We have the technology to be increasingly aware of early miscarriage or what is medically termed spontaneous abortion. There was a time, not all that long ago, when women were told not to call the doctor before they missed three consecutive periods. And as a result there were alot of miscarriages that went undetected. Women thought that they were irregular and just having a "bad" period. Now with early detection: ultrasound and serial human chorionic hormone blood tests, home pregnancy urine tests and ovulation predictor kits, we know a whole lot more than we used to. We know that pregnancy is fragile and that 25% of all conceptions terminate in early spontaneous abortion, miscarriage.
The reason that these early miscarriages occur is often answered by testing miscarriage tissue for chromosomal abnormalities. The first step ( as opposed to sperm counts and progesterone levels ) should be examination of products of conception for random chromosomal errors. A woman who has lost 2-3 pregnancies before ten weeks gestation ( counted from the first day of the last menstrual cycle ) is considered a habitual aborter and these women must be notified ( as all others )that it is very important to keep and provide their providers with any clots, tissues or debris from the bleeding episode. Use a cup or a baggie, use anything ( it need not be sterile )to bring products of conception to the doctor for karyotyping by a genetics laboratory. A kayotpye is that picture of the chromosomes that we have all seen in biology books. Research shows that 70% of spontaneous abortions that occur prior to six weeks gestation are due to numeric chromosomal errors, like trisomy, monosomy or polyploidy. Miscarriages occuring between six and ten weeks gestation are associated with chromosomal errors 50% of the time. And then, after ten weeks, it is a chromosomal error only 5% of the time.
So if you want to know for sure, why you have miscarried, maybe again and again, SAVE PRODUCTS OF CONCEPTION ( BLOOD, CLOTS, TISSUE, ANYTHING ) and bring it to the doctor for testing. If the testing shows that it isn't chromosomal then there are lots of other tests that can be done to try to figure it out. But unless you are proactive and save products and insist on testing, it won't be done. Genetic tests are done with d&c ( dilitation and curettage ) especially if you make sure to ask. And then, you and your provider can take it from there.