Antiphospholipid Syndrome (APS)
This blood clotting problem is the most important treatable cause of recurrent miscarriage. It happens when your immune system makes abnormal antibodies that attack fats called phospholipids in your blood. This makes the blood more ‘sticky’ and likely to clot, which is why APS is sometimes called ‘sticky blood syndrome’. It is also known as ‘Hughes syndrome’ after the expert who named it.
Other Blood Clotting Problems
Some inherited blood clotting disorders can cause recurrent miscarriage, particularly after 14 weeks. These include factor V Leiden, factor II (prothrombin), gene mutation and protein S deficiency.
About half of all miscarriages happen because the baby’s chromosomes are abnormal. This is not usually an inherited problem: it happens when the egg and sperm meet or soon after the egg is fertilised. The older you are the more likely this is to happen. Much less commonly (in less than five in one hundred couples with recurrent miscarriage), one partner carries a chromosomal defect called a ‘balanced translocation’. This doesn’t cause a problem for the parent, but it can be passed on to the baby as an ‘unbalanced translocation’. This means that some genetic information is duplicated and some is missing.
Cervical weakness (also known as ‘Incompetent Cervix’)
Your cervix is a kind of ‘gateway’ between the uterus and vagina, which normally dilates (widens) during labour to allow the baby to be born. Some women – probably less than one in a hundred – have a weakness in the cervix that allows it to dilate too early. This is a known cause of late (second trimester) miscarriage.
There are treatments and tests available. It is recommended that you and your partner be seen by expert health professionals, ideally at a special recurrent miscarriage clinic. Your doctor should know whether there is one in your area and organise a referral.
Causes of Miscarriage
The main causes of miscarriage are thought to be:
This is when the baby doesn’t develop normally right from the start and cannot survive. This is the cause of more than half of all early miscarriages.
Women with hormonal irregularities may find it harder to get pregnant; and when they do, are more likely to miscarry.
Problems in the blood vessels that supply the placenta can lead to miscarriage, especially if the blood clots more than it should.
Minor infections like coughs and colds are not harmful. But very high fevers and some illnesses or infections, such as German measles, may cause miscarriage.
There are three main anatomical causes of miscarriage:
- If the cervix (the bottom of the uterus) is weak, it may start to open as the uterus becomes heavier in later pregnancy and this can cause a miscarriage.
- If the uterus has an irregular shape, there may not be enough room for the baby to grow.
- Large fibroids (harmless growths in the uterus) may cause miscarriage in later pregnancy.