Miscarriage
Spontaneous abortion, commonly called a miscarriage, is the most common complication associated with pregnancy. It has been estimated that approximately 50-60% of human conceptions (fertilized oocytes) fail to achieve clinical viability and are lost before the first missed menstrual period. Approximately 12 to 15 percent of clinically recognized pregnancies (a gestational sac in the uterus) are lost within the first 12 weeks of pregnancy (first trimester loss).
Chromosomal abnormalities are responsible for approximately 50 percent of first trimester pregnancy losses. Of the chromosomal abnormalities, the majority are autosomal trisomies (22.3 %), followed by monosomy X [8.6 %], triploidy [7.7 %], and tetraploidy [2.6 %].
The chances for a viable birth after one miscarriage are approximately 76 percent. After two and three miscarriages the chances for a live birth are 70 and 65 percent, respectively. When one has experienced four miscarriages, a live birth can be anticipated in approximately 60% of these pregnancies.
