A missed abortion—you will seldom hear it referred to as a missed miscarriage, maybe simply because of the clumsy alliteration—refers to a fetus that miscarried, or died, but that has not been expelled. The fetal and placental tissue is still inside you. If this dose happen, it is advisable to have a D&C  without too much delay. First, if necessary, the fetal material can be taken straight to the hospital, or directed to the correct lab, for chromosomal testing and pathology. The fresher the tissue, the more likely you are to receive usable results; it can be difficult for the laboratory to grow the chromosomes if the tissue has been dead too long.

Second, you will not have to suffer the potentially traumatic experience of knowing you have a dead baby inside of you. Third, you will avoid a remote risk of infection getting into the uterus and harming you. Fourth, you will also avoid the risk of the fetus aborting itself during the night, with the consequent emergency rush to the hospital. Lastly, there is the very remote risk of your developing a clotting disorder if a dead fetus is retained beyond about six weeks. This is especially so with a more advanced fetal death, rather than in very early pregnancy.