Wednesday, July 04, 2007

Repeated Miscarriage

If you've miscarried more than twice in a row prior to 20 weeks, you're prone to what's known in lay terminology as "repeated miscarriages." (Clinical terms for this are habitual abortion or recurrent fetal loss.) This is considered a form of infertility, but in my opinion, labeling "repeated miscarriage" as "infertility" -- meaning inability to conceive -- is inaccurate! Repeated miscarriages have to do with an inability to complete the pregnancy. This is truly a different kind of problem than not becoming pregnant to begin with. Nevertheless, women who suffer from repeated miscarriages will need to undergo a battery of tests under the care of an "infertility specialist" -- a reproductive endocrinologist/gynecologist.

If you have no history of full-term pregnancies, then you suffer from primary repeated miscarriage. If you've had one child or even a stillbirth at term, you have secondary repeated miscarriage. Tests include an endometrial biopsy and a hysterosalpingogram (where a dye is injected into your fallopian tubes, checking not for blockages but for uterine abnormalities). In most cases of repeated miscarriage, the cause is found; in a few cases, nothing is ever discovered as the definitive cause. Women who have suffered as many as six or seven miscarriages, however, can go on to have a successful pregnancy.

One cause of miscarriage has to do with untreated bacterial infections, such as mycoplasma. If left untreated, mycoplasma can lead to an inflamed endometrium (endometritis), which can interfere with the embryo implanting. Another cause of some miscarriages is the effect of certain toxins that include anesthetic gases (that's why the consent form for a surgical procedure tells you about a risk of miscarriage). Exposure to lead and mercury are also causes, but usually these toxins are discovered before a second miscarriage.

Other causes cited for repeated miscarriage include genetic problems, structural problems involving the uterus or cervix (such as an incompetent cervix), luteal phase defects (discussed below), diabetes, and thyroid disease (if it's not treated promptly).

Luteal Phase Defects

Some doctors believe that a significant number of repeated first-trimester miscarriages are caused by a progesterone deficiency; others don't subscribe to this theory at all, even though there is strong evidence to support it.

Once your ovary spits out a follicle, the empty shell turns into a corpus luteum. If you imagine a single pea pod, the pea is the follicle, which will become the egg, while the pod is what will turn into a corpus luteum, which should produce progesterone once the embryo implants. Human chorionic gonadotropin (hCG), secreted from the developing placenta, stimulates the corpus luteum to make progesterone. As the placenta matures at about seven weeks, it takes over progesterone production. However, if the corpus luteum is not functioning properly and is therefore not making adequate amounts of progesterone, you will miscarry. Hormonal tests that include an endometrial biopsy will confirm whether you have this type of luteal phase defect.

The treatment is simple, involving daily dosages of natural progesterone in vaginal suppository form during the luteal phase of the menstrual cycle. Then, if conception occurs, progesterone suppositories are prescribed daily for the first 12 weeks of pregnancy. The average dosage is 50 milligrams of progesterone twice a day, but some women will be given a stronger prescription of 100 milligrams of progesterone taken two or even three times a day. Some doctors will also prescribe clomiphene citrate prior to conception, which will increase the amount of progesterone throughout the early stages of pregnancy. The progesterone supposotories are given once the pregnancy is established. Clomiphene citrate is also associated with lower incidences of miscarriage. Progesterone supplements are successful about 80% of the time in averting another miscarriage.

Repeated miscarriages can be caused by a scrambled LH (luteinizing hormone) surge. Normally, the LH surge occurs just prior to ovulation, but in some women, the surge can take place at the beginning of the cycle -- (common in women suffering from polycystic ovarian syndrome (PCO). The treatment is to be placed on a urofollitropin (pure FSH) or a GnRH analogue. This is still in the experimental stages, but studies show that this treatment is promising.

Immunological Factors

Between 20% and 25% of all repeated miscarriages are due to immunological problems. The woman's immune system causes her body to reject the fetus as foreign tissue for the same reason transplant patients reject organs. In this case, the mother's body is rejecting the father's antigens (a.k.a. paternal antigens) that make up the developing fetus. This problem can often be solved through either passive immunization (injecting the mother with the father's antibodies prior to conception) or active immunization (injecting white blood cells from both the mother and father into the mother's body before conception). In either case, the point of this treatment is for the mother's body to get used to his cells so that they recognize the fetus later on as friendly. Some clinics report about a 70% success rate using this method. Usually, giving the mother only paternal white blood cells yields the best results.

Phospholipid Antibodies and Recurrent Miscarriage

About 15% of immunological causes involve women who produce antibodies that indirectly cause clotting in blood vessels that lead to the developing fetus. The fetus is deprived of nutrients and dies in utero, which triggers a miscarriage. The good news is that there is now treatment for this condition, with the aid of aspirin, heparin (an anticoagulant), and corticosteroids.

If your doctor recommends daily aspirin therapy, you can start with a very low dose of baby aspirin (78-81 milligrams per day). There are very few side effects with this dosage. Women who take adult aspirin or high dosages of aspirin have complained of side effects such as nausea, heartburn, upset stomach, decreased appetite, and even microscopic amounts of blood in their stools. (Blood in the stools could be caused by hemorrhoids or may be evidence that you are having bleeding from your gastrointestinal tract.)

Experts also recommend that you avoid the following foods when you're taking daily low- dose aspirin: Curry powder, paprika, licorice, prunes, raisins, gherkins, tea, and other than the occasional use of nonabsorbable antacids (Maalox, Rolaids). All of these are foods that can irritate your gastrointestinal tract.

Heparin is an anticoagulant often prescribed to prevent blood clotting problems. It's administered by subcutaneous (under the skin) injection. Since some women have allergic reactions to it, a trial dose of 1,000 IU of heparin should be done as a skin test first. You should discuss all the short- and long-term risks associated with heparin during pregnancy; it is not free from side effects and has also been associated with osteoporosis (bone loss). Because of this, many doctors will prescribe a calcium supplement along with heparin during pregnancy. You should also ask what conditions may prevent you from taking heparin.

Make sure you notify all your doctors if you're taking heparin (you should carry an ID card stating so, in case of an emergency or accident). You should also stay alert to warning symptoms, such as:

* Nose bleeds
* Blood in the toilet, your urine or stool
* Uncontrolled or excessive bleeding lasting longer than 15 minutes
* Unusual bruising not at the injection site

Less Common Causes

About 15% of all repeated miscarriages are caused by a uterine structural problem, where tissue interferes with fetal development. This is usually correctable with surgery, depending on the severity of the defect. About 3% of repeated miscarriages are caused by an "incompetent cervix." This problem leads to second-trimester miscarriages and can be prevented by stitching up the cervix. While about 5% of repeated miscarriages (as opposed to single episodes) are caused by chromosomal abnormalities, this is not a "correctable" problem, but a "luck of the draw" cause. It is also the cause of most first-time miscarriages, which occur once in six normal pregnancies. In this case, couples need to keep trying until they strike a good mix of chromosomes.

How Many Miscarriages in a Row Should We Endure?

After two miscarriages, you should stop trying and go for diagnostic tests to see why you're miscarrying. Often, the reasons are unknown and you'll go on to have a successful third pregnancy. Even after two miscarriages, there's a 70% chance that your third pregnancy will be fine. But if a reason does turn up, it may be easy to fix, and finding the cause at this point will prevent further trauma to you. Keep in mind, though, that one or two miscarriages do not make you infertile and are generally not precursors to future problems.

"Copyright © 1998 by M. Sara Rosenthal. From The Fertility Sourcebook, by arrangement with The RGA Publishing Group."

No comments: