Cases of recurrent miscarriages affect 1-2% of couples. It is considered that a couple has a history of recurrent miscarriages when they have two or more consecutive miscarriages.
- Advanced maternal or paternal age is thought to be independent risk factors for miscarriage. The risk increases especially for women over 35 years old and for men who are over 40 years old.
- History of miscarriages
- Acquired or inherent thrombophilia
- Fetal chromosomal abnormalities
- Maternal or paternal chromosomal abnormalities
- Congenital uterine anomalies
- Thyroid disease
As far as second trimester miscarriages are concerned, there appear to be other causes such as:
- cervical deficiency
- bacterial vaginosis
However, in many cases, recurrent miscarriages are of unknown aetiology, meaning that there is no cause found.
- Fetal karyotype
Chromosomal abnormalities of the fetus are the most common cause of miscarriages in the first trimester of pregnancy.
- Karyotype of the couple
In 2-5% of the couples with a background history of recurrent miscarriages, in comparison with 0.7% in the general population, either the father or the mother are healthy carriers of a balanced genetic translocation. The risk of a chromosomal abnormality in the fetus is 5-10%.
- 3D gynaecological ultrasound
Congenital uterine abnormalities are more common in women with a background history of recurrent miscarriages. 3D gynaecological ultrasound is necessary for the diagnosis of congenital uterine abnormalities, like uterine septum and bicornuate uterus.
- Antiphospholipid syndrome
The antiphoshpolipid syndrome is a type of thrombophilia that appears to exist in 15% of women with a background history of recurrent miscarriages. A blood examination plus a relevant background history are necessary for its diagnosis. Antiphospholipid syndrome is the commonest cause for recurrent miscarriages for which there is a medical treatment.
- Endocrine diseases
Abnormalities of the thyroid’s function, even the mildest, are linked to recurrent miscarriages. It is suggested that women, who are trying to conceive, have a TSH<2.5 mlU/L. Women with diabetes also have an increased risk of miscarriage and of congenital fetal abnormalities.
- Measurement of the length of the uterine cervix
The cervix is the lowest part of the uterus which remains closed during pregnancy and dilates during labour. If it starts shortening too early in pregnancy, there is an increased risk of miscarriage in the second trimester.
The measurement of the length of the uterine cervix should be conducted vaginally from specialized doctors. Dr Ioanna Tsoumpou has trained at Harris Birthright Centre of Fetal Medicine at King’s College Hospital in London. She is certified from the Fetal Medicine Foundation for the vaginal measurement of the uterine cervix and the assessment of risk for second trimester miscarriage and preterm labour.
The assessment of the uterine cervix can be conducted in the first trimester of pregnancy during the nuchal scan and during the fetal anomaly scan at 21-24 weeks of gestation. Depending on the background history, we might need to conduct the scan also at 16-18 weeks of pregnancy.
The management of couples with a background history of recurrent miscarriages needs to be individualized.
- History of chromosomal abnormalities of the couple
All couples with balanced translocations need to be referred for genetic consultation so as to discuss possible interventions like pre-implantation genetic diagnosis PGD or chorionic villus sampling CVS in future pregnancies.
- Congenital uterine abnormalities
The management of congenital uterine abnormalities is dependent on the type of the abnormality and the woman’s past obstetric history. For women with a history of recurrent miscarriages who have a uterine septum, it is usually suggested operative hysteroscopy and resection of the septum.
The repair of a bicornuate uterus requires surgery (metroplasty) that is connected with a high risk of complications without proven benefits, so it is not recommended.
Didelphys and unicornuate uteri are behaving as a normal uteri and do not require surgery.
- Antiphoshpolipid syndrome
Women diagnosed with antiphospholipid syndrome need special medical management and consultation in cooperation with a haematologist.
- Endocrine abnormalities
Abnormalities of the thyroid function, even the mildest, have to be addressed. We suggest that women who are trying to get pregnant and women at the first trimester of pregnancy have TSH<2.5 mlU/L. Similarly, women with a history of diabetes or insulin resistance need first to control their blood glucose levels and then start the efforts to conceive.
- Cervical insufficiency
Women with a history of second trimester miscarriage due to short uterine cervix are advised to have a cervical cerclage.
- Recurrent miscarriages of unknown aetiology
For a vast majority of couples (50% on average), we cannot identify the cause of recurrent miscarriages. It is widely accepted that psychological support and a healthier lifestyle (weight loss, exercise, giving up smoking, stress control, limited alcohol consumption) are very important factors that increase the chance of an uncomplicated pregnancy.
For more information you could visit the following websites: