Recurrent pregnancy loss (RPL) is classically defined when a woman has experienced two consecutive early pregnancy losses.
Spontaneous miscarriages are common, with approximately 10-15% of pregnancies result in a miscarriage. However fewer than 5% of women will experience two consecutive miscarriages, and only 1% will experience 3 or more. Therefore RPL is distinct from sporadic miscarriages and warrants additional evaluation.
What causes RPL? How do we diagnose and treat?
Evaluation of RPL should be tailored to the patient’s history, but often involves a systematic investigation for different causes including: genetic, immunologic, anatomic, and endocrine factors.
RPL may result from an abnormal number of chromosomes “aneuploidy” in the embryo or some type of inherited structural abnormality in the chromosomes of the embryo. Embryos with an abnormal number of chromosomes occur in all women regardless of age, but occur more frequently in women that are older. Inherited structural chromosomal abnormalities are abnormalities that get passed down from parent to embryo. In either scenario, embryos made during the process of IVF can be tested to detect the abnormalities with two similar techniques called preimplantation genetic testing for aneuploidy (PGT-A), once PGS, or preimplantation genetic testing for monogenic disorders(PGT-M), formerly PGD.
All patients experiencing RPL should have genetic testing to test their own chromosomes to look for abnormalities that could get passed on to the embryos, thus causing miscarriages. Fetal cell free DNA, amniocentesis or chorionic villus sampling are other options to detect genetic abnormalities in the offspring. PGT-A and PGDT-M are often preferred as they are performed before implantation occurs.
Antiphospholipid syndrome (APLS) is an autoimmune disorder that can cause repetitive miscarriages and sometimes late pregnancy losses. It is tested for by doing a blood test. Additional medical and obstetric complications of APLS positive women include clot formation, stroke and other pregnancy complications. The optimal treatment of women with APLS includes prophylactic use of an anticoagulant and baby aspirin—with some studies showing up to a 50% reduction in pregnancy loss.
The uterus and the uterine cavity should also be evaluated for congenital uterine abnormalities which can be surgically corrected. Other uterine abnormalities including uterine fibroids that distort the uterine cavity, uterine polyps, and uterine scarring may also be associated with RPL and may be surgically corrected.
Tests of hormone function may also be done. Thyroid function tests and thyroid antibodies may be checked, along with testing for diabetes if a woman is at risk for developing diabetes.
Outcomes for all women with RPL
Despite full work up of potential causes of RPL, approximately 50% of patients will not have an identifiable cause. In these cases, a variety of treatments may potentially be offered, but none are universally recommended. Most providers would recommend increased clinical surveillance and progesterone supplementation after ovulation. The overall chance of pregnancy is good, even without treatment a woman has a 60-80% chance of conceiving and carrying a full-term pregnancy.