Mother and Baby

Miscarriage facts: the signs and causes of a miscarriage

Miscarriage facts: the signs and causes of a miscarriage

Miscarriage is, sadly, an all-too-common event – about one in every four pregnancies ends this way according to the Miscarriage Association. It’s never an easy thing to go through, but as part of the healing process, it can help to understand exactly what has happened.

The pain, grief and sense of loss that comes from having a miscarriage can be indescribable, and it’s often hard to move past such a difficult experience – especially when it comes to being around friends with children and even trying to become pregnant again.

As well as leaning on your support network at such a difficult time, it can perhaps also help to understand the experience you’ve been through – and begin the healing process.

What is a miscarriage?

It’s the name given when a pregnancy ends before 24 weeks. If you miscarry in the first 12 weeks of pregnancy (the first trimester), it is called an ‘early miscarriage’ – around three quarters happen in this initial stage when some women don’t yet realise they’re pregnant. A miscarriage after the 12-week mark is called a ‘late miscarriage’.

The symptoms and signs of miscarriage

The most common symptom of miscarriage is vaginal bleeding. You’d either have a light brown discharge, or heavy bleeding and bright red blood that gradually reduces to a stop after a few days.

Light vaginal bleeding during your first trimester of pregnancy is common, so try not to automatically jump into panic mode. Sill contact your maternity team or early pregnancy unit at your local hospital immediately, just to be sure everything’s ok.

If, however, you experience heavy and painful bleeding, severe abdominal pain and are feeling faint and light-headed you should immediately go to your nearest A&E department.

Other symptoms include cramping and pain in your lower abdomen, as well as discharge of fluid or tissue from your vagina. Again, you need to contact your doctor straight away if you experience this.

What causes a miscarriage?

The NHS estimates that up to two thirds of early miscarriages are related to chromosome abnormalities. A fetus needs to have 23 chromosomes (blocks of DNA-carrying genes) from the father’s sperm and 23 from the mother’s egg to make a full set.

Abnormalities often happen when a baby receives the wrong number of chromosomes. Problems with the development of the placenta or the fetus developing outside the womb can also lead to a miscarriage.

Diana Hamilton-Fairley, consultant in obstetrics and gynaecology, and advisor to the Miscarriage Association says, 'It’s nothing inherited, just bad luck and no-one’s fault. Part of the process has gone wrong though we’re unlikely to know what.’

A late miscarriage – after 12 weeks – could be down to health problems such as diabetes, infection, severe high blood pressure and problems with the cervix, uterus or placenta. But, pinning down exactly why you’ve miscarried can be tricky.

Other factors affecting your chance of miscarriage include smoking, alcohol and excessive caffeine

What affects your chances of having a miscarriage?

Research suggests that age does play a role. Women under 30 have a one in 10 chance of having a pregnancy end in miscarriage, while women between 35 and 39 have a one in five chance, according to the NHS. If you are an older mum-to-be, however, you still have a very good chance of delivering a healthy baby to term.

Other factors affecting your chance of miscarriage include smoking, alcohol and excessive caffeine. Doctors recommend no more than 200mg of caffeine in a day (that’s around two mugs of instant coffee) and to limit yourself to two units of alcohol a week (equivalent to a small glass of wine).

The main thing to remember in any case is that feeling grief, shock and pain is completely normal, so don’t be afraid to take the time you need and accept the support around you.

The search for the causes of miscarriage

Most parents never find out why their miscarriage happened. The animation below explains how Tommy's, the largest charity funding research into miscarriage, stillbirth and premature birth, is working to improve understanding of the biological processes at work, and finding ways to prevent miscarriages not caused by chromosomal abnormalities.

What does a miscarriage look and feel like?

In many cases you won’t know you've had a miscarriage – it happens before you even know you’re pregnant.

If you’ve had your pregnancy confirmed then bleeding – ranging from brownish discharge to heavy bleeding – and period-like pain are common signs. Sometimes women no longer feel sick and their breasts are no longer tender.

‘If you’ve any of those symptoms you mustn’t assume it’s miscarriage,’ Diana says. ‘It could be a little blood from the placenta or, if you’ve recently had sex it could be blood from the cells on the surface of the cervix that are more delicate in pregnancy.

‘And nausea and breast tenderness tend to disappear around 12 weeks anyway.’

How long does a miscarriage last?

A woman early in her pregnancy may have a miscarriage and only experience bleeding and cramping for a few hours. But another woman may have miscarriage bleeding for up to a week. The bleeding can be heavy with clots, but it slowly tapers off over days before stopping, usually within two weeks.

The length of a miscarriage differs for every woman, and depends on different factors, including: how far along you were in the pregnancy, whether you were carrying multiples and how long it takes your body to expel the fetal tissue and placenta.

Woman after miscarriage

What should I do if I’m worried I am miscarrying?

