Recurrent Miscarriage & Pregnancy Loss

Recurrent miscarriage at a glance

• A miscarriage is defined as a pregnancy loss before the 20^th week of pregnancy. Studies have shown that 15 percent of all pregnancies result in a miscarriage, and the risk increases as a woman ages.
• Recurrent pregnancy loss is when a woman has experienced two or more consecutive miscarriages with the same partner.
• The causes of recurrent pregnancy loss are categorized as chromosomal, anatomic, immunologic, infectious, hormonal or genetic, environmental, and unknown.
• The cause of a woman’s pregnancy loss is usually diagnosed through blood tests, imaging studies, ovulation tests and/or cervical cultures.
• A woman should seek treatment from an infertility specialist after experiencing two or more miscarriages, or sooner if there is a known risk of recurrent pregnancy loss.

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Causes of recurrent miscarriage

The American Society for Reproductive Medicine estimates that less than 5% of women will experience recurrent miscarriage of two consecutive miscarriages, with only 1% experiencing three or more consecutive miscarriages. Pregnancy loss can be categorized into seven causes: chromosomal, immunologic, infectious, anatomic, hormonal or other conditions, environmental, and unknown.

Chromosomal pregnancy loss

If either or both parents carry a chromosomal abnormality, it can be passed on to the developing fetus and cause a miscarriage. Although chromosomal abnormalities cannot be treated, chromosomal abnormality testing and genetic counseling can help assess the chances of having a successful pregnancy with the abnormality present.

Chromosomal abnormality testing is usually performed with a blood sample from both the male and the female partners. This test is called a karyotype. The karyotype can determine if either partner has a rearrangement in their genetics that would increase the chances of having a genetically abnormal pregnancy.

Normal genetics in a couple does not always mean that the egg’s, sperm’s or embryo’s genetics are normal. Karyotyping can also be performed on tissue from miscarriages (such as the placenta or the embryo) to see if that particular pregnancy was lost because of a genetic abnormality.

Couples suspected of having losses due to recurrent genetic abnormalities can undergo in vitro fertilization and genetic testing of embryos (preimplantation genetic testing, or PGT). PGT can reduce miscarriage rates by 80 percent.

Immunologic pregnancy loss

Miscarriage may also be caused by the presence of antibodies in a woman’s immune system that affect a pregnancy’s development. The most widely recognized antibodies to cause miscarriage are Lupus anticoagulant and anticardiolipin antibodies.

Although the role that other antibodies play in recurrent pregnancy loss is still controversial, some cases of low-dose aspirin, heparin, or steroid treatment have been shown to improve pregnancy outcomes.

Pregnancy loss may also be caused by blood clotting disorders such as Factor V Leiden, deficiencies of protein C or protein S, Antithrombin III deficiency, and MTHRF mutations.

These clotting disorders increase a woman’s risk for developing dangerous blood clots in the legs and/or lungs, and may increase clotting within the placenta and cause miscarriage. Blood clotting disorders are diagnosed with simple blood tests, and blood-thinning medications can help resolve the problem.

Infectious pregnancy loss

Certain cervical and uterine infections may increase the likelihood of pregnancy loss. These are easily diagnosed with a cervical culture and treated with oral antibiotics. This is a controversial cause of recurrent loss. Testing and/or treatment should be discussed with your physician.

Hormonal or genetic pregnancy loss

Hormonal problems also may increase a woman’s likelihood of miscarriage, such as having a short luteal phase – a condition characterized by having fewer than 12 days between ovulation and the onset of menses. Low progesterone is usually not a cause of recurrent pregnancy loss, but is frequently the result of a poorly developing embryo. It is not wrong to treat women with progesterone, and your physician can help you determine if this treatment is right for you.

Diminished ovarian reserve, in which a woman has a depleted supply of eggs, may also cause pregnancy loss. This is tested through blood work and ultrasound.

Thyroid issues can also affect pregnancy. The thyroid gland secretes several hormones to control how a person’s body processes energy for metabolism, development, growth and body temperature. Problems with the thyroid can inhibit a woman’s body from creating an adequate environment in the womb for a developing pregnancy and can cause a miscarriage. A physician can diagnose thyroid problems with a physical exam, ultrasound or even a CT scan.

Anatomic pregnancy loss

Abnormalities in the uterus or cervix can cause miscarriage. For instance, uterine fibroids, scarring in the uterus (from surgery or previous miscarriage), or the presence of a septum in the uterine cavity make it harder for an embryo to implant in the uterine wall, causing pregnancy loss.

A sonohysterogram – an ultrasound using a saline solution to fill the uterus and improve the visual image – can help diagnose an anatomic problem. Many deformities can be corrected surgically, giving the woman a better chance of having a successful pregnancy.

Some women may also carry anatomic abnormalities caused by being exposed to diethylstilbestrol (DES) while inside their mother’s womb. These abnormalities cannot be corrected, but other treatment options may increase chances of pregnancy.

Environmental exposures

Those who work closely with organic solvents, such as benzene, or toxins such as mercury, or radiation may be at higher risk. This is a rare cause of pregnancy loss.

Unknown pregnancy loss

Up to 50 percent of women with a history of two or more pregnancy losses will not have any identifiable cause. Although no treatment is available for unknown pregnancy loss, many couples still have high chances of having a successful pregnancy following a miscarriage, similar to other couples trying to achieve pregnancy.

When to seek treatment for recurrent miscarriage

An evaluation for recurrent pregnancy loss is usually started after two pregnancy losses. The decision to pursue infertility testing for pregnancy loss should be based on the couple’s age, the number of miscarriages that have occurred, or if there is a known risk for recurrent pregnancy loss, such as a family history of recurrent miscarriages or being diagnosed with infertility.

Recurrent pregnancy loss may have a treatable cause, and seeking help from an infertility specialist can help address the problem.