Miscarriage, the commonest complication of pregnancy, is the spontaneous loss of a pregnancy before the fetus has reached viability. The term therefore includes all pregnancy losses from the time of conception until 24 weeks of gestation. Recurrent miscarriage, ... Miscarriage, the commonest complication of pregnancy, is the spontaneous loss of a pregnancy before the fetus has reached viability. The term therefore includes all pregnancy losses from the time of conception until 24 weeks of gestation. Recurrent miscarriage, defined as 3 or more consecutive pregnancy losses, affects about 1% of couples; when defined as 2 or more losses, the scale of the problem increases to 5% of all couples trying to conceive (summary by Rai and Regan, 2006). Pregnancy losses have traditionally been designated 'spontaneous abortions' if they occur before 20 weeks' gestation and 'stillbirths' if they occur after 20 weeks. Subtypes of spontaneous abortions can be further distinguished on the basis of embryonic development and include anembryonic loss in the first 5 weeks after conception (so-called 'blighted ovum'), embryonic loss from 6 to 9 weeks' gestation, and fetal loss from 10 weeks' gestation through the remainder of the pregnancy. These distinctions are important because the causes of pregnancy loss vary over gestational ages, with anembryonic losses being more likely to be associated with chromosomal abnormalities, for example. Possible etiologies for recurrent pregnancy loss include uterine anatomic abnormalities, cytogenetic abnormalities in the parents or fetus, single gene disorders, thrombophilic conditions, and immunologic or endocrine factors as well as environmental or infectious agents (summary by Warren and Silver, 2008).
In 70 German patients with recurrent pregnancy loss (RPRGL) who were known to carry neither factor V Leiden (612309.0001) nor the 20210G-A prothrombin mutation (176930.0009), Bogdanova et al. (2007) analyzed the gene encoding the placental anticoagulant protein annexin ... In 70 German patients with recurrent pregnancy loss (RPRGL) who were known to carry neither factor V Leiden (612309.0001) nor the 20210G-A prothrombin mutation (176930.0009), Bogdanova et al. (2007) analyzed the gene encoding the placental anticoagulant protein annexin A5 (ANXA5; 131230). They identified 4 consecutive nucleotide substitutions in the promoter region that were transmitted as a joint haplotype that they designated 'M2' (131230.0001). Carriers of the M2 haplotype had a greater than 2-fold higher risk of RPRGL than noncarriers (odds ratio, 2.42) when using unselected controls; when compared to women with successful pregnancies and no previous history of pregnancy loss, carriers had an almost 4-fold higher risk of RPRGL (odds ratio, 3.88).