Recurrent Miscarriage: Evidence-based Tests and Planning the Next Pregnancy
What recurrent miscarriage means, evidence-based investigations, treatments that help, tests that are not routine and planning supportive care next time.
Key message: Recurrent miscarriage is emotionally difficult and is not usually caused by ordinary activity, work or sex. Many cases remain unexplained, but the chance of a future successful pregnancy is often still good.
Get urgent help: In a current pregnancy, seek urgent care for heavy bleeding, severe or one-sided pain, shoulder-tip pain, fainting, fever, offensive discharge or feeling very unwell. This guide does not replace acute miscarriage or ectopic-pregnancy assessment.
What does recurrent miscarriage mean?
RCOG patient information defines recurrent miscarriage as three or more early miscarriages. They do not have to be consecutive, and healthy pregnancies may occur between losses.
A specialist may use clinical judgement to begin evaluation after two miscarriages when the history suggests a non-sporadic cause or when age and other factors make delay unhelpful.
Why can miscarriages recur?
- Chance chromosome problems in the pregnancy, which become more common with increasing parental age.
- Antiphospholipid syndrome (APS), an acquired clotting and immune condition.
- A congenital uterine shape such as a septum, or selected cavity-distorting fibroids or scar tissue.
- Poorly controlled diabetes, significant thyroid abnormalities, PCOS/PMOS or selected prolactin disorders.
- Parental chromosome rearrangements in a small minority.
- Smoking, very low or high weight, excessive alcohol or caffeine and some other health factors.
- In many couples no single cause is identified despite appropriate investigation.
Which investigations are evidence based?
- APS blood tests. Diagnosis requires persistent positive results on two tests at least 12 weeks apart and at least 6 weeks after a miscarriage.
- Thyroid function, including thyroid antibodies in the RCOG pathway, and diabetes testing when the history suggests risk.
- Pelvic ultrasound to assess uterine shape and the cavity; specialist imaging or hysteroscopy is selected if an abnormality is suspected.
- Genetic testing of pregnancy tissue from a third or later miscarriage when available.
- Parental chromosome testing when pregnancy tissue cannot be tested or suggests an inherited rearrangement.
- Targeted prolactin, PCOS/PMOS or other testing only when symptoms indicate it.
Which tests or treatments are not routine?
- Inherited-thrombophilia panels are not routinely recommended as a cause of recurrent early miscarriage.
- Natural-killer-cell, HLA compatibility and broad immune panels are not proven routine tests.
- Sperm DNA-fragmentation testing is not routinely offered in the RCOG/NICE pathway.
- AMH is not a routine test to explain recurrent miscarriage.
- Aspirin, heparin, steroids, intralipids, IVIG or progesterone should not be given empirically to everyone.
Which treatments can help when a cause is found?
- Low-dose aspirin plus heparin during pregnancy can improve outcomes when APS is confirmed.
- Diabetes and thyroid disease should be optimised before and during pregnancy.
- A uterine septum may be considered for hysteroscopic surgery after individual discussion; evidence for operating on every fibroid or cavity finding is not the same.
- Genetic counselling is offered when either partner has a chromosome rearrangement.
- Lifestyle support includes smoking cessation, a sustainable healthy weight, avoiding excess alcohol and keeping caffeine below 200 mg/day.
What is the role of progesterone?
Progesterone is not proven to prevent every unexplained recurrent miscarriage. If a future ultrasound confirms an intrauterine pregnancy and bleeding occurs, vaginal progesterone may be offered when there has been a previous miscarriage, following the current early-pregnancy pathway.
It should not be started without assessment because bleeding can also signal ectopic pregnancy or another urgent problem.
What if no cause is found?
Unexplained recurrent miscarriage is common. There is no proven medicine that removes all future risk, but many patients still have a good chance of a successful pregnancy.
Supportive care from an experienced team, a clear contact route and reassurance ultrasound when appropriate can reduce uncertainty even when no specific treatment is needed.
How should the next pregnancy be planned?
- Review medicines, folic acid, smoking, alcohol, caffeine, weight and chronic conditions before conception.
- Agree when to contact the team after a positive pregnancy test and when an early scan is useful.
- Know the emergency symptoms of ectopic pregnancy and heavy bleeding.
- Address anxiety, depression or post-traumatic stress; partners may grieve differently and both deserve support.
- Avoid delaying all attempts indefinitely if investigations take time—this is an individual decision after discussion of age, findings and preferences.
How is emotional recovery supported?
Repeated loss can affect sleep, work, relationships and confidence in a future pregnancy. Support should not be limited to blood tests. Counselling, mental-health care and pregnancy-loss support may be appropriate for either partner.
No one should be blamed for an unexplained loss, and a normal investigation does not mean the symptoms or grief are unimportant.
Frequently asked questions
Do the miscarriages have to be consecutive?
No. RCOG includes three or more early miscarriages even when healthy pregnancies occurred in between.
Did exercise, work or sex cause the losses?
Usually not. Most miscarriages are related to pregnancy development or other medical factors, not ordinary daily activity.
Should I take aspirin before tests are complete?
No. Aspirin and heparin are useful for confirmed APS but can be inappropriate or harmful when used without an indication.
Does unexplained mean there is no hope?
No. It means current tests did not identify a cause; the chance of a future successful pregnancy is often still good.
Will progesterone prevent every miscarriage?
No. Its evidence-based use is for selected patients with early-pregnancy bleeding and previous miscarriage after an intrauterine pregnancy is confirmed.
Your next step
Arrange a recurrent-miscarriage review with records of every pregnancy, ultrasound, pathology or genetic result and relevant blood tests. In the next pregnancy, acute pain or bleeding should follow the emergency/early-pregnancy pathway rather than waiting for a routine review.
Medical and content review: Dr Mohamed Abdelghany, Obstetrics & Gynecology Specialist, MRCOG (UK), MSc Obstetrics & Gynecology – Kasr Al-Ainy, Cairo University.
Last reviewed: 22 August 2026.
This information is for general education and does not replace individual medical assessment. Severe, sudden or concerning symptoms should not wait for a routine appointment.
