Recurrent pregnancy loss (RPL) is a separate pathological phenomenon and is defined by at least two or three consecutive clinical miscarriages. Fewer than 5% of women experiencing two consecutive miscarriages and fewer than 1% of women have three or more.
Various causes are responsible for RPLs. For example:
- Advanced maternal or paternal age
- Antiphospholipid syndrome (APLS): APLSs are characterized by recurrent miscarriages and the presence of antibodies that increase the formation of blood clots. About 8 to 42% of women with RPL had tested positive for antiphospholipid antibodies.
- A predisposition for thrombosis (hereditary thrombophilia)
- Anatomical uterine factors: Uterine cavity abnormalities are present in 13% of women with RPL, compared to 4% in the general population. These abnormalities can be present at birth (arcuate uterus, unicornuate uterus, bicornuate uterus, etc.), or acquired (uterine fibroids).
- Metabolic or hormonal disorders: A hormonal imbalance can cause recurrent miscarriages. It’s important to ensure that the thyroid gland is functioning properly and that diabetes is well-controlled, if applicable.
- Abnormal sperm quality: Until recently, the man’s role in recurrent miscarriages was not taken into consideration. More and more studies confirm the important role of multiple male factors. We now know that changes to the DNA of sperm cells reduces the rate of fertility, causes developmental defects in the embryo, and causes spontaneous miscarriages.
- Genetic factors: Chromosomal abnormalities in the parents are rare in cases of recurrent pregnancy losses (RPL). This risk is typically low at 2 to 5%.
- Poor lifestyle (see the section on Diet)
- In many cases of recurrent miscarriage, the cause for these losses is unexplained.