A very small number of couples with repeat miscarriages—and we are only taking of about 3 to 5 percent of those who have had recurrent miscarriage—may in fact have an abnormality in their chromosomes, in either partner, which dose not affect their own lives but may affect the fetus. For example, an abnormality in your chromosomes may not be reflected in your appearance, but if it affects the number of chromosomes in your egg cell, then it could cause a problem when meiosis takes place.
A patient of mine had a certain rare malposition of her chromosomes. She was very upset to learn about this and needed a lot of reassurance that she was absolutely normal—not a freak. However, the only way they could try for a normal baby, unfortunately, was just to keep trying. They would possibly have to put up with repeated miscarriages until one conception managed to override the problem. Their chances of having a normal healthy baby, however, were good. The sad part is that in such a rare case, nothing can be done to prevent it or treat it. At this stage, there is no way we can alter the body’s chromosomal makeup. Some day in the future, through work that is now being done with in vitro programs, genetic information will be extracted from a fertilized egg and preventive treatment given.
Similarly, another patient who was happily looking forward to her first baby discovered very sadly after amniocentesis that she, at the age of forty-three, had a polysomy 47XXX. We had to tell her that although such children are born looking normal, they are usually mentally abnormal. It was a terrible decision for her to make, but she decided to terminate the pregnancy. Again, she stands a good chance of a normal pregnancy the next time.
Translocation is a term you might come across in a discussion of chromosomes. With this condition, there is the correct number of chromosomes but the pieces are joined up incorrectly. You may have inherited this problem from one of your parents, but in your own conception it was balanced out. If a similar problem affects your partner, then it could be a cause of recurrent miscarriages for you as a couple. It is a rare condition, but one that should be tested for.
Most parents are very aware of a common birth defect, Down’s syndrome, or mongolism, which is caused by an extra chromosome, usually no.21, giving a count of 47, rather than 46. The condition is also known as trisomy 21. in the live-born baby, Down’s syndrome results in the characteristic skin folds at the inner corner of the eyes, a large protruding tongue, small hands and fingers, as well as defects of the heart, eyes, ears, and various degrees of mental retardation. Many of these defective embryos, however, do miscarry in early pregnancy.
