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Miscarriage: Causes

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Around one in four or five pregnancies end in miscarriage. In most cases it is impossible to know what caused it, but the majority of early miscarriages are thought to be caused by a chromosome abnormality in the baby.

If, at the point of fertilization, the baby does not receive the required 46 chromosomes from both parents, then it will not be able to continue to develop and the pregnancy will be lost.

Other causes of miscarriage are:

Placental problems – if the placenta fails to develop normally this can result in an early miscarriage.

Infections – for instance, listeria or other food poisoning illnesses, sexually transmitted infections or vaginal infections such as bacterial vaginosis.

Immune system problems – if the woman has too many antibodies called antiphospholipid (aPL) in their blood this can cause blood clots which in turn can cut off the blood supply to the baby and cause a miscarriage.

This is sometimes the cause of recurrent miscarriages (three or more in a row). If this happens to you, you may be offered low dose aspirin or heparin or both to prevent blood clotting and maintain the pregnancy.

Autoimmune issues can also cause miscarriage. In a healthy pregnancy, the mother’s immune system is prevented from rejecting the developing baby, but some medical professionals think that if she produces a high number of natural killer cells, this can end the pregnancy.

Chronic health problems during pregnancy, such as diabetes, kidney disease, celiac disease, lupus, or thyroid disease can result in miscarriage.

Medications – if you have to take medications during pregnancy, for instance, ibuprofen for osteoarthritis, this can increase the risk of miscarriage. It is best to avoid medications in the first 12 weeks of pregnancy unless there is no other choice. Your doctor may be able to modify your medication to a kind that is least risky to your baby.

Caffeine – Too much caffeine may cause miscarriage. More than two cups of coffee per day is considered to increase the risk of miscarriage.

Uterine Abnormalities – conditions of the uterus, such as fibroids or Asherman’s syndrome (extensive scarring of the womb that can sometimes occur after a D+C or use of an IUD). This can make it difficult for the embryo to successfully implant into the wall of the uterus.

Smoking or drinking alcohol during pregnancy.

Abusing illegal drugs during pregnancy.

Being obese can increase your risk of miscarriage.

Women who are over the age of 42 at the time of conception have a 50 percent chance of miscarriage.


1. Miscarriage, Patient UK. Web. 5 October 2011. http://www.patient.co.uk/health/Miscarriage.htm

2. Miscarriage, Bupa Healthcare. Web. 5 October 2011. http://www.bupa.co.uk/individuals/health-information/directory/m/miscarriage

3. Causes of Miscarriage, NHS Choices. Web. 5 October 2011. http://www.nhs.uk/Conditions/Miscarriage/Pages/Causes.aspx

4. Miscarriages can be Prevented, Reproductive Immunology Associates. Web.
5 October 2011.

Joanna is a freelance health writer for The Mother magazine and Suite 101 with a column on infertility, http://infertility.suite101.com/. She is author of the book, 'Breast Milk: A Natural Immunisation,' and co-author of an educational resource on disabled parenting.

She is a mother of five who practised drug-free home birth, delayed cord clamping, full term breast feeding, co-sleeping, home schooling and flexi schooling and is an advocate of raising children on organic food.

Reviewed October 5, 2011
by Michele Blacksberg
Edited by Jody Smith

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We value and respect our HERWriters' experiences, but everyone is different. Many of our writers are speaking from personal experience, and what's worked for them may not work for you. Their articles are not a substitute for medical advice, although we hope you can gain knowledge from their insight.



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