Recurrent Pregnancy Loss Treatment
Approximately one in every six pregnancies ends in miscarriage. The causes of miscarriage can be divided into several large categories: hormonal disorders such as an underactive thyroid, metabolic problems such as diabetes, abnormalities of the uterine shape, sexually transmitted infections such as chlamydia, genetic causes, immunologic abnormalities such as the presence of anti-phospholipid antibodies, and alterations in blood clotting.
The most common cause of pregnancy loss is due to an embryo possessing an abnormal number of chromosomes – either one too many or one too few. During formation of eggs and sperm, the number of chromosomes each cell possesses is normally halved (from 46 to 23), so that when the egg and sperm join at fertilization, the normal number 46 is restored. Unfortunately, that halving process (termed meiosis), can go wrong. This problem increases with a woman’s age, but not a man’s age, although men with very low sperm counts at any age can have increased numbers of chromosomally abnormal sperm. The majority of embryos possessing an abnormal number of chromosomes are lost in the first trimester of pregnancy, although some babies may be born with an extra chromosome 21 (Down’s syndrome) or missing X chromosome (Turner’s syndrome).
After an egg is released (“ovulation”), the ovary produces progesterone, which helps to create the “fertile bed” in which the embryo grows to establish a normal pregnancy. The level of progesterone is measured during pregnancy to confirm that there is enough of this hormone to support a pregnancy. Another hormone, HCG (human chorionic gonadotropin), is measured at the same time. This hormone is produced by the embryo and stimulates the ovary to produce large amounts of progesterone. In early pregnancy, HCG levels approximately double every two days, and this increase provides a measure of the health of the embryo. If HCG levels do not rise normally when measured over several days, the embryo itself is not healthy. Measuring the levels of both hormones, HCG and progesterone, helps to distinguish cause and effect and determine whether to prescribe additional progesterone, to support the pregnancy.
An abnormally shaped uterus may predispose to miscarriage. The uterus is formed during a woman’s embryonic development from two primitive tubes (the Mullerian ducts) that join together. Sometimes this joining is incomplete, so that the uterus has an abnormal shape. This can be corrected by surgery in some cases (as when there is a uterine septum). MRI and 3-D ultrasound scans of the uterus aid in the diagnosis. These congenital (present at birth) abnormalities of the uterus may predispose to miscarriage in the first the trimester, but also are associated with a weakening of the entrance of the uterus, (the cervix), which may open prematurely during the second trimester and lead to pregnancy loss. Monitoring by repeated ultrasound examinations during pregnancy is done to look for this and take action.
Sometimes, a miscarriage itself may lead to future miscarriages. When the uterus does not empty its contents completely after a miscarriage, this may possibly lead to infection, and the need for a subsequent D & C (dilation and curettage). These circumstances predispose to scarring within the uterus, leading to subsequent miscarriage. This scarring needs to be removed before a woman attempts to become pregnant again. Saline sonograms, during which sterile salt water is injected within the uterus while it is studied by ultrasound, can be performed to diagnose the presence of these scars.
Blood tests must also be performed to look for hidden diabetes and abnormal thyroid function, as well as for antibodies to phospholipids that damage the placenta.
Most of the time, having had a miscarriage does not indicate that there will be difficulties in the future. In fact, the likelihood of a second pregnancy loss following a first loss is approximately 20 percent, and even following a subsequent second loss, the odds of a miscarriage in the next pregnancy are about 25 percent. This means that the majority of couples in whom no other cause of miscarriage is found have a good chance of a successful pregnancy in the future. It is important, however, that the couple undergo an evaluation to determine that there is no underlying condition that predisposes them to greater risks of pregnancy loss. Obtaining a chromosome analysis of the tissue passed from the uterus at the time of miscarriage can also be helpful in determining the cause of the pregnancy loss, by confirming whether the chromosomes are abnormal or not. In the latter case, additional studies need to be done, to look for other causes of pregnancy loss.
Contributed by Richard Bronson, M.D.