ABC Health & Wellbeing

Fact File

Miscarriage

by Heather Catchpole

Miscarriage is more common than we think, and for some, it can be a very traumatic experience. Yet we still don't understand all the reasons why it happens.

Published 08/11/2006

[Image source: iStockphoto]

• What is it?
• Signs of miscarriage
• Investigating miscarriage
• Risk factors
• Management
• After a miscarriage
• Late miscarriage
• Recurrent miscarriage
• Grief and trauma
• Getting pregnant again
• More info

Miscarriage is the loss of a pregnancy before 20 weeks gestation. In fact, it usually occurs before 12 weeks.

About one in seven recognised pregnancies will miscarry and about one in three women will experience a miscarriage during their reproductive life. However, miscarriage is actually much more common than we previously thought. Sensitive urine tests now detect pregnancy very early. As a result we now know that up to 60 per cent of all conceptions miscarry, many before a period is missed and before the woman even knows she's pregnant.

Age plays a big role in miscarriage with the chance of losing a recognised pregnancy being about one in ten in a 20-year-old, one in seven in a 30-year-old, one in three in a 40-year-old, and one in two in a 45-year-old.

Miscarriage can be a difficult and traumatic experience for some women. For others, it may happen very early in the pregnancy (as discussed above) and may not even be noticed. Pregnancy isn't always straightforward. And when you think about what's happening to create a new life, it seems pretty extraordinary that it works at all.

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What is it?

Miscarriages can occur for a number of reasons, and not all of them are understood.

The most common cause of miscarriage is a chance chromosomal or other genetic abnormality. At conception the DNA from the father's sperm combines with the DNA from the mother's egg. Mistakes can happen when the DNA in the egg or sperm splits or copies itself, and this can result in an excess or deficit of chromosomes (or chromosome pieces) in the embryo. These embryos are not normal, and miscarriage is nature's way of taking care of the problem.

Sometimes the pregnancy fails because there's no developing embryo in the pregnancy sac (known as a blighted ovum). At other times the embryo is there – it can be seen on ultrasound – but its heart has stopped beating (known as a missed miscarriage). In about two per cent of pregnancies the embryo does not implant in the uterus, but in the fallopian tubes. This is known as ectopic pregnancy. It can be associated with life-threatening bleeding and it usually needs to be removed surgically or by using medication.

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Signs of miscarriage

Any vaginal bleeding during pregnancy is called a threatened miscarriage. However 25 per cent of women who go on to have a baby have experienced some vaginal bleeding. If you experience vaginal bleeding you should see your doctor.

Another possible symptom of miscarriage is cramping or period-like pain but again, if you experience this, it does not necessarily mean the pregnancy will be lost.

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Investigating miscarriage

Ultrasound is the most important tool for diagnosing miscarriage. In early pregnancy a vaginal ultrasound – which is completely safe – is more accurate than an abdominal ultrasound because the vaginal probe can get very close to the uterus and see the pregnancy more clearly.

If a woman has a 28-day cycle, by five weeks after her last period a small gestational sac can often be seen inside the uterus and by six weeks, a small embryo with a heartbeat will usually be present.

However, because women sometimes ovulate later than they think, the absence of these changes doesn't always mean miscarriage is occurring. Another ultrasound a week later may be needed. Nevertheless, if the gestational sac is quite big, but there is no embryo, or if the embryo is quite big but there is no heartbeat, or if there has been no growth over a week, miscarriage is very likely.

A blood test for the pregnancy hormone human chorionic gonadotrophin (HCG), is sometimes used in addition to ultrasound. In a normal pregnancy the level of HCG doubles approximately every 48 hours. If the HCG is rising more slowly or if it is falling, a failed pregnancy (or less commonly an ectopic) is likely.

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Risk factors

The vast majority of miscarriages happen early and are simply bad-luck chance events where the pregnancy is not quite right and nature takes care of it. It's important to note that a woman's actions play essentially no role in a miscarriage. She cannot make a miscarriage happen by exercising, using an electric blanket, having sex, eating spicy food or working at a computer screen. Similarly, there is generally nothing she can do to prevent it happening.

That said, the following are thought to probably increase the risk of miscarriage and may need to be modified:

• Smoking. Smoking reduces the supply of oxygen to the placenta. Women who smoke are at increased risk of ectopic pregnancy, miscarriage, oxygen-starved baby and pre-term delivery.
• Alcohol. Alcohol intake in excess of two standard drinks a days has been linked to miscarriage.
• Caffeine. The role of caffeine in miscarriage is controversial. After initial evidence that caffeine was linked to birth defects and miscarriage, further research failed to confirm the link. However, caffeine is metabolised by the same enzymes that metabolise the hormones of pregnancy. So, in theory, as little as one strong cup of coffee a day could reduce the chances of successful implantation of an embryo in the uterus. As a result, most authorities recommend limiting caffeine intake to one cup of strong coffee or tea a day.
• Obesity. Women who are obese (that is with a body mass index or BMI greater than 30) are twice as likely to miscarry as women in the normal weight range.

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Management

Sometimes the best management of miscarriage is to do it naturally, letting the uterus empty itself over days or weeks. At other times you might prefer (or your midwife/doctor might recommend) a dilatation and curettage (D&C also known as a curette). This is carried out under a light anaesthetic, and involves gently cleaning any clots or pregnancy products from the uterus. Either option – waiting or having a curette – might be appropriate and both have advantages and disadvantages. Your midwife or doctor will be happy to discuss these with you.

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After a miscarriage

After a miscarriage you may experience bleeding (often on and off) for up to two weeks. If the bleeding is very heavy or continues for longer than a fortnight or has an unpleasant odour you should see your doctor immediately. Similarly, if at any time you have a fever or feel unwell in any way, you should have an urgent check-up.

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Late miscarriage

Uncommonly, miscarriage occurs between 12 and 20 weeks. This is termed late miscarriage and may be associated with more bleeding and pain than earlier pregnancy loss. If the foetus has died but remains within the uterus, medication is given to make the uterus empty itself or a curette is undertaken. If the foetus has been passed but the placenta remains inside the uterus, a curette may also be required.

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Recurrent miscarriage

Since most miscarriages happen by chance, one miscarriage only slightly lowers your probability of having a successful pregnancy the next time around. However, two per cent of women will have two miscarriages in a row, while 0.5 - 1 per cent will have three or more miscarriages in a row – known as recurrent miscarriage. Of these, about half will be by chance and half will have an underlying cause. Review by your doctor or in a special recurrent miscarriage clinic is worthwhile in this situation.

Recurrent miscarriage can happen for a number of reasons. In some cases there is a repeated chromosomal abnormality passed down from one or other parent. Or there can be complications from blood clots blocking off the placenta, or the shape of the uterus or cervix not allowing the foetus to develop properly or causing it to deliver early. Tests and treatments are available for many of these problems.

However, it must be pointed out that recurrent miscarriage is poorly understood, and in 50 per cent of cases there is no explanation despite detailed investigation. This is a traumatic and frustrating experience. Counselling is available and recurrent miscarriage clinics can monitor subsequent pregnancies. Frequent monitoring has been shown to result in more successful pregnancy outcomes next time.

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Grief and trauma

Feelings of grief can often accompany a miscarriage. It is natural to feel loss, sadness, anger, and even guilt, despite the fact that the end result is out of your hands. There are several organisations that can help with counselling and information on miscarriage, including SIDS and kids, and the Stillbirth and Neonatal Death Support Group (SANDS). You can also ask your doctor about miscarriage counselling. If you have been in contact with a hospital during your experience, hospital social workers can also provide counselling.

It's important to have the support of your partner, friends and family. Talk to people to let them know if and when you would like to discuss your experience. You may experience negative feelings when encountering other pregnant women or new babies. This is normal and will pass. There is no right way to deal with miscarriage. It affects every woman and her partner in a different way and for a different length of time.

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Getting pregnant again

How long you wait before deciding whether to get pregnant again is a personal choice. Some people may want to try again immediately, while others may prefer to wait. Your ovaries will generally release another egg two weeks after a miscarriage, so if you do want to wait it is important to look into contraception straightaway.

Some doctors recommend waiting for one cycle before trying again, and there is a slightly higher chance of miscarriage if the conception takes place before this time. In any miscarriage it's important to remember that it is likely that your next pregnancy will proceed normally, even if you have experienced several miscarriages.

All women planning pregnancy, whether or not they have had a miscarriage, should be taking folic acid to reduce the chance of abnormalities and iodine to protect the baby's brain development and IQ. The dose of folic acid is 500 micrograms and iodine is 200 micrograms every day. Both should be started at least one month but ideally three months prior to conception and continued through at least the first three months of pregnancy.