why are miscarriages more likely to occur during the first trimester
In those under the age of 35 the risk is about 10% while it is about 45% in those over the age of 40. Risk begins to increase around the age of 30. About 80% of miscarriages occur in the first 12 weeks of pregnancy (the first trimester). The underlying cause in about half of cases involves chromosomal abnormalities. Other conditions that can produce similar symptoms include an ectopic pregnancy and implantation bleeding.