Factor V Leiden and Miscarriage

Miscarriage risk only increases 1% with Factor V Leiden

Research published this week in PLoS Medicine finds that pregnant women with an inherited condition that makes them more likely to form blood clots only face a small increase in the risk that they might have a miscarriage or stillbirth. The researchers performed a systematic review of studies investigating placenta-related problems in pregnancy and women with thrombophilia and found that the increase in the risk of pregnancy loss in women with Factor V leiden was only 1%, whilst there was no significant increase in the risk to women with prothrombin gene mutation. The findings also show no association between inherited thrombophilia and other placenta-related pregnancy problems.

http://www.sciencedaily.com/releases/2010/06/100615191645.htm

Early miscarriage not associated with activated protein C resistance or factor V Leiden

Blood samples collected from 907 pregnant women were tested. Sixteen percent of the study group had an Activated Protein C Resistance phenotype. Factor V Leiden, FV Cambridge, and haplotype (H) R2 alleles were identified in this group. Adverse pregnancy outcomes were found at a frequency of 35% in the group with Activated Protein C Resistance based on Classic Coatest test only and at 45% in the group with Activated Protein C Resistance based on the Modified Coatest test. Forty-eight percent of subjects with Factor V Leiden had adverse outcomes while in the group of subjects with no Factor V Leiden, adverse outcomes occurred at a frequency of 37%. Adverse outcomes including early miscarriage, preeclampsia and intrauterine growth restriction were not significantly more frequent in subjects with Activated Protein C Resistance compared to normal pregnant women, however pregnancy induced hypertension was found to be associated with Factor V Leiden in our study group.

http://www.ncbi.nlm.nih.gov/pubmed/20214832

13.9% of late miscarriages are associated with Factor V Leiden

In the subgroup analysis of women with at least one late miscarriage, the prevalences of the ER-alpha IVS1-401 T allele (T/T vs. C/C, odds ratio: 2.85; T/T + C/T vs. C/C, odds ratio: 2.28) and of heterozygous factor V Leiden (odds ratio = 3.2) were significantly higher among women with late miscarriage than among healthy women. Carriers of both risk determinants have an at-least additive increase in risk for late miscarriages (odds ratio, 7.0). The population of all late miscarriages that would be attributable to the genetic variants (population attributable risk) was 13.9% for factor V Leiden and 49.2% for the ER-alpha IVS1-401 T allele.

http://www.ncbi.nlm.nih.gov/pubmed/16753154

Factor V Leiden increases risk of stillbirth by up to 330%

Factor V Leiden was associated with 3.8-fold risk for unexplained stillbirth, 3.9-fold risk for unexplained late stillbirth (> or =28weeks of gestation), and 10.8-fold risk for unexplained stillbirth with placental lesions. The same figures for singleton pregnancies were 3.1-fold, 4.3-fold, and 10.6-fold. Slightly increased risk associated with blood group O was not statistically significant. We found a trend for increased risk in advanced maternal age and smoking during pregnancy. High pre-pregnancy BMI was not associated with increased risk, nor was low educational level or first pregnancy.

http://www.ncbi.nlm.nih.gov/pubmed/19828176

Factor V Leiden is associated with repeat miscarriage

The Factor V Leiden G1691 mutation was present in 6 of 33 women (18%) with PCOS-repeat miscarriage and in 3 of 16 women with repeat miscarriage without PCOS (19%) versus 2 of 116 (1.7%) healthy female controls. The 33 PCOS-repeat miscarriage cases also differed from the 44 female controls for high PAI-Fx, 38% versus 8%. The thrombophilic G1691A Factor V Leiden mutation is associated with repeat miscarriage in women with and without PCOS; hypofibrinolysis (high PAI-Fx) is also associated with repeat miscarriage in women with PCOS.