Miscarriage is the term given to any pregnancy that is lost before the 24 week mark. It occurs in around 50 per cent of conceptions, although the vast majority of these happen around two weeks after conception.
This means that many women are totally unaware of their miscarriage as it presents itself as a normal, or slightly delayed, period.
From this point onwards, around 15 per cent of miscarriages are clinically recognised. Of this 15 per cent, approximately 98 per cent will happen within the first 13 weeks of pregnancy.
Miscarriage can happen to anyone, but there factors that can increase risk. This includes smoking or drinking high levels of alcohol; or suffering from medical conditions like diabetes. Contracting a virus such as rubella or a sexually transmitted infection can also result in miscarriage.
It is often impossible to detect exactly why a miscarriage occurs, and is normally attributed to a chromosomal abnormality in the foetus. However, late miscarriages can be caused by problems with the placenta or the woman's uterus or cervix.
Signs of impending miscarriage include heavy bleeding and lower abdominal pain. In later miscarriages, a woman's waters may break which will signal the onset of a miscarriage. Many women also 'just know'.
In some situations, a miscarriage will occur but there will be no sign. This is usually detected by a routine ultrasound scan, and if this has happened the woman will need to undergo a medical procedure to empty the womb.