Recurrent Miscarriage
Understanding recurrent pregnancy loss and paths forward.
Key Points
- Definition: Two or more pregnancy losses (some define as three)
- Affects: ~1-2% of couples trying to conceive
- Identifiable cause: Found in about 50% of cases
- Good prognosis: Even after 3 losses, 60-75% eventually have successful pregnancy
What Is Recurrent Pregnancy Loss?
Recurrent pregnancy loss (RPL)—also called recurrent miscarriage—is defined as two or more clinical pregnancy losses. The American Society for Reproductive Medicine (ASRM) recommends evaluation after two losses, while some older guidelines used three.
A "clinical pregnancy" means one confirmed by ultrasound or histology, not just a positive pregnancy test (though chemical pregnancies can also indicate issues).
📊 Understanding the Numbers
• ~15-25% of all recognized pregnancies end in miscarriage
• Two consecutive miscarriages: ~2-3% of couples
• Three consecutive miscarriages: ~0.5-1% of couples
• After 2 losses, risk of another is ~25-30%
• After 3 losses, risk of another is ~30-40%
Important: These numbers also mean that even after multiple losses, the majority of women will eventually have a successful pregnancy.
Causes of Recurrent Miscarriage
In about 50% of cases, a specific cause can be identified. The other half remain "unexplained"—which actually has a good prognosis.
🧬 Chromosomal/Genetic Factors (50-60% of losses)
Random chromosomal errors: The most common cause of any single miscarriage. The embryo receives the wrong number of chromosomes and cannot develop. This is usually random and doesn't indicate a recurrent problem.
Parental chromosomal abnormalities: In ~3-5% of couples with RPL, one partner carries a balanced translocation or other chromosomal rearrangement. They're healthy, but their eggs or sperm may have unbalanced chromosomes.
Testing: Karyotype (chromosome analysis) of both partners
🏠 Uterine Abnormalities (10-15%)
Structural issues with the uterus can prevent implantation or development:
- Uterine septum: A wall of tissue dividing the uterus (most common structural cause)
- Fibroids: Especially those distorting the uterine cavity
- Polyps: Growths in the uterine lining
- Asherman's syndrome: Intrauterine adhesions/scarring
- Congenital abnormalities: Bicornuate or unicornuate uterus
Testing: HSG, SIS, hysteroscopy, MRI
🔬 Thrombophilias (Blood Clotting Disorders)
Conditions that increase blood clotting can affect placental blood flow:
- Antiphospholipid syndrome (APS): The most important treatable cause. Autoimmune condition causing blood clots.
- Inherited thrombophilias: Factor V Leiden, prothrombin mutation, etc. (role in RPL is debated)
Testing: Antiphospholipid antibodies (lupus anticoagulant, anticardiolipin, anti-beta2 glycoprotein)
🧪 Hormonal/Endocrine Factors
- Thyroid disorders: Both hypo- and hyperthyroidism, plus thyroid antibodies
- Uncontrolled diabetes: Elevated A1C increases miscarriage risk
- PCOS: May be associated with higher miscarriage rates
- Luteal phase defect: Controversial; insufficient progesterone after ovulation
Testing: TSH, thyroid antibodies, fasting glucose/A1C, prolactin
📅 Age & Egg Quality
Advanced maternal age is associated with higher miscarriage rates due to increased chromosomal abnormalities in eggs. This is the most common "cause" in women over 35-40.
🤷 Unexplained (40-50%)
Despite thorough testing, no cause is found. Surprisingly, this group has the best prognosis—65-70% will have a successful pregnancy without any treatment.
Evaluation & Testing
After two miscarriages, your doctor should offer a workup:
| Test | What It Checks |
|---|---|
| Karyotype (both partners) | Chromosomal abnormalities |
| Antiphospholipid antibodies | APS (blood clotting disorder) |
| TSH & thyroid antibodies | Thyroid function |
| Pelvic ultrasound | Uterine structure, fibroids, ovaries |
| HSG or SIS | Uterine cavity & tubes |
| MRI (if indicated) | Detailed uterine anatomy |
| Hysteroscopy (if indicated) | Direct view of uterine cavity |
💡 Testing the Pregnancy Tissue
If you have another miscarriage, ask about chromosomal testing (karyotype or microarray) of the pregnancy tissue. This can determine if the loss was due to a chromosomal abnormality, which provides valuable information for future planning.
Treatment Options
For Antiphospholipid Syndrome
Combination of low-dose aspirin and heparin (blood thinner) significantly improves live birth rates—from ~10-20% to ~70-80%. This is the most successful treatment for an identified RPL cause.
For Uterine Abnormalities
Surgical correction of septum, fibroids, polyps, or adhesions. Uterine septum removal has the best evidence for improving outcomes.
For Chromosomal Issues in Parents
IVF with preimplantation genetic testing (PGT) can select embryos with normal chromosomes. Alternatively, donor eggs or sperm may be discussed.
For Thyroid Disorders
Treatment to optimize thyroid function (TSH ideally 0.5-2.5 mIU/L during pregnancy).
For Unexplained RPL
Options include:
- Supportive care: Close monitoring, early ultrasounds, reassurance. Studies show this alone improves outcomes—possibly by reducing stress.
- Progesterone supplementation: Evidence is mixed, but may help some women, especially with history of early losses.
- Baby aspirin: Low-dose aspirin is sometimes prescribed empirically.
- IVF with PGT: To select chromosomally normal embryos, reducing miscarriage risk.
⚠️ Treatments That Don't Work
Some commonly offered treatments lack evidence:
• Immunotherapy (IVIG, intralipids) for "immune causes" — not proven effective
• Paternal leukocyte immunization — not effective, potentially harmful
• Routine anticoagulation without APS diagnosis — not proven beneficial
The Emotional Toll
Recurrent miscarriage is a grief that compounds. Each loss can feel harder than the last. You may experience:
- Profound grief and sadness
- Anxiety about future pregnancies
- Fear of trying again
- Guilt or self-blame (unwarranted)
- Isolation from friends and family who don't understand
- Relationship strain
- Depression or PTSD symptoms
Getting Support
- Therapy: Especially with someone specializing in pregnancy loss
- Support groups: Connecting with others who understand
- Partner communication: You may grieve differently
- Self-compassion: This is not your fault
💜 It's Not Your Fault
Miscarriage is not caused by exercise, sex, stress, coffee, or anything you did or didn't do. In most cases, it's a chromosomal abnormality completely beyond your control. Please be gentle with yourself.
Reasons for Hope
Despite the pain of RPL, the statistics offer real hope:
- After 2 miscarriages: ~65-75% will have a successful pregnancy
- After 3 miscarriages: ~60-70% will have a successful pregnancy
- With unexplained RPL: ~65-70% success with supportive care alone
- With APS and treatment: ~70-80% success
Every pregnancy is a new chance. Your history doesn't determine your future.
The Bottom Line
Recurrent miscarriage is heartbreaking, but it's important to know: the majority of women with RPL will eventually have a successful pregnancy. Seek evaluation after two losses, work with a specialist, and allow yourself to grieve while holding onto hope.
Your losses are real. Your grief is valid. And your chances are better than you might think. 💜