Causes of recurrent miscarriage – tests and improving chances of success

Losing a much wanted pregnancy is heart-breaking and it is natural to want to know what went wrong or even to blame yourself. Sadly there are many possible causes of recurrent miscarriage and the reason may never be known. 

It is important not to see miscarriage as any kind of personal failure or to give up as, statistically, most people who experience a loss go on to have a healthy pregnancy.

However, for those who have a recurrent miscarriage (three or more losses), there may be an underlying reason, so referral to a specialist unit and fertility treatment can be helpful.

Causes of recurrent miscarriage – tests and improving chances of success
Hope after a storm

Known causes of recurrent miscarriage

The reasons for miscarriage are not fully understood but the following are thought to be factors:

  • Antiphospholipid syndrome (APS) – a treatable blood clotting problem that effects about 10-15% of women with recurrent miscarriage. It can stop the pregnancy embedding properly in the womb or interfere with the blood flow to the placenta which supports the baby. It can be treated with a low dose of aspirin and blood thinner injections. More information on APS.
  • Abnormal chromosomes – A baby inherits half its chromosomes from each parent – the father’s in the sperm and the mother’s via the egg. When the two are combined in the embryo sometimes the process doesn’t work properly and the embryo has too many or too few chromosomes. One or both of the parents might carry a chromosome defect that doesn’t affect their health but may cause an issue for reproduction. This can be diagnosed with blood tests. For an explanation of chromosome translocation see this helpful video.
  • Weakness in the cervix – Some women – probably less than one in a hundred – have a weakness in the cervix at the bottom of the womb that allows it to dilate too early and this is known cause of later miscarriage (typically after the first three months of pregnancy). For some women this can be ‘stitched’ to help the pregnancy hold – see Elsa’s story.
  • Abnormally shaped uterus – this can be detected with a 3D scan or a hysteroscopy, where a special viewing tube is inserted through the vagina. Some abnormalities can be corrected with surgery.

Other possible causes include an infection or issues with the hormones such as thyroid issues or Polycystic Ovary Syndrome (PCOS).

Risk factors 

Although not in themselves the cause of miscarriage, being older, being over or under weight, being a smoker and stress are all risk factors. Also it is advised to cut alcohol and improve your health and nutrition.

Stress can affect your hormones, creating a vicious circle, so trying gentle walks in the open air and mindfulness as part of your strategy for reducing stress can help your mental wellbeing and your ability to cope with treatment. Many people also find Fertility Network UK and Bourn Hall’s Fertility Support Group helpful.

Sarah - IVF gave me hope after baby loss heartache
"IVF treatment gave me hope after recurrent miscarriage," says Sarah

How fertility treatment can help

Many of the causes of recurrent miscarriage identified above can be diagnosed with dedicated testing. At Bourn Hall it is possible to have a consultation to go through your medical history and a suite of tests designed to diagnose or eliminate these common reasons.

Test may include:

  • autoimmune and blood clotting disorders
  • testing for hormonal imbalance
  • evaluation of ovulation and progesterone levels
  • inspection of the uterus for abnormalities
  • testing for infections

Additional progesterone – There is also emerging evidence that additional progesterone may help women that have had a bleed early in pregnancy to go to full term, and this can be prescribed as a pessary or tablets. Progesterone is produced naturally before and after pregnancy to help thicken the lining of the womb. The PRISM trial by the charity Tommy’s showed that additional progesterone increased the live birth rate in women that had previously experienced three or more miscarriages and had a bleed early in pregnancy. The live birth rate was 72% (98/137) in the progesterone group and 57% (85/148) in the placebo group, ie a substantial benefit.

Screening of the embryos – If abnormal chromosomes are suspected and the couple have been advised to try IVF treatment, then the embryos can be screened for these types of abnormalities. A test known as as Pre-implantation Genetic testing for Aneuploidy (PGT-A) or Pre-implantation Genetic Screening or PGS detects chromosome mistakes in an embryo. Use of this technology can help embryologists select an embryo that is most likely to succeed. More about PGT-A / PGS at Bourn Hall.

Endometrial receptivity – Endometrium is the tissue where implantation occurs. The embryo attaches to the endometrium (uterine lining) and gets all the nutrients from it during pregnancy. Bourn Hall offers ERA – Endometrial Receptivity Analysis to help determine the optimal time for frozen embryo transfer.

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