It is very unlikely that you will ever know the real cause of a one-time miscarriage, but most are due to the following problems:
• ABNORMAL FETUS
The most common cause of miscarriages in the first few months is a single abnormal development in the fetus, often due to chromosomal abnormalities. “It’s not that the baby is fine one moment and suddenly dies the next,” says Professor James Walker, Professor of Obstetrics and Gynecology at the University of Leeds.
“These pregnancies fail from the beginning and were never meant to succeed.” Most miscarriages like this occur at eight weeks, although bleeding may not start until three or four weeks later, which is worth remembering in subsequent pregnancies. “If a scan at eight weeks shows a healthy heartbeat, you have a 95 per cent chance of having a successful pregnancy,” says Professor Walker.
• HORMONAL FACTORS
A hormonal problem could cause a sporadic miscarriage and never be a problem again. However, a small number of women who have long cycles and irregular periods may experience recurrent miscarriages because the lining of the uterus is too thin, making implantation difficult.
Unfortunately, hormonal treatment is not very successful.
“There used to be a trend in favor of progesterone treatment, but trials show that it doesn’t really work,” Professor Walker warns. “There is evidence that HCG (human chorionic gonadotropin, a hormone released in early pregnancy) injections can help, but it is not the answer for everyone.” Treatment should be started as soon as pregnancy is confirmed, around four or five weeks.
• AGE
For women over 40, one in four women who become pregnant will suffer 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 recurrent miscarriages suffer from lupus or a similar autoimmune disorder that causes blood clots to 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. “A negative test does not mean that a woman is fine,” warns Roy Farquharson, a gynecologist specializing in early pregnancies. Liverpool Women’s Hospital unit.
“Pregnancy can often be a trigger for these disorders, 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 clot formation. – A recent trial also showed that women do equally well in either. “We have a 70 percent live birth rate in women treated for these disorders,” says Dr. Farquharson , “which is excellent.”
• OTHER CAUSES
While uterine abnormalities, such as fibroids, can cause miscarriage, many women have no problems carrying the pregnancy to term. An incompetent cervix can also cause a miscarriage around 20 weeks.
While this can be treated with a special suture in the cervix, trials suggest this is not particularly successful, although it may delay delivery by a few weeks. Genetic and chromosomal abnormalities, which can be detected by blood tests, can also cause 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 taken from the developing embryo and analyzed for the genetic defect. Then, only healthy embryos are replaced in the uterus.
It is an expensive and stressful procedure, and pregnancy rates tend to be quite low, but for some it is preferable to repeated miscarriages or a genetically abnormal baby.