Recurrent Pregnancy Loss

Abstract

Normal human reproduction is an inefficient process with only 22.8% of conceptive matings resulting in live birth (Fig. 1) (1,2). Miscarriages are the most common complication of pregnancy, affecting 15% of women (3). Loss of pregnancy is a physically and emotionally challenging ordeal. When pregnancy loss is repetitive, these feelings are magnified and the result is a distressing and frustrating problem for both the patients and the physicians. Recurrent pregnancy losses can occur early or late in the pregnancy. Early pregnancy losses are losses of embryos during the first trimester of pregnancy and have been termed abortions or miscarriages. Although most miscarriages are sporadic and not repetitive, there is a subset of couples that suffer recurrent miscarriage. Although the risk of miscarriage increases with maternal age, overall 15% of pregnancies miscarry. Approximately 13% of all recognized first pregnancies are lost. The risk of a second consecutive miscarriage is only slightly increased to 17%. However, the risk of miscarriage after two consecutive pregnancy losses rises to between 35 and 40% and continues to rise with each subsequent miscarriage (4). As many as 5% of all couples conceiving experience two consecutive miscarriages and 2% have three or more consecutive losses. Late pregnancy losses are losses of fetuses after the first trimester of pregnancy. Late pregnancy losses occur far less frequently than early pregnancy losses and comprise only 1% of pregnancies. Late pregnancy losses are usually associated with incompetent cervix, premature rupture of membranes, preterm labor, intrauterine growth retardation, or placental abruption.