When there are recurrent miscarriages (more than two), it is important to find a common link that may explain why this happened. Sometimes, the cause may be an abnormality in the uterus or cervix, a medical condition (you might not have even known about!), an imbalance in your hormones, a reaction to pregnancy by your immune system, or an abnormality with chromosomes.
In recurrent miscarriages, part of the genetic information may not “line up” correctly or the parts may have a missing, extra, or defective piece. In such cases, you and your clinician should discuss the value in seeing a geneticist or genetic counselor to help identify the cause, and to plan for future pregnancies.
Pre-existing Medical Conditions
Some medical conditions associated with recurrent miscarriage include systemic lupus erythematosus (SLE), hypothyroidism (an underactive thyroid) and uncontrolled diabetes mellitus. In such cases, your clinician will work with your internist or medical specialist to help identify the cause, and work with you on future pregnancy attempts.
Uterine and Cervical Defects
Other maternal factors commonly involved in miscarriage are related to abnormalities of the cervix and uterus. Cervical incompetence is a condition where the cervix is abnormally weak. Under pressure of the growing fetus, the cervix begins to open prematurely. Cervical incompetence is most commonly found in women who have had previous treatments to the cervix such as cone biopsy, dilation procedures (for abortion or miscarriage), or DES exposure in-utero
DES (diethylstilbestrol) is a synthetic estrogen widely prescribed during 1940’s to 1970’s to prevent miscarriage. It later was found that DES crossed the placenta causing damage to the reproductive system of the fetus. With early identification, cervical incompetence may be treated with cerclage, a procedure in which the cervix is surgically sewn closed to add strength to the cervix. The stitches are removed before labor.
Most uterine defects are present since birth though an abnormality may not be detected until problems with pregnancy require further investigation. Defects such as an abnormally shaped uterus, (heart shaped, or with a septum [wall] dividing it) may interfere with maintaining a pregnancy. Uterine fibroids (non-cancerous smooth muscle tumors that grow from the wall of the uterus) can protrude inside and outside the uterus impeding embryo implantation and carrying a pregnancy to term.
In such cases, your clinician should discuss the available treatment alternatives and work with you as you consider future pregnancy attempts.
Luteal Phase Defects (LPD)
Some women who monitor their basal body temperature (BBT) may find that the luteal phase (time in the menstrual cycle after ovulation and before your period) temperatures do not stay reliably elevated, as is necessary to support pregnancy. BBT is used to observe for ovulation by monitoring your temperature every day at the same time for several menstrual cycles. Normally when you are pregnant, the temperature after ovulation is elevated and remains that way.
With a luteal phase defect, the temperature doesn’t stay elevated which effects the development and implantation of the embryo. For those women who don’t follow their BBT or ovulation and miscarry, LPD may go unrecognized.
Luteal phase defect is a failure of the uterine lining to be in the right phase at the right time. Since embryo implantation is very dependent on the lining being just right, LPD may interfere with a woman's ability to get pregnant and carry a pregnancy successfully. The uterine lining relies on the hormone progesterone to support the early stages of pregnancy before implantation has occurred. In some cases of LPD there is decreased progesterone. In other cases, LPD can stem from poor follicle production earlier in the menstrual cycle or, from premature failure (does not persist as long as it should) of the corpus luteum.
In such cases, your clinician should discuss the treatment alternatives available and work with you as you consider future pregnancy attempts.
Recent research suggests that couples who experience multiple miscarriages may do so because of immune system problems. The immune system is the first line of defense against disease. Antigens are markers on your cells that identify substances as natural or foreign. When antigens recognize a foreign substance, they will start production of antibodies to defend the body. An abnormal antibody response occurs when the pairing of genes from the man and woman are recognized as unrelated. This immune reaction can be either autoimmune or alloimmune:
- Autoimmune — a woman rejects her own body proteins
- Alloimmune — a woman reacts against the foreign proteins from the man.
Treatment for these responses is based on the type of reaction and may include steroids to suppress the reaction, medications to thin the blood and immunization therapy. Your clinician will work with you if your recurrent miscarriages are caused by immune factors.