It can be physically and emotionally challenging to miscarry one baby after another. With each new pregnancy, there is hope and anxiety. And, every new loss can be difficult to bear for a woman. The heart breaking experience can put huge stress on even the strongest relationships. There is a chance of both the partners to react differently from each other which can result in great tension and conflicts. There can be different causes behind miscarriages. Some women can even have more than one miscarriage in a lifetime.
What is recurrent miscarriage? Recurrent miscarriage is the term used for having three or more miscarriages in a row. This mishappening occurs one in every hundred couples trying for a baby. In some cases, a treatable cause can be found, and sometimes not. However, in both cases, most of the couples have higher chance of a successful pregnancy the next time than to miscarry again. Onlymyhealth editorial team spoke to Dr. Rishma Pai, Mumbai's leading gynaecologist & Infertility specialist attached to Jaslok, Lilavati & Hinduja, Healthcare Hospitals, about the causes of recurrent miscarriages.
Causes of recurrent miscarriage
Family and friends might find it difficult to support you after every miscarriage. Moreover, they might even think that you are getting used to the loss and will be able to cope on your own now. According to Dr. Rishma, here are the 6 main causes of recurrent miscarriage:
1. Antiphospholipid syndrome (APS)
Antiphospholipid syndrome is a blood clotting problem and a treatable cause of recurrent miscarriage. It happens if your immune system produces abnormal antibodies that affect fats called phospholipids in your bloodstream. This makes the blood more thick and sticky and at a higher risk to clot, which is why APS is also called ‘sticky blood syndrome’. It is known as ‘Hughes syndrome’ after the expert who named it. The cause behind these antibodies leading to miscarriage is still unknown. They can stop the pregnancy from embedding completely in the uterus (womb) or they can restrict the blood flow to the placenta, which supports the baby.
APS can also lead to problems in later pregnancy, such as the baby not growing properly, pre-eclampsia or stillbirth. Other blood clotting disorders and some inherited blood clotting issues can lead to recurrent miscarriage, especially after 14 weeks. These include factorV Leiden, factor II (prothromobin), gene mutation and protein S deficiency.
2. Abnormal chromosomes
The chromosomes in each cell of the body carry hereditary information in the form of genes. Everyone has 23 pairs of chromosomes, and 22 of them are the same in men and women. The 23rd one is different because they determine the gender of a person. Normally, men have one X and one Y chromosome and women two X chromosomes. A baby inherits half of the chromosomes from each parent. Most of the miscarriages happen because the baby’s chromosomes are abnormal. This is not inherited and it usually happens when the egg and sperm meet soon after the egg is fertilised.
It is rare (in less than five in one hundred couples with recurrent miscarriage) that one partner has chromosomal defect called a ‘balanced translocation’. This does not lead to any problems for the parent, but it can be present in to the baby as an ‘unbalanced translocation’. This indicates that some genetic information is doubled up while some can be missing.
3. Cervical weakness (also called ‘incompetent cervix’)
Your cervix plays the role of a ‘gateway’ between the uterus and vagina, which usually widens in labour to allow the birth of the baby. Some women, in very rare cases might have a weakness in the cervix that helps it dilate too early. This is a common and known cause of late (second trimester) miscarriage.
4. Abnormally-shaped uterus
In some miscarriages, especially late ones, can happen because the uterus (womb) has an abnormal shape, termed as abnormally shaped uterus. It can be divided down the centre, also called ‘bicornuate’ or ‘septate’ uterus; or just one half of the uterus might have developed, known as ‘unicornuate’ uterus. There is no clear evidence from research about women with recurrent miscarriage having these abnormalities.
5. Polycystic ovary syndrome (PCOS)
Women suffering from the condition PCOS might have many small cysts in their ovaries. They can also have hormonal problems, such as increased levels of insulin and male hormones in the blood. As a result, these problems might have a role to play in causing recurrent miscarriage, but it is still not clear how.
Some serious infections can increase the risk of single miscarriages. Such infections are toxoplasmosis, rubella, listeria and genital infection. However, it is not known whether infection plays a role in recurrent miscarriage or not. Immune problems, high levels of uterine NK (uNK) cells can also put you at a higher risk of recurrent miscarriage, but more research is needed to prove this.
It is essential to know that these uNK cells are different from the NK cells found normally in circulating blood (e.g. from your arm). Uncontrolled diabetes and uncured thyroid can also cause miscarriage. However, diabetes and thyroid problems do not lead to recurrent miscarriage.
Why do recurrent miscarriages happen?
There are certain risks that can increase your risk of having a recurrent miscarriage. The risk factors of recurrent miscarriage that can put you at a greater risk are:
- You and your partner are at an older age as the risk is highest if you are over the age of 35 and your partner over 40
- You are obese or overweight. Being very underweight can also increase your risk of recurrent miscarriages
- Every new pregnancy loss increases the risk of a further miscarriage. However, even after three miscarriages, most of the couples have a live baby the next time