The first prospective study into the outcome of untreated pregnancies in a group of women carrying a mutation in the Factor V Leiden gene** and with a history of recurrent miscarriages at around 12 weeks, showed that under 40% had live births compared with nearly 70% in a control group of women with a similar history but with a normal copy of the gene.
For women with the rogue gene who had a history of late miscarriage only one out of nine had a live birth compared with 22 out of 45 of the women with the normal gene.
The research was carried out by teams from the Department of Reproductive Sciences, Imperial College of Science, Technology and Medicine, London, and the Department of Haematology, St. Marys Hospital NHS Trust, London.
Pregnancy complications associated with the mutated gene and other genetic mutations affecting the blood clotting mechanism are thought to be due to thrombosis in the blood vessels of the placenta.
Now the researchers have called for doctors to screen women for Factor V Leiden (FVL) mutations if they have a history of recurrent miscarriages associated with placental thrombosis. They also want targeted anti-blood clotting treatment for these women to be tested in a randomised clinical trial.
Dr Raj Rai, Clinical Lecturer in Reproductive Medicine at Imperial College and co-author of the study, said that it was important to stress that many women with the mutation had perfectly normal pregnancies: it was likely to be the women who had multiple risk factors for thrombosis that were most at risk of miscarrying.
"However, the low live birth rate in our study suggests that Factor V Leiden is an important and potentially
Contact: Margaret Willson
European Society for Human Reproduction and Embryology