For an increasing number of couples, the joy of achieving pregnancy results in a devastating situation in which a miscarriage occurs with the loss of a pregnancy, usually in the first trimester. Miscarriages occur in about 1/6 (one-sixth) of all pregnancies, and many of them are due to a disarrangement of chromosomes during cell division. This usually doesn't happen two times. However, some patients are plagued by repeated miscarriages. In these cases, miscarriages may be due to hormonal imbalances, abnormalities of the uterus, or genetic abnormalities. Modern technology can correct most of these problems. Endometriosis (IN-doe-me-tree-OH-sis) is a condition where uterine tissue grows outside the uterus and has also been associated with miscarriage. This condition can be detected and cured so that it doesn't interfere with pregnancy. In many couples there's an immunologic cause for multiple miscarriages. A simple blood test can be done to look for abnormal antibodies, which attack the early placenta as it tries to develop its root system into the wall of the uterus. For most causes of miscarriage, there's a cure or a corrective procedure available.