Repeated miscarriages are sometimes called recurrent pregnancy loss (RPL). Although the exact definition can vary between medical organizations, recurrent pregnancy loss generally refers to having two or more pregnancy losses.
What Causes Repeated Miscarriages?
There is not always one obvious cause. Several biological, genetic, hormonal, anatomical, and lifestyle factors may contribute.
- Chromosomal Problems
One of the most common explanations for miscarriage is a chromosomal abnormality in the developing embryo. These abnormalities can occur randomly when the egg or sperm contributes an incorrect number or structure of chromosomes.
Many chromosomal abnormalities prevent normal development, resulting in miscarriage. Importantly, this does not necessarily mean that either partner has a genetic problem.
- Age-Related Changes
The risk of miscarriage increases as maternal age increases, partly because the likelihood of chromosomal abnormalities in eggs also increases.
Age-related changes can therefore be an important factor when evaluating repeated pregnancy loss, particularly in women in their late 30s and 40s.
- Uterine Abnormalities
Problems affecting the structure of the uterus may make it difficult for a pregnancy to implant or develop normally.
Examples include:
- Fibroids that affect the uterine cavity
- Uterine polyps
- A uterine septum
- Certain congenital uterine abnormalities
- Scar tissue inside the uterus
A healthcare professional may recommend an ultrasound or other imaging tests to examine the uterus.
- Hormonal and Metabolic Conditions
Certain medical conditions can increase the risk of pregnancy loss if they are not properly controlled.
These may include thyroid disorders and poorly controlled diabetes. Some hormonal disorders may also affect ovulation or the ability of the uterine lining to support pregnancy.
Proper medical assessment and treatment can help manage some of these risks.
- Antiphospholipid Syndrome
Antiphospholipid syndrome (APS) is an autoimmune condition associated with an increased risk of blood clots and pregnancy complications, including recurrent miscarriage.
When APS is suspected, doctors may perform specific blood tests. If diagnosed, appropriate treatment during pregnancy can significantly reduce pregnancy-related complications for many patients.
- Genetic Factors in Either Partner
In some couples, one partner may carry a chromosome rearrangement called a balanced translocation. The carrier may be healthy, but the rearrangement can sometimes result in embryos with an unbalanced chromosome arrangement.
Genetic counselling and appropriate testing may be recommended when recurrent pregnancy loss is suspected to have a genetic component.
- Infections and Other Medical Conditions
Some infections and underlying medical conditions can contribute to pregnancy complications. However, not every infection commonly blamed for miscarriage has been shown to cause recurrent pregnancy loss.
This is why testing should be guided by a qualified healthcare professional rather than relying on unproven tests or treatments.
- Lifestyle and Environmental Factors
Certain lifestyle and environmental factors may increase miscarriage risk.
These can include:
- Smoking
- Excessive alcohol consumption
- Recreational drug use
- Obesity or being significantly underweight
- Exposure to certain environmental toxins
Improving overall health before pregnancy can help reduce some preventable risks.
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Can Stress Cause Repeated Miscarriages?
Everyday emotional stress is not generally considered a direct cause of miscarriage. Pregnancy loss can happen even when someone has been doing everything correctly.
It is important not to blame yourself or your partner after a miscarriage. Grief, anxiety, and emotional distress following pregnancy loss are understandable, and seeking emotional support can be beneficial.
When Should You See a Doctor?
If you have experienced two or more miscarriages, it is reasonable to discuss your history with a doctor or fertility specialist. Depending on your circumstances, evaluation may include:
- A detailed medical and pregnancy history
- Blood tests
- Assessment of thyroid and metabolic health
- Testing for antiphospholipid syndrome
- Examination of the uterus
- Genetic testing or genetic counselling in selected cases
The appropriate investigations depend on your individual history.
Can Repeated Miscarriages Be Prevented?
Unfortunately, not every miscarriage can be prevented. Many early miscarriages result from chromosomal abnormalities that occur randomly.
However, identifying an underlying cause can sometimes allow doctors to recommend treatment or management strategies that improve the chances of a successful pregnancy.
Before trying to conceive again, it may be helpful to discuss your medical history, medications, lifestyle, and previous pregnancy losses with a healthcare professional.
Final Thoughts
The reasons for repeated miscarriages can range from chromosomal abnormalities and age-related changes to uterine abnormalities, autoimmune conditions, hormonal disorders, and other health factors. In some cases, doctors cannot identify a specific cause even after thorough investigation.
Repeated pregnancy loss is not necessarily a sign that you cannot have a healthy pregnancy. If you have experienced multiple miscarriages, seek appropriate medical evaluation rather than assuming that you or your partner caused the losses.
If you are currently pregnant and experiencing heavy bleeding, severe abdominal or pelvic pain, dizziness, fainting, or other concerning symptoms, seek urgent medical attention.