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Miscarriage: Your questions answered

It’s one of the hardest topics to discuss but is incredibly common. Here’s what you need to know about miscarriage.

What is miscarriage?

A miscarriage is the loss of a pregnancy during the first 23 weeks. (NHS Choices, 2018)

What are the chances of having a miscarriage?

Most miscarriages occur at the start of pregnancy. The overall probability of a pregnancy ending in miscarriage in the UK is: 25% at four weeks; 5% at eight weeks; 1.7% at 12 weeks; and 0.5% at 16 weeks (Datayze, 2016).

More than 80% of miscarriages occur within the first 12 weeks of pregnancy. After 12 weeks, the rate decreases rapidly (Dante et al, 2013; Houry and Salhy, 2014).

What causes a miscarriage?

Good question. Despite the fact that approximately 25% of pregnancies end in a miscarriage, we’re mostly still in the dark about why (Datayze, 2016; Brann and Bute, 2017; Miscarriage Association, 2018).

Saying that, some factors that could make it more likely are:

  • Age – the risk of miscarriage is around 20% at 35 years, 40% at 40 and 75% at 45 (Andersen et al, 2000)

  • Previous miscarriages

  • Trying for a baby for a long time

  • Assisted conception

  • Low pre-pregnancy weight (BMI)

  • Regular or high alcohol consumption

  • Smoking

  • Drinking more than 200mg of caffeine a day (NHS Choices, 2018)

  • Drinking more than two units of alcohol a week

  • Feeling stressed, although there is debate over whether this might be a factor.

    (Maconochie et al, 2007; NHS Choices, 2018)

What causes a late miscarriage?

While most miscarriages happen early in pregnancy, some occur in the second or even third trimesters, which can be deeply traumatic. If it happens between 12 and 24 weeks, it is known as a late miscarriage. There are several causes:

  • Chromosome problems, such as Down’s syndrome, Edward’s syndrome and Turners syndrome (Goddijn and Leschot, 2000).

  • Structural issues like spina bifida or a congenital heart defect.

  • Antiphospholipid syndrome (APS), an immune system disorder that causes an increased risk of blood clots (NHS Choices, 2015).

  • Infections like rubella, cytomegalovirus, bacterial vaginosis, HIV, chlamydia, gonorrhoea, syphilis and malaria.

  • Anatomical – the two main anatomical causes of late miscarriage are:

  1. an unusually shaped womb, especially one that is partly divided in two

  2. a weak cervix (the neck of the womb), which may start to open as the womb becomes heavier in later pregnancy.

  • Long-term health conditions, such as diabetes, high blood pressure, lupus, kidney disease or thyroid gland problems.

    (Miscarriage Association, 2018; NHS Choices, 2018)

Can miscarriages be prevented?

No. You must never blame yourself for anything you have done. Exercising in pregnancy cannot cause a miscarriage, and neither can having sex or going to work.

The only thing you can do to reduce the risk of another miscarriage is avoiding smoking, drinking and drugs, being a healthy weight and eating a healthy diet. If you have recurrent miscarriages, doctors may prescribe medication to help.

What is an ectopic pregnancy and what are the symptoms?

An ectopic pregnancy is when a fertilised egg implants itself outside of the womb, usually in one of the fallopian tubes. The fallopian tubes connect the ovaries to the womb and if an egg gets stuck in them, it won't develop into a baby. Your health may be at risk if the pregnancy continues.

Unfortunately, it's not possible to save an ectopic pregnancy and it usually has to be removed using medicine or an operation. In the UK, around 1 in every 80 to 90 pregnancies is ectopic (NHS Choices, 2016).

An ectopic pregnancy doesn't always cause symptoms and may only be detected during a routine pregnancy scan. If you do have symptoms, they tend to develop between week four and 12 of pregnancy.

Symptoms can include a combination of:

  • abdominal pain

  • vaginal bleeding or a brown watery discharge

  • pain in the tip of your shoulder

  • discomfort when urinating.

(NHS Choices, 2016)

An ectopic pregnancy can be serious, so it's important to get advice right away. Ectopic pregnancies are treated in one of the following ways:

  • Expectant management – this is where you're carefully monitored and one of the treatments below is used if the fertilised egg doesn't dissolve by itself.

Why do some women have recurrent miscarriages?

Recurrent miscarriage means having three or more miscarriages in a row. About one in every hundred couples trying for a baby has this issue (Miscarriage Association, 2011).

If you’ve had three miscarriages in a row, you should be offered tests to try to find the cause. You might be offered tests after two early miscarriages if you are in your late thirties or forties, or if it has taken you a long time to conceive (Miscarriage Association, 2011). This should happen whether or not you already have children.

Sometimes, it’s just not possible to know why you keep miscarrying. Possible reasons are:

  • Antiphospholipid syndrome. This blood clotting problem is the most important treatable cause of recurrent miscarriage.

  • Parental chromosome abnormality. One or both parents might be carriers of a chromosome abnormality, which doesn’t manifest itself in the parent but increases the chances of a chromosome abnormality in the embryo.

  • Cervical weakness. In less than one in 100 women, there is a weakness in the cervix that allows it to dilate (open) too early.

    (Rai and Regan, 2006)

Further information

For more information on recurrent miscarriage and potential treatment options, see the leaflet of the Miscarriage Association.