Tissue is also expelled. In a missed abortion, the fetus has died or did not develop. The pregnancy tissues have not been expelled from the uterus. With this type of miscarriage again there is little sign of what is happening until it has already happened. An infected abortion, or a septic abortion, is when a serious infection occurs in the fetal material before, during, or after the miscarriage.
Miscarriages are an unexplained thing.
It has not been reasearched as well as some would like, but hopefully the future will bring more knowledge in how to prevent this. The majority of miscarriges happen within the first 12 weeks of pregnancy. The most common age factor in a miscarriage is women older than 35. Another common miscarriage is women carrying mulitple fetuses. Miscarriage rates about double when a women turns 40.