Spontaneous abortion before the 16th week of pregnancy. The birth of an immature baby incapable of sustaining life after the 16th week is sometimes also inaccurately called a miscarriage; in a true miscarriage the foetus, the placenta (which is still forming) and associated membranes are all expelled at once. After the 16th week, foetus and placenta are usually expelled separately, as in a normal birth. About 10 percent of all pregnancies end in miscarriage. Even after several miscarriages the cause almost always lies with the foetus, very rarely with the mother. The notion that sexual intercourse during pregnancy can cause a miscarriage is unfounded for the same reason. After a miscarriage it is advisable to keep the expelled tissues, in a glass of water for example, for medical examination. Such an examination