Chances of Miscarriage

With any pregnancy there is always miscarriage risk, regardless of how well the woman takes care of herself. When pregnancies miscarry it's almost always because the embryo is defective; not because the mother went clubbing, had sex, didn t sleep, drank alcohol, went mountaineering, ate a dodgy prawn, or had ambivalent feelings about motherhood. If these things increased the chances of miscarriage, then the world's population would be much smaller! The fact that babies get born in war zones to women suffering enormous stress and poor nutrition proves that healthy foetuses are pretty resilient and not bothered by bumps, bangs, bad food or mother's dark state of mind.

Miscarriage risk statistics

It is more common than many people think, with a large number of women having at least one miscarriage. Many women miscarry more than once. Considering the frequency of it, about 1 in 36 women will have 2 miscarriages due to nothing more than chance.

The chance of it happening decreases as pregnancy progresses. It is thought that as many as half of all pregnancies miscarry before the fertilised egg even implants in the womb. Early after implantation, and before a pregnancy is clinically recognised, around 30% will miscarry. After a pregnancy can be clinically recognised, which is between days 35 50, around a quarter of pregnancies will end in miscarriage. However, chance of it happening, decreases dramatically after week 8.

Many people wonder if their chances of losing a baby goes up if they've already lost a pregnancy. There are many opinions about this, but a Recurrent Miscarriage clinic in London did a study that found miscarriage danger does relate to pregnancy history:

  • First pregnancy 5%
  • Last pregnancy terminated 6%
  • Last pregnancy a live birth 5%
  • All pregnancies live births 4%
  • 1 previous miscarriage 20%
  • 2 previous miscarriages 28%
  • 3 previous miscarriages 43%

Miscarriage risk factors

Aside from nature taking its course and miscarrying a defective foetus, there are other factors that may increase miscarriage danger. Some of these danger factors, such as smoking, can be avoided. Others factors such as diabetes can be controlled and managed to help reduce the danger to pregnancy.

  • Smoking is believed to increase the chances of not carrying your baby to term by 30 50%. So if you're planning to conceive or are pregnant already, you and your partner now have the perfect incentive quit. Moreover, if you were worried you d put on weight if you gave up smoking, now it won t matter so much. Also, as well as reducing your chances of miscarriage, your lung capacity and efficiency will improve which will become increasingly important as your growing womb pushes up against your lungs. Smoking during pregnancy also exposes your unborn baby to dangerous chemicals like nicotine, carbon monoxide and tar. They can reduce the amount of oxygen your baby gets through the placenta, causing low birth weight, damage to the baby's lungs, and even still-birth.
  • Coffee is thought to increase the danger of miscarriage if you drink more than four cups a day. Although there isn t conclusive scientific proof as yet, it would be wise to be on the safe side and switch to herbal teas or hot chocolate.
  • Age is a factor. Teenagers are more likely to miscarry, as are older women because there's a greater chance of chromosomal defects.
  • Some chronic diseases or disorders, including poorly controlled diabetes, certain inherited bloody clotting disorder, certain autoimmune disorders such as Lupus, and certain hormonal disorders such as polycystic ovary syndrome can increase the odds of miscarriage. But on a positive note, many of these conditions can be treated or at least managed. For example, if you have a blood-clotting disorder, anticlotting medication may cut your chances of miscarriage by as much as 75%. Usually pre pregnancy doctors with do full blood works to envisage immunity to certain infections and viruses.
  • Certain infections carry a somewhat higher menace to your baby. They include listeria, mumps, rubella, measles, HIV and gonorrhoea. Your antenatal care should include tests for infections. If dangerous infections are detected, your doctor or obstetrician will recommend a course of treatment.
  • Abnormalities of the uterus or cervix increase your danger, including a weak or short cervix. Some abnormalities are fixable. For example, if a weak cervix has caused a previous miscarriage, a stitch applied at the end of the first trimester in your next pregnancy can stop your cervix from opening early and starting premature labour.
  • Exposure to toxins might increase your danger, including lead, arsenic, some chemicals, and large doses of radiation or anaesthetic gases
  • Alcohol consumption is thought by some but not all doctors to increase the chances of miscarriage. Alcohol certainly damages unborn babies so it's best to give it a miss while you are pregnant and breastfeeding.
  • Father's health and age may contribute to miscarriage risk. Father's age is now believed to be almost as significant as the mother s, with miscarriage risk increasing with father's age. Some studies have found that the danger of miscarriage also increases if the father has been exposed to mercury, lead and some industrial chemicals and pesticides.
  • Hormone imbalance, such as low progesterone during pregnancy can keep the uterus from nourishing the embryo. This can be diagnosed and treated.
  • Amniocentesis and CSV tests for chromosomal disorders also tend to slightly increase the chances of miscarriage. Amniocentesis carries a 0.5 to 1 percent miscarriage risk within 3 weeks of the test. CVS (chorionic villus sampling) carries a 1 2 per cent risk of causing miscarriage.

Miscarriage risk myths and claims

There are lots of myths and bogus claims about miscarriage risk, many of which were used to explain the mysteries of pregnancy before science came up with the truth.

From the dark age's right up to the present day, women have been made to feel guilt, shame and blame for miscarriages. Even though we now know that miscarriage is usually nature stopping the development of a faulty foetus, or due to an often fixable anatomical problem or health condition, women still ask their doctors, What did I do wrong?

Here are some common myths and claims explained or debunked:

  • Stress or working too hard. Many women are stressed when they're pregnant yet go on to have healthy babies. However, recent research suggests stress may be a factor for women who have had multiple miscarriages.
  • Lifting heavy things such as small children. Pregnant women have always carried an older child on their hip. It's thought you can safely lift up to 8 or 9 kg without any danger. And you are likely to automatically drop a heavy item before any harm could occur.
  • Drinking alcohol. A foetus receives so little of its mother's blood for the first few weeks of pregnancy that alcohol consumption is not considered a danger in the early stages. Yet women continue to torture themselves over those glasses of wine or tequila shots they enjoyed before they knew they were pregnant. But continuing to drink when you know you're pregnant is asking for trouble as alcohol can cause Foetal Alcohol Syndrome.
  • Bad eating habits. Although a shortage of folic acid can cause neural tube defects such as spina bifida, forgetting to take your vitamins or chowing down on a fast food burger won t generally harm your baby but it will affect you. The baby will take what it needs from your body and you will feel any shortfalls in vitamins and minerals.
  • Falling over or a blow to the stomach. Baby is cushioned by amniotic fluid so is unlikely to be hurt, especially in the first trimester. However, you should always see a doctor if you are hurt, especially in the second or third trimester as a trauma could cause the placenta to detach and potentially lead to late pregnancy loss. If the blow is domestic abuse, seek immediate help and protection.
  • Sex does not hurt an unborn baby, although it can be uncomfortable for you in some positions. Don t be alarmed if there is some blood spotting afterwards. This spotting occurs because the cervix is very soft and its blood vessels are prominent and close to the surface during pregnancy. Unless your doctor advises otherwise (which may be the case if you've had recurrent miscarriages or have a condition called placenta previa), there's no need to move into the spare room.
  • Exercise. Keeping up your fitness or starting a gentle exercise regimen has big benefits for your health and your baby's during pregnancy. It's thought that as long as you don t raise your heart rate above 140bpm or overdo intensely physical activities such as martial arts, exercise is not generally a miscarriage risk.
  • Bad moods or negative feelings about the baby. No matter how dark your thoughts, there's no way your baby can read them or react to them!
  • Previous elective abortions. Evidence is mixed on this one. Some studies claim a slight increased risk, while other research identifies no increased chances of miscarriage.
  • Birth control pills can cause miscarriage. There is no evidence that taking the pill will cause a miscarriage in an established pregnancy or that taking the pill will increase your future miscarriage risk.
  • Aspirin increases miscarriage risk. There is some evidence that non-steroidal anti-inflammatory drugs can increase the danger but the evidence is mixed. Moreover, low doses of aspirin are sometimes prescribed as part of recurrent miscarriage treatment.
  • Hot baths or saunas could cause your body temperature to get too high and possibly cause developmental problems but there is no convincing evidence that a long soak in the tub increases the chances of miscarriage. However, some doctors advise pregnant women to steer clear of saunas, just to be on the safe side.


For more information and support, see your General Practitioner, midwife or health care professional. You can also visit or, or call the SANDS helpline on 1300 072 637.

16/09/21 - min Read

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