7 common causes of miscarriages

There is no experience more difficult than having to go through a miscarriage during pregnancy. Miscarriage is not only physically taxing, but very emotionally challenging as well. Yet, pregnancy loss can be even harder to deal with especially when it occurs time and time again

One out of every 5 to 6 pregnancies ends in a miscarriage i.e. the pregnancy is lost. And if it happens three times in a row to a woman, then it can be disastrous. Recurrent pregnancy loss is one such situation which carries the burden of immense emotional stress to the couple concerned.

To understand the cause of such losses in a particular couple, it is important to investigate the couple completely.

Various tests are carried out to determine the cause of the problem, which could vary from being hormonal, to infective or genetic. The treatment varies depending on the cause; hence it is not possible to prevent the problem again, unless all the necessary tests are done.

Does the male partner share equal responsibility for infertility?
Dr Duru Shah

Chromosomal causes

At least 50% of the pregnancies that are lost in the first 3 months have a major chromosomal or genetic abnormality when the pregnancy tissues are examined.

For foetuses lost later in pregnancy, there is also a high rate of chromosomal abnormality, roughly 30% in the second 3 months of pregnancy and 5% in the last 3 months.

Women older than 35 years have a greater tendency to produce eggs with chromosomal abnormalities.

Immunologic causes

Two major categories of immunologic causes of recurrent pregnancy loss are autoimmune (in which the woman’s immune system attacks her own organs and tissues) and alloimmune (in which the immune systems attacks tissues considered foreign). Autoimmune disease or dysfunction may play a role in up to 10% of recurrent pregnancy loss.

Antiphospholipid (APS) is the autoimmune dysfunction that is classically associated with recurrent pregnancy loss. Small blood clots develop in the circulation of the foetus which interrupts the passage of oxygenated blood to the foetus.

This is a possible reason for the foetal losses. Low dose aspirin and Heparin (blood thinners) are the preferred treatment options for women with APS.

Hormonal causes

The commonest hormonal cause for recurrent pregnancy loss is “the luteal phase defect” which is associated with a low progesterone secretion.

Progesterone appears to have a critical role in implantation and the development of a normal pregnancy and its deficiency can lead to infertility in severe cases and recurrent pregnancy loss in milder cases.

A common treatment for a luteal phase defect is progesterone supplementation in the form of vaginal suppositories, injections, oral tablets or a combination of the above.


Certain chronic infections such as toxoplasmosis which a woman may suffer from can be passed to the foetus, causing it harm. If the infection is not detected, it may continue to play havoc with further pregnancies. Hence it is necessary to carry out various tests, treat the infections if present and this can then lead to successful pregnancies in future.

Uterine abnormalities

Abnormalities of the uterus such as defects in the structure of the uterus since birth, or presence of fibroids in the cavity of the uterus, or a septum (partition) in the cavity, or an incompetent OS (mouth of the uterus) can lead to miscarriages. Correcting these problems before the next pregnancy can definitely help prevent miscarriages.

Lifestyle factors

Certain lifestyle factors can also increase the risk of experiencing recurrent miscarriage, particularly smoking, heavy drinking and drug abuse.

Unknown causes

After complete investigation, as doctors, we may still not find a cause for a couple’s recurrent miscarriages. Studies have found that couples with recurrent miscarriages due to unknown causes have a 70% chance of eventually having a normal pregnancy.

The author is the Director of Gynaecworld Center for Assisted Reproduction and Women’s health and Panel Consultant – Breach Candy Hospital and Jaslok Hospital