Between one in four and one in five of all pregnancies ends in miscarriage. That means that somewhere between 200,000 and 250,000 conceptions every year end that way. They involve pain, frustration, distress and fear for the women involved and their partners.
A woman has about a one in five chance of having one miscarriage, a one in 25 chance of having a second, and roughly a one in 125 chance of losing a baby that way for a third time, according to Dr Justin Clark, a consultant obstetrician and gynaecologist at Birmingham Women's Hospital. William Hague revealed last night that his wife, Ffion, had had "multiple miscarriages", including one this summer.
Most miscarriages happen in the first 12 to 14 weeks of pregnancy. A woman's risk of having one goes down to about one in 100 during the second trimester of her pregnancy.
It is only when a woman suffers three that doctors intervene. When that happens, she will be referred to a gynaecologist or specialist miscarriage clinic for further investigation. Women then usually undergo blood tests to see if they have any underlying medical problems that may explain why the pregnancies are not progressing, including "sticky blood", or antiphospholipid syndrome in medical speak.
Age and body mass index (BMI) are two significant key risk factors for repeated miscarriage, Clark says: "Once a woman goes beyond 37 her fertility starts to reduce quite a lot and her egg quality isn't as good."
The higher a woman's BMI, the greater her risk of suffering either one or a repeated miscarriage. Having a chronic long-term condition, such as diabetes, is another risk factor.
"In general a woman who has one or more miscarriages will ultimately go on to have a successful pregnancy, even after repeated miscarriages," Clark says. "But there are some sad cases of women having as many as 15 miscarriages and never having a baby." Recurrent miscarriage responds better to treatment when the losses occur in the first trimester.
There are five main causes of women losing a baby in this way, according to the Miscarriage Association: genetic, hormonal, immunological, infection or anatomical.
About half are due to genetics, and many of those occur around the time when the egg and sperm meet to form the embryo.
Hormonal problems can include, for example, the embryo failing to burrow into the lining of the womb. Anatomical problems, meanwhile, include women with a very small or heart-shaped uterus.
