Causes

• Age: If you are over 40 yrs old, there is a 50% chance of a miscarriage.
• Miscarriages may also be more common if the father is older.
• Antiphospholipid syndrome (APS): APS (a syndrome that makes your blood more likely to clot).
• Thrombophilia: Thrombophilia (blood clotting) may cause recurrent miscarriage and in particular late miscarriages.
• Genetic factors: In about 2–5 in 100 couples (2–5%) with recurrent miscarriage, one partner will have an abnormality on one of their chromosomes (the genetic structures within our cells that contain our DNA and the features we inherit from our parents). Although this may not affect the parent, it can sometimes cause a miscarriage.
• Weak cervix: Weakness of the cervix is known to be a cause of miscarriage from 14 to 23 weeks of pregnancy.
• Developmental problems of the baby: Some abnormalities of the baby may lead to a miscarriage but are unlikely to be the cause of recurrent miscarriage.
• Infection: Any infection that makes you very unwell can cause a miscarriage.
• The shape of the uterus: It is not clear how much an abnormally shaped uterus contributes to recurrent miscarriage or late miscarriages. However, minor variations do not appear to cause miscarriage.
• Diabetes and thyroid problems: Diabetes or thyroid disorders can be factors in miscarriages. They do not cause recurrent miscarriage, as long as they are treated and kept under control.
• Immune factors: It has been suggested that some women miscarry because their immune system does not respond to the baby in the usual way. This is known as an alloimmune reaction. There is no clear evidence to support this theory at present. Further research is needed.