Contact your GP. He/she will examine you to see if the neck of your womb is opening. If they’re concerned they’ll send you to hospital where you may be given an ultrasound (sometimes performed using a small probe inside the vagina which will not increase your risk of miscarriage if your pregnancy is actually safe) to check the baby’s heartbeat and development. You may also be given a blood test to measure the hormone levels associated with pregnancy. 

If you are miscarrying then sadly there’s nothing that can be done to stop it but it’s reassuring to know that should you decide to try again you have exactly the same chance of having a normal pregnancy as before.

Is there anything I can do to prevent miscarriage?

‘We know that being overweight makes it harder to push sugar out of your bloodstream and this seems to affect the development of the baby so if you’re considering pregnancy it might be worth losing a few pounds,’ Diana says.

‘We also know that smoking and drinking isn’t a good idea.’

Eat a healthy diet with plenty of fruit and vegetables and carry on exercising in moderation, she says. While it’s unwise to go from nothing to a marathon overnight there’s evidence to suggest gentle exercise – walking and swimming for example – is healthy during pregnancy.  

The blood test that predicts the chances of miscarriage

In a study of nearly 2,000 pregnant women who had been through IVF, scientists from the Glasgow Centre for Reproductive Medicine found low levels of the hormone beta-human chorionic gonadotrophin soon after conception were linked to an increased risk of miscarriage. 

With this in mind, a simple blood test could be used to tell women the likelihood of a pregnancy ending in miscarriage. 

Beta-human chorionic gonadotrophin is made when cells form in the placenta, to nourish the egg and help it attach to the wall of the uterus during implantation. During pregnancy, levels of the hormone are expected to rise steadily, especially during the first trimester.

In the study, when the hormone levels were below 30 units per litre, the success rate of pregnancy was only 2%. If women had between 50 to 70 litres of the hormone, pregnancy success rose to 52%. Finally, if women had more than 70 litres, they had an 86% chance of having a healthy pregnancy.

These findings mean that IVF patients and clinicians could have more than just a positive pregnancy test to predict the outcome of their treatment.

Marco Gaudoin, from GCRM said: ‘The level gives us a clear guide, helping us to counsel patients about the likelihood of a miscarriage, which in turn will help us to better prepare patients psychologically and emotionally.’

Pregnancy blood test

According to the NHS your blood can also be checked for high levels of the antiphospholipid (aPL) antibody and lupus anticoagulant. This test should be done twice, a few weeks apart, when you're not pregnant.

These aPL antibodies are known to increase the chance of blood clots and change the way the placenta attaches. These blood clots and changes can reduce the blood supply to the foetus, which can cause a miscarriage.

After a miscarriage, it’s understandable that you want to know why it happened and what might be done to stop it happening again.

However, if this is your first or second miscarriage – or if you have had a mix of miscarriages and healthy pregnancies – you probably won’t be offered tests or treatment.

This can be frustrating and upsetting. You might feel that no-one is taking your losses seriously. However, as most miscarriages are due to chance rather than underlying causes for concern, most women who have one or two miscarriages will go on to have a successful pregnancy next time. 

If you’ve had three miscarriages or more in a row (the definition of recurrent miscarriage), you should be offered tests. That’s because a cause is more likely to be found at this stage. You may also be offered tests after a second trimester loss or after two miscarriages if it has taken you a long time to conceive.

Who can I talk to if I’m still worried?

Whoever you reach out to, the most important thing is to reach out to someone. Whether that be your partner, a friend, family. While it is a devastating thing to experience, sharing these experiences is vital to understanding that you're not alone. There are numerous phonelines, websites and people who will listen and understand what you're going through. Above all, do not lose hope.

‘Remember there’s an 85% chance you won’t suffer a miscarriage and bear in mind even a woman who has had three miscarriages still stands a 65% chance of her next pregnancy being successful,’ Diana says.

Need to talk to someone? Here’s how to get help when you need it


I lost a baby on Christmas Eve. A life so small and unexpected and yet from the very moment I’d learnt of its existence, the most significant thing in the world to me. No matter what anyone says, you plan out an entire lifetime in those first few months. It was a ‘missed miscarriage’ - only identifiable at a scan punctuated by pained silence rather than joy and ‘managed’ by surgery a week later. Thank you for your patience and kindness whilst I’ve taken time offline over the last 3 weeks. They have been the hardest of my life. I decided to take some space whilst my body healed and I began learning how to navigate this new territory of grief, loss and all the hurt and confusion that accompanies it. I knew the stats, I just didn’t think I’d become one of them. It’s a membership without a cancellation clause to a club that nobody wants to be a part of. So for now I’m taking life a day at a time, buoyed by the immense strength and bravery I’ve witnessed in others. ❤️ #1in4

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Having worked across a variety of magazines, on topics from food to travel to horses, Stephanie now works as a Digital Writer for Mother&Baby online. 

She loves taking her lurcher puppy Moss for long walks in the country, and spending time with her niece and two nephews. In her spare time she writes fiction books and enjoys baking (her signature bake is lemon drizzle cake).

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