Rebecca Adlington reveals she’s learnt to talk about her late daughter Harper without ‘bursting into tears’ after her heartbreaking miscarriage

It is highly unlikely that you will ever know the actual cause of a single miscarriage, but in most cases the following problems are the cause:

• ABNORMAL FETUS

The most common cause of miscarriage in the first few months is a one-off abnormal development of the foetus, often due to chromosomal abnormalities. ‘It’s not like the baby is fine one minute and suddenly dies the next,’ says Professor James Walker, professor of obstetrics and gynaecology at the University of Leeds.

‘These pregnancies are failing from the start and were never meant to succeed.’ Most miscarriages like this happen in the eighth week, although bleeding can start as late as three or four weeks later, which is worth remembering for future pregnancies. ‘If a scan shows a healthy heartbeat in the eighth week, you have a 95 per cent chance of a successful pregnancy,’ says Professor Walker.

• HORMONAL FACTORS

A hormonal blip can cause a sporadic miscarriage and never be a problem again. However, a small number of women with long cycles and irregular periods may have repeated miscarriages because the lining of the uterus is too thin, making implantation difficult.

Unfortunately, hormone treatment is not very successful.

‘There used to be a trend for progesterone treatment, but studies show that it really doesn’t work,’ Professor Walker warns. ‘There is some evidence that injections of HCG (human chorionic gonadotrophin, a hormone released in early pregnancy) can help, but it’s not for everyone.’ Treatment should be started as soon as pregnancy is confirmed, at around four or five weeks.

• AGE

One in four women over the age of 40 who become pregnant will have a miscarriage. [One in four women of all ages miscarry, but these figures include women who don’t know that they are pregnant. Of women who do know that they’re pregnant, the figure is one in six. Once you’re over 40, and know that you’re pregnant, the figure rises to one in four]

• AUTOIMMUNE BLOOD DISORDERS

About 20 percent of women who have recurrent miscarriages have lupus or a similar autoimmune disease in which blood clots form in the developing placenta.

A simple blood test, which may need to be repeated several times, can reveal whether this is the problem or not. ‘One negative test does not mean a woman is fine,’ warns Mr Roy Farquharson, gynaecologist and head of early pregnancy at Liverpool Women’s Hospital.

Often pregnancy can be a trigger for these conditions, so testing should be done as soon as possible,’ he adds. But it can be easily treated with low-dose aspirin or heparin injections, which help thin the blood and prevent clots from forming – a recent study also showed that women do equally well on both. ‘We have a 70 per cent live birth rate in women treated for these conditions,’ says Dr Farquharson, ‘which is excellent.’

• OTHER CAUSES

Although uterine abnormalities, such as fibroids, can cause miscarriage, many women have no trouble carrying a pregnancy to term. An incompetent cervix can also cause miscarriage around the 20th week.

Although this can be treated with a special suture in the cervix, studies show that this is not particularly successful. It can delay labor by a few weeks. Genetic and chromosomal abnormalities, which can be detected by blood tests, can also lead to recurrent miscarriages in a small number of couples.

A procedure known as preimplantation genetic diagnosis can help. After in vitro fertilization (IVF), a single cell is removed from the developing embryo and tested for the gene defect. Only healthy embryos are then transferred back into the uterus.

It is an expensive and stressful procedure, and the chances of pregnancy are generally low. However, for some it is preferable to repeated miscarriages or a genetically abnormal baby.