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Risks associated with miscarriage

Feb 14, 2022 | 2 minutes Read

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, went snowboarding, 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 fetuses are resilient and not bothered by bumps, bangs, bad food or a mother's dark state of mind.

Miscarriage risk statistics

Miscarriage is more common than many people think, with many women having at least one miscarriage. Many women miscarry more than once. 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 fertilized egg even implants in the womb.

Early after implantation, and before a pregnancy is clinically recognized, around 26% will miscarry. After a pregnancy can be clinically recognized, which is between days 35 50, around 10% 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:

Chances of recurrent miscarriage
  • First pregnancy 5%
  • pregnancy terminated 6%
  • 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, there are other factors that may increase miscarriage danger. Some of these danger factors, such as smoking, can be avoided. Other 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 toto 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.

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 stillbirth.

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 yet, it would be wise to be on the safe side and switch to herbal teas.

Age is a factor. Older women are more likely to miscarry 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%.

Certain infections carry a somewhat higher risk to your baby. They include Listeria, mumps, rubella, measles, HIV and gonorrhea. Your prenatal care should include tests for infections. If risky infections are detected, your provider 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 labor.

Exposure to toxins such as lead, arsenic, some chemicals, and large doses of radiation or anesthetic gases might increase your danger of miscarriage.

Drinking any amount of alcohol in early pregnancy increases the risk of miscarriage by 19%, according to 50 years of research. Alcohol certainly damages unborn babies. There is no known safe amount of alcohol in pregnancy, nor time in pregnancy when the fetus is not affected.

The father’s health and age may contribute to miscarriage risk. The 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 testing and chorionic villus testing (CVS) for chromosomal disorders also tend to slightly increase the chances of miscarriage. Amniocentesis carries a 0.5 to 1% miscarriage risk within 3 weeks of the test. CVS carries a 1.2% 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 chromosomally faulty fetus, 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, including small children. Pregnant women have always carried an older child on their hip. It's thought you can safely lift up to 18 to 20 pounds without any danger. And you are likely to automatically drop a heavy item before any harm could occur.
  • Bad eating habits. a shortage of folic acid can cause neural tube defects such as spina bifida, sometimes forgetting to take your vitamins or chowing down on a fast food burger won’t 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. Your baby is cushioned by amniotic fluid so they are unlikely to be hurt, especially in the first trimester. However, you should always see a doctor if you have any type of jarring injury or are hurt, especially in the second or third trimester, as trauma could cause the placenta to detach and potentially lead to late pregnancy loss. If the blow is from domestic violence, seek immediate help and protection.
  • Sex. 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. Drink plenty of water, wear loose-fitting clothing, and exercise in a temperature-controlled room or outside unless it’s very hot or humid. Avoid becoming overheated, especially in the first trimester. It's thought that if you don’t overdo intensely physical activities, 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. 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. 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. These 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 a warm bath increases the chances of miscarriage. However, some doctors advise pregnant women to steer clear of saunas and hot tubs, just to be on the safe side.

The information of this article has been reviewed by nursing experts of the Association of Women’s Health, Obstetric, & Neonatal Nurses (AWHONN). The content should not substitute medical advice from your personal healthcare provider. Please consult your healthcare provider for recommendations/diagnosis or treatment. For more advice from AWHONN nurses, visit Healthy Mom&Baby at health4mom.org.