Testing for Causes of Recurrent Miscarriages

Patient about to have blood drawn
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After having a miscarriage, most women want to know why it happened and whether anything could have prevented it. Usually, the cause was a random genetic problem in the developing baby, and there was nothing that could have prevented it. And as you probably know, the majority of women who have one miscarriage go on to have an uneventful next pregnancy.

But with two, three or more miscarriages in a row, the chances are lower that the problem is random chromosomal issues — and it makes sense to see a doctor to check for potentially treatable causes of multiple miscarriages. There aren't always answers, but about half the time the tests will reveal a reason why the miscarriages might be happening – and a treatment that might boost the odds of a successful subsequent pregnancy.

What follows is a list of the most common tests that doctors use for women with recurrent miscarriages. Note that the field of recurrent miscarriage treatment is fraught with controversy — the jury is still out on some possible miscarriage causes, and many common treatments for recurrent miscarriages are not proven to work.

Note: The exact tests that your practitioner runs may be different from this list.

Testing for Problems with the Uterus

  • Hysterosalpingogram (HSG)
    • During this imaging test, a dye is injected into the uterus and an X-ray is taken; it looks primarily at whether the fallopian tubes are open, as well as for an abnormal shape of the uterus that might cause problems in pregnancy.
  • Hysteroscopy
    • A hysteroscopy involves inserting a thin telescope into the uterus to get the most accurate picture. A doctor may be able to repair minor problems during the test.
  • Transvaginal Ultrasound
    • Doctors can also use ultrasound to check for uterine, ovarian, and endometrial problems that could be contributing to recurrent miscarriages.
  • Endometrial Biopsy
    • Rarely, doctors remove a small piece of the endometrium (the lining of the uterus) to help diagnose conditions that may be interfering with conception or pregnancy.

Blood Tests

  • Lupus Anticoagulant Antibodies
    • Lupus anticoagulant antibodies are one of the markers for antiphospholipid syndrome, which seems to increase some women's chances of recurrent miscarriage.
  • Anticardiolipin Antibodies
    • Anticardiolipin antibodies are another marker for antiphospholipid syndrome.
  • PT and aPTT
    • PT stands for Prothrombin Time, and it is a test to see how fast the blood clots. aPTT stands for Activated Partial Thromboplastin Time, and it is another blood clotting test. Abnormal results on either might be associated with hereditary thrombophilias (blood clotting disorders like antiphospholipid syndrome).
  • MTHFR Gene Mutation
    • Mutations in the MTHFR gene can impair the body's ability to absorb folic acid. A few studies have associated MTHFR gene mutations with an increased risk of miscarriages, but most have found the gene not to be a major factor in causing miscarriages.
  • Protein C, Factor V Leiden, Protein S deficiency, Prothrombin gene mutation and Antithrombin III deficiency
    • These are the hereditary thrombophilias that seem to be linked to miscarriages after 10 weeks. Some doctors test for these and others do not.
  • Thyroid Panel
    • Some evidence suggests that hypothyroidism may increase the risk of second-trimester miscarriage, but the evidence is not conclusive. Some practitioners routinely test women for thyroid issues and others do not.
  • Progesterone
    • The link between progesterone and miscarriages is a matter of hot debate. When doctors do test progesterone, the test usually involves a blood draw a week after ovulation, or on day 21 of a 28-day cycle.
    • Especially in women over 35, doctors may also test for levels of other hormones, such as follicle-stimulating hormone (FSH), anti-Mullerian hormone (AMH), and luteinizing hormone (LH). These hormones are all related to ovulation.
  • Karyotyping of the Parents
    • This test would be performed on both parents and looks for problems in the genetic structure that might boost pregnancy loss risks, such as balanced translocation.

Other Tests

  • Fetal Tissue Karyotyping
    • If a woman had a D&C for her most recent miscarriage, the doctor may want to order a chromosomal test of the tissue in order to rule out chromosomal abnormalities as a cause of the miscarriages.

You may have mixed feelings about seeking testing. Recurrent miscarriages can put you in the strange position of actually wanting to find something wrong with you because putting a name to the problem and having a potential treatment might make the idea of the next pregnancy seem a little less scary. Some women even feel scared to proceed with testing because they’re afraid they won’t find answers.

If you feel that way, it’s understandable, but try to remember that even if you don’t get answers, you should feel some reassurance that at least you can try again knowing that you do not have a known medical problem to get in the way of your having a successful pregnancy. Even though statistics may not be reassuring, studies indicate that 70% of couples who have recurrent miscarriages without a known cause do eventually go on to have a successful pregnancy. So the odds are still high that someday this ordeal that you are going through right now will just be a bad memory.

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Article Sources
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  5. Barber JC, Cockwell AE, Grant E, Williams S, Dunn R, Ogilvie CM. Is karyotyping couples experiencing recurrent miscarriage worth the cost?. BJOG. 2010;117(7):885-8. doi:10.1111/j.1471-0528.2010.02566.x

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Additional Reading
  • American College of Obstetricians and Gynecologists (ACOG), "Management of recurrent early pregnancy loss." Feb. 2001. ACOG
  • Brigham, S.A., C. Conlon, and R.G. Farquharson, “A longitudinal study of pregnancy outcome following an idiopathic recurrent miscarriage.” Nov. 1999. Human Reproduction 14:2868-2871.
  • Johnson, Kate. "Recurrent miscarriage tied to insulin resistance: Check fasting insulin levels." OB/GYN News 15 Jan 2002.
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