Miscarriage risk increases with age. It is highest if you are over 40 and miscarriages may also be more common if the biological father is over 40.

Women are born with all the egg cells they will ever have. The older you are, the older your egg cells and the more likely they are to carry a genetic error. There seem to be age-related issues with male sperm too. But even in your early 40s with up to three miscarriages, you are still more likely to have a healthy pregnancy than another miscarriage.

Risk increases with the number of miscarriages you have had in the past. But even after three miscarriages, most people will have a healthy pregnancy next time. 

The risk of miscarriage increases if:

• you have miscarried before, especially after three miscarriages
• it has taken more than a year to conceive
• you are pregnant with twins or more.

Black and Black mixed heritage women have a 43% higher risk of miscarriage compared to white women. They also have an increased risk of stillbirth and are more likely to suffer poor maternal outcomes. Researchers are working to find out why this is and whether there are any actions that could reduce the risk.

If you already are what’s considered a healthy weight (BMI between 19 and 25), there’s no need to change.  If not, your GP or practice nurse may be able to advise and support you.  If you smoke, they will be able to support you in stopping. Experts agree that it is best to limit the amount of caffeine you drink (tea, coffee or caffeinated soft drinks) to two cups or glasses a day.  They also advise either not to drink alcohol at all or to avoid drinking regularly or to excess.

Some medicines like Ibuprofen may increase miscarriage risk.  If you take regular prescribed medicine, including some anti-depressants, it’s best to ask your doctor which are safe in pregnancy and not just stop them yourself.

Overall, research suggests that there is a link between stress and miscarriage –miscarriage or being pregnant after loss can cause stress.  But there is no clear evidence that stress causes miscarriage.  Your risk of miscarriage may be higher if you are exposed to workplace hazards such as toxic chemicals, solvents, lead or radiation. Research also suggests that working nights, shifts and/or long hours are linked to increased miscarriage risk, but again, don’t necessarily cause it.

Mild infections like coughs and colds are not harmful in pregnancy, but very high fevers and some serious infections can cause or increase the risk of miscarriage. If an infection causes miscarriage, it tends to happen only once because your body will then become immune to the infection.

Sometimes an infection of the vagina or uterus can cause late miscarriage (from 14 weeks). The infection may cause the baby to die in the uterus; or it may make your waters break prematurely. Doctors can test for this kind of infection and treat it if necessary.  Depending on the infection, your partner may need treatment to avoid re-infecting you.

This is caused by eating unpasteurised cheese and other dairy products, pâté or uncooked smoked fish. It isn’t usually harmful to non-pregnant women but it can be a cause of late miscarriage.

This infection is usually sexually transmitted; but a rare form called Chlamydia psittaci, can be caught from touching infected sheep or cattle, particularly during lambing or calving. Chlamydia can lead to miscarriage, ectopic pregnancy or premature labour; it can also harm your fertility if left untreated.

This is a parasitic infection sometimes carried by cats. It can be caught through contact with used cat litter, with contaminated soil, or through eating poorly cooked contaminated meat.

This is a viral infection, which is sometimes called ‘slap-cheek’. Although it can cause miscarriage, most women who are infected have a normal pregnancy.

Some other infections are especially harmful in pregnancy although they don’t usually cause miscarriage. These include cytomegalovirus (CMV), rubella (German measles), genital herpes and HIV.

Thyroid disease or high levels of thyroid stimulating hormone (TSH) or thyroid antibodies may increase miscarriage risk. If you are found to have either diabetes or thyroid disease, you will be supported to control this as well as possible before your next pregnancy.

Abnormal levels of the hormone prolactin may increase the risk of miscarriage.  There is no recommended treatment if you have a prolactin imbalance, but you might be offered treatment as part of a clinical trial.

Many people ask about treatment with progesterone supplements as a way to prevent miscarriage. Research has shown that for women with bleeding in early pregnancy and a history of recurrent (multiple) miscarriages, progesterone treatment slightly reduced their chances of miscarrying. This treatment is now recommended and early pregnancy units will discuss with women when they might be offered it.