Miscarriage is most likely to occur in the first 12 weeks of pregnancy. Indeed, many happen in the first six weeks, often without a woman even knowing she was pregnant. Within those first six weeks, around one in every six pregnancies will end in miscarriage. By eight weeks that chance of miscarriage has dropped significantly, to around one in 16 pregnancies.
Beyond the magical 12 weeks point, when the placenta is fully formed, only one in 100 pregnancies ends in miscarriage. For more about late miscarriages.
The majority of miscarriages are caused by abnormalities in the developing foetus. This is when the foetus does not develop normally due to faulty chromosones. The body recognises that the foetus will not be able to grow into a healthy baby and will be unable to survive and causes a miscarriage to prevent the pregnancy going further.
For this reason, once you’ve past your 12th week, where most of the initial development happens, you are far less likely to miscarry.
If you have had a miscarriage before, you are statistically more likely to miscarry again but this is often due to underlying medical conditions that may have caused previous miscarriages such as placenta praevia and incompetent cervix. Find out more about the chances of miscarriage happening again. It is not until you have had two or more miscarriages that your chances of a successful pregnancy decrease and it may be worth speaking to your GP about possible causes.
Although miscarriage is fairly common, occuring in one in four pregnancies, take heart that the majority of women go on to have healthy pregnancies in the future.