Miscarriage is very common. There are many things that can cause a miscarriage. But in a lot of cases, it is not possible to say why a miscarriage happens.
The causes of miscarriage are often not in your control. Most miscarriages are not caused by something you did or did not do.
Most miscarriages happen because of chromosome problems in the fetus. But there are other causes and risk factors.
Chromosome problems
Chromosomes are blocks of DNA with instructions for your baby’s development.
Sometimes something goes wrong at the point of conception and the fetus gets too many or too few chromosomes. As a result, it cannot develop properly. This can lead to miscarriage.
Health conditions
Some health conditions can increase your risk of miscarriage, especially if the condition is not treated or well controlled.
These include:
- diabetes
- thyroid disorders
- high blood pressure
- lupus - immune system disease
- kidney disease
- antiphospholipid syndrome (APS) - an immune system problem that can cause your blood to clot
Medicines
Some medicines can increase your risk of miscarriage.
Check with your GP, midwife or a pharmacist before taking any medicine during pregnancy.
Other risk factors
Other things may increase your risk of miscarriage, such as:
- your age - you are age 35 or older
- you've had previous miscarriages
- your ethnicity - you have a Black African or Caribbean background
- you are significantly underweight, have excess weight or have obesity
- you drink a lot of alcohol in pregnancy
- you smoke or use drugs
Other risk factors for late miscarriages
Other risk factors for late miscarriages include:
- problems with the placenta or umbilical cord
- certain infections - such as rubella (german measles)
- anatomical or structural problems with your womb or cervix (neck of the womb)
Problems with your womb or cervix can include:
- an irregular-shaped womb
- fibroids (non-cancerous growths in your womb) - this depends on the size and location of the fibroids
- a weak cervix that opens too early in pregnancy