Testing for Causes of Recurrent Miscarriages

After having a miscarriage, most people 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 nothing could have stopped it. And the majority of people 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. So at this point, 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 why the miscarriages might be happening. Treatment might boost the odds of a successful subsequent pregnancy.

Uterine Tests

Sometimes problems with the uterus, such as endometriosis or an abnormally shaped uterus, may lead to recurrent miscarriages. Tests that look at problems with the uterus include:

• Hysterosalpingogram (HSG): A dye is injected into the uterus. An X-ray is taken to look at whether the fallopian tubes are open and for an abnormal shape of the uterus that might cause problems in pregnancy.
• Hysteroscopy: A thin telescope is inserted into the uterus to view and repair minor problems of the uterus.
• Transvaginal ultrasound: An ultrasound checks for uterine, ovarian, and endometrial problems that could be contributing to recurrent miscarriages.
• Endometrial biopsy: A small piece of the endometrium (the lining of the uterus) is removed to help diagnose conditions that interfere with conception or pregnancy.

Blood Tests

Blood tests are a non-invasive way to evaluate evidence of underlying health conditions, hormonal imbalances, or gene mutations that could contribute to recurrent miscarriages. Blood might be tested for:

• Lupus anticoagulant antibodies: One of the markers for antiphospholipid syndrome
• Anticardiolipin antibodies: Another marker for antiphospholipid syndrome
• MTHFR gene mutation: This mutation can impair the body's ability to absorb folic acid and may be linked to an increased risk of miscarriages
• Thrombophilias: PT (prothrombin time), aPTT (activated partial thromboplastin time), protein C, factor V Leiden, protein S deficiency, prothrombin gene mutation, and antithrombin III deficiency can all be linked with recurrent miscarriages
• Thyroid panel: Hypothyroidism may increase the risk of second-trimester miscarriage (although the evidence is not conclusive)
• Progesterone: Tested a week after ovulation or on day 21 of a 28-day cycle to check for abnormal levels
• Other hormones: Especially in people over 35, test for levels of follicle-stimulating hormone (FSH), anti-Mullerian hormone (AMH), and luteinizing hormone (LH)
• Karyotyping of the parents: Performed on both parents to look for problems in the genetic structure that might raise pregnancy loss risks, such as balanced translocation

Other Tests

Other tests, such as fetal tissue karyotyping, might be done if you had a D&C for your most recent miscarriage. This is a chromosomal test of the tissue to rule out chromosomal abnormalities as a cause of miscarriages.

A Word From Verywell

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 a diagnosis and potential treatment might make the idea of the next pregnancy seem a little less scary. But, on the other hand, you may feel scared to proceed with testing because you're afraid you won’t find answers.

If you feel that way, it’s understandable. However, 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.