig, who studies pregnancy loss at Rambam Medical Centre in Haifa, Isra!.

The correct balance of such molecules might also stop the mother's immune system from attacking her own embryo. Women who suffer recurrent miscarriage are often found to have an abnormal balance of these proteins.

Researchers hope that this and other studies might eventually lead to drugs that prevent miscarriage by, perhaps, boosting levels of MIC1 back to normal. This might be particularly helpful for women who suffer recurrent pregnancy loss. But for now, "that is just pie in the sky", says Hunt.

References
1. Tong, S. et al. Serum concentrations of macrophage inhibitory cytokine 1 (MIC 1) as a predictor of miscarriage.Lancet, 363, 129 - 130, (2004).

HELEN PEARSON