Miscarriage is the natural or spontaneous end of a pregnancy at a stage where the prenate is incapable of surviving, generally defined in humans at prior to 20 weeks of gestation. Miscarriage is the most common complication of early pregnancy.
Sadly, miscarriage is a common event. Although it's difficult to give an exact figure, about 15 per cent of known pregnancies end in miscarriage.
Often, a woman miscarries before she realises she's pregnant. Perhaps as many as three-quarters of all fertilised eggs are lost in the very earliest stages of pregnancy. About 98 per cent of women who miscarry do so in the first 13 weeks but occasionally, a woman will miscarry much later.
What causes a miscarriage?
Probably at least half of all miscarriages in the first trimester of pregnancy are the result of chromosomal abnormalities that prevent the baby from developing normally. Later miscarriages - after 20 weeks - may be the result of an infection or an abnormality of the uterus or placenta, or a weak cervix, sometimes called an "incompetent cervix" that is not strong enough to keep the womb tightly closed until the baby is ready to be born.
Doctors aren't able to pinpoint the reason for most early miscarriages but it seems that a foetus which is abnormal in some way, tends to miscarry.
Unfortunately, two of the tests - amniocentesis and chorionic villus sampling (CVS) - used to detect abnormalities in babies can also cause miscarriage. Amniocentesis, generally performed between the 15th and 18th weeks of pregnancy, results in miscarriage for around one per cent of women.
The most obvious signs of miscarriage are period-like pains and heavy bleeding, which may include blood clots. However, women can miscarry without even knowing, especially early in pregnancy. Many women mistake a miscarriage for a late period.
Some miscarriages are discovered only during a routine antenatal visit, when the doctor or midwife cannot find the baby's heartbeat.
What increases the risk of miscarriage?
Various circumstances increase the risk of miscarriage, including:
- Age. Women older than age 35 have a higher risk of miscarriage than do younger women. Paternal age also may play a role. In a 2006 study, women whose partners were age 40 or older had a higher risk of miscarriage than did women whose partners were younger than age 25.
- Previous miscarriages. The risk of miscarriage is higher in women with a history of two or more previous miscarriages. After one miscarriage, your risk of miscarriage is the same as that of a woman who's never had a miscarriage.
- Chronic conditions. Women with certain chronic conditions, such as diabetes or thyroid disease, have a higher risk of miscarriage.
- Uterine or cervical problems. Certain uterine abnormalities or a weak or unusually short cervix may increase the risk of miscarriage.
- Smoking, alcohol and illicit drugs. Women who smoke or drink alcohol during pregnancy have a greater risk of miscarriage than do nonsmokers and women who avoid alcohol during pregnancy. Illicit drug use also increases the risk of miscarriage.
- Caffeine. The evidence linking caffeine consumption and miscarriage is inconclusive. Because of the unknowns, your doctor may recommend avoiding caffeine during the first trimester and limiting the amount of caffeine you drink to less than 300 milligrams a day during the second and third trimesters.
- Invasive prenatal tests. Some prenatal genetic tests, such as chorionic villus sampling and amniocentesis, carry a slight risk of miscarriage.
Moving toward healing
Many women who experience pregnancy loss go on to have successful pregnancies. Once the pain of your grief subsides, you and your partner can talk about whether to attempt another pregnancy and, if so, when you'd like to try again.
Another pregnancy may yield feelings of sadness for your earlier loss - but it may also inspire hope for the future.
Chat to other women on the Essential Baby forums about miscarriage.
