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Why might miscarriages happen: Common causes

Pregnancy loss is one of the most difficult things a family can go through, but it’s important to know that you aren’t alone, as it’s believed that 10-20%, and maybe up to 25%, of known pregnancies end in loss. Most women who experience pregnancy loss will go on to conceive again and deliver healthy babies.

What are some common causes of miscarriage?

Although pregnancy loss is common, there are a number of different factors that may lead to or contribute to pregnancy loss. Some of the more common reasons for miscarriage are described below.

Chromosomal abnormalities

Genetic factors cause a wide array of chromosomal abnormalities, which in turn can cause miscarriage. It’s hard to prevent these situations, but informing your healthcare provider of your full family history and performing specific blood work to test for these conditions can sometimes help women determine if genetic factors will be a risk factor.

Uterine abnormalities

Uterine abnormalities can prevent pregnancy from occurring, or increase the risk of miscarriage if conception does occur. A woman’s uterus can be shaped in such a way that makes conception difficult, divided by a misplaced muscle, or not fully formed. These problems are often congenital, or present from birth, but have gone unnoticed until a woman is trying to conceive. Fibroids, scarring, and a retroverted or tipped uterus are also conditions that can cause miscarriage.

Cervical insufficiency

This occurs when the cervix begins to dilate and thin too early in pregnancy. This can lead to miscarriage, especially after the first trimester. It can be hard to diagnose an insufficient cervix before symptoms start to occur, but once diagnosed, providers may be able to treat the problem early and will carefully monitor the woman throughout the rest of her pregnancy. However, if treatment is unsuccessful and the cervix continues to dilate, early induction and delivery might be unavoidable.

Untreated illnesses and bacterial infections

Minor infections such as yeast infections or the common cold should not impact the health of your fetus. Rather, women need to be aware of some of the more serious illnesses that could impact their pregnancy and ensure they are treated before pregnancy, or as soon as possible after learning they are pregnant. Some of these include syphilis, bacterial vaginosis, malaria, toxoplasmosis, influenza, a prolonged fever, epilepsy, or thyroid disease. Healthcare providers test women for some of these diseases during the initial obstetric appointment – this includes chlamydia, gonorrhea, HIV, and Hepatitis B, but if you know you are at an increased risk for any disease, you should inform your provider.

Polycystic Ovary Syndrome (PCOS)

Women with PCOS are nearly three times more likely to experience miscarriage than women who don’t have the condition. Treatment is especially important in these cases, because certain medications such as metformin might reduce this risk of miscarriage.

Lifestyle factors

Certain lifestyle factors, such as the use of alcohol, drugs, or tobