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I just had a miscarriage. Will it happen again?

“Today” contributor Dr. Judith Reichman discusses the causes of a miscarriage and describes who could be at greater risk.

Q: I’m in my late 20s, and I just had a miscarriage in my seventh week of pregnancy. I really want a baby, but I’m scared this might happen again. Should I be worried?

A: Having had one miscarriage does not put you at increased risk the next time you become pregnant. Women who have recurrent pregnancy loss  (RPL), defined as two or more miscarriages, do have a higher risk of subsequent pregnancy loss, but you certainly don’t fall into that category.

About 10 percent to 15 percent of known (and likely many more unknown) pregnancies miscarry, most in the first trimester. In a way, that’s an amazingly small number, considering the very complicated process of getting a pregnancy right: sperm meeting and penetrating the egg; half of the chromosomes from each conjoining without missing a piece or mixing up the pieces; appropriate cell division and the right hormones being in place to allow for implantation and fetal growth; and to support all this, a sterile, non-toxic, expandable housing unit capable of providing nourishment.

In many cases, miscarriage is really the inability of the fetus to develop in a way that would enable it to live and thrive. The most common cause for miscarriage is chromosomal abnormalities. More than half of miscarriages in the first 13 weeks are due to an inappropriate number or structure of chromosomes that had to divide, match and fit into the nucleus of the dividing cells that ultimately form the embryo.

Lack of chromosomal “perfection” is usually not due to you or your partner, but is instead purely random.

However, if a couple comes in with history of RPL, their doctor may order genetic testing on their blood to see if a “translocation” is occurring. This means that the right number of chromosomes is present, but they have been inserted in the wrong places, and during separation and division either a piece is missing or an extra piece is passed along.

Other known causes of miscarriage include:

  • Uterine problems: These may due to the improper development of a woman’s uterus from the time of birth. (The uterus originally develops in two halves, and if they don’t completely merge a wall or septum can remain, deforming the uterine cavity.) Another, unfortunately common source of uterine-caused miscarriage is the development of fibroids which can prevent fetal growth or cause premature contractions.  
  • Cervical problems: If the cervix is traumatized or foreshortened by previous deliveries, surgery or DES exposure, it can become “incompetent,” allowing the membranes containing the fluid that surrounds the developing pregnancy to bulge downward and rupture. This in turn causes late miscarriage or premature delivery.
  • Hormonal factors: It is felt that 15 percent to 50 percent of RPLs are hormonally related and due to inadequate production of progesterone, the hormone that is needed to maintain the lining of the uterus.
    Women with very irregular cycles, combined with an increase in male hormone and overproduction of insulin (a condition known as polycystic ovary syndrome) are more likely to have problems getting pregnant and also have a higher rate of miscarriage.
    Hormones from other glands (such as the thyroid) can also affect a pregnancy.
  • Medical conditions: Women with diabetes have a two-to-threefold risk of miscarriage.  Lupus and other autoimmune disorders (in which a woman produces antibodies against her own tissues and that of the fetus) also increase the risk of rejection and pregnancy loss.

In some cases, it’s not the “wrong” antibodies that are the problem, but instead the lack of the “right” ones. A mother’s placenta must make anti-rejection antibodies. In certain immunologic conditions, the mother’s system is too similar to that of the father’s and those antibodies do not form. Treatment for this is still controversial, but doctors often advise using aspirin and in some cases even immunizing the mother by injecting her with white blood cells from the father.

I don’t want to belittle your pregnancy loss by saying it has only happened once. No matter how early or late it occurs, a miscarriage can be extremely traumatic, and it may take awhile to feel you have “healed” from this event.

However, if you’re young and healthy, have had normal periods and didn’t have trouble conceiving, my advice is to wait to get the next two or three periods and then try again.

If at that point you have another miscarriage, you should have a medical workup. This should include blood tests to check for abnormalities of hormone production and to assess your immune system. Chromosomal testing of you and your partner (or a sample of the miscarried tissue) should be done, especially if there is a third miscarriage.  Additional tests include cultures to detect infection of the cervix and uterus (such as mycoplasm and ureaplasm and chlamydia); a pelvic ultrasound; an X-ray with dye injected into the uterine lining and fallopian tubes (hysterosalpingogram); or a procedure in which a scope is inserted into the lining (hysteroscopy) to check for malformations or fibroids; and a complete physical.

Dr. Reichman’s Bottom Line: If you’ve had a single miscarriage, you are at no greater risk for having another one than a woman who’s never had a failed pregnancy. However, even with recurrent miscarriages, you still have a better than 75 percent chance of one day carrying a baby to term. Talk to your doctor if you’ve had more than one miscarriage. Appropriate tests should be done and you may need special care as the pregnancy develops.

Dr. Judith Reichman, the “Today” show's medical contributor on women's health, has practiced obstetrics and gynecology for more than 20 years. You will find many answers to your questions in her latest book, "Slow Your Clock Down: The Complete Guide to a Healthy, Younger You," which is now available in paperback. It is published by William Morrow, a division of .