What is it?
Miscarriage refers to the loss of a pregnancy before the baby is mature enough to survive on its own outside the womb. It is also referred to as spontaneous abortion to distinguish it from termination of pregnancy (induced abortion).
How common is it?
It is a common complication of pregnancy. Indeed, some doctors believe that most early pregnancies end in miscarriages before women even realise they are pregnant. Research has shown that a lot of so-called ‘late periods’ are actually very early miscarriages. About 1 out of every 10 confirmed pregnancies will end as a miscarriage and most of these (3 out of every 4) occur in the first three months of pregnancy.
Types of miscarriage
The term miscarriage is used to describe a variety of clinical states including:
- Anembryonic gestation – this was previously known as blighted ovum and refers to a miscarriage that occurs very early before the baby has actually formed in the womb.
- Threatened miscarriage – this refers to any bleeding from the vagina during the first half of pregnancy after the baby has formed and is alive.
- Inevitable miscarriage – this refers to the situation where a threatened miscarriage proceeds beyond the point where the pregnancy can be saved. It is usually characterised by heavier vaginal bleeding and lower abdominal and pelvic pain.
- Incomplete miscarriage – this refers to situations in which some of the baby is passed through the neck of the womb while other parts (like the afterbirth) are retained within the womb.
- Missed abortion– this refers to situations where the pregnancy stops to develop because the baby has died in the womb.
What causes miscarriage?
Although most miscarriages occur because of problems with the pregnancy, or that develop in the baby or mother, it is often impossible or impractical to find out what those problem are. Most early miscarriages are believed to be due to abnormalities of chromosomes (the materials that carry our genes). Some miscarriages occur because of weakness of the neck of the womb (cervical incompetence) and these typically occur between 14 and 26 weeks. Unfortunately, some healthy pregnancies miscarry following tests (like amniocentesis and CVB) that are done to study the baby’s chromosomes.
The risk of miscarriage increases with the woman’s age. About 1 in 4 pregnancies in women aged 40 years end in miscarriage, often because of chromosomal abnormalities. Some women have higher risks of miscarriage than others. Women with more than one previous miscarriage have higher risks of further miscarriages. Other factors that increase this risk include smoking, medical conditions (like diabetes), some blood disorders that increase blood clotting, uterine fibroids (swellings in the womb), and some infections. Abnormalities of the shape of the womb can also cause miscarriages (usually late miscarriages).
How are miscarriages recognised?
Women sometimes have no idea they are undergoing a miscarriage and an early miscarriage may be assumed to be a late menstrual period. A miscarriage may be discovered only during routine antenatal examination when the baby’s heartbeat is neither heard nor seen on ultrasound scans (delayed miscarriage). Miscarriages are usually recognised by bleeding from the vagina that may initially be painless (threatened miscarriage). The onset of lower abdominal pain may indicate that the pregnancy is not going to continue (inevitable miscarriage). Medical workers can safely make these distinctions and so it is advisable for women who believe they are having a miscarriage to seek medical help as soon as possible.
Can anything be done to prevent a miscarriage?
Unfortunately most miscarriages are not preventable because they are due to chromosomal abnormalities or their cause is unknown. Risk factors like smoking, diabetes, fibroids or structural abnormalities of the womb may need to be treated. Placing a stitch around the neck of the womb (cervical cerclage) at about 14 weeks of pregnancy may help to prevent miscarriages that are due to weakness of the neck of the womb (cervical incompetence).
The Miscarriage Association
C/o Clayton Hospital
West Yorkshire WF1 3JS
Tel. 01924 200 799