There is now more evidence that women who have two copies (are homozygous) of mutations for genes that can cause inappropriate blood clotting (thrombophilia) are not as likely as previously thought to suffer from some pregnancy complications. The Jamuary 2010 issue of the medical journal "Obstetrics & Gynecology" contains two articles and an editorial, "The Truth About Inherited Thrombophilias and Pregnancy" discouraging random testing for thrombophilias, and when found, treatment with anticoagulants.
One study shows that although the prothrombin gene mutation results in an increased risk for the development of certain pregnancy complications in asymptomatic women, another thrombophilia, MTHFR, may actually protect against those complications. Their overall conclusion was that the majority of asymptomatic women who carry an inherited thrombophilia mutation have a successful pregnancy outcome. The other study showed no association between the prothrombin G20210A mutation and pre-eclampsia, premature separation of the placenta or small-for-gestational age babies in a low-risk group of women. These findings raised the question of the need for screening asymptomatic women for this mutation.
Based on these studies and others, Dr. D. Ware Branch wrote an editorial expressing concern that doctors are prescribing heparin and other anticoagulants too frequenlly after testing women who had almost any adverse pregnancy experience. The enthusiasm for using heparin and its derivatives comes from success in heparin treatment of antiphospholipid syndrome in pregnancy. He believes that a primary cause of an adverse pregnancy outcome may be inflammation, not thrombosis which would not be helped by anticoagulants. Using heparin and related drugs can lead to serious complications.
Regarding this question, infertility specialists deal mostly with patients who have experienced recurrent early pregnancy and Dr. Branch points out that two prospective trials show no improvement in live birth rates using low molecular weight heparin in women with antiphoispholipid antibodies and recurrent miscarriage. Years ago there was a great deal of enthusiasm for testing women with recurrent miscarriage and other pregnancy complications for thrombophilias and antiphospholipids and, when found, treating with heparin or one of its derivatives. Now the tide seems to be turning against even testing. Definitive multi-center studies are needed to determine "The Truth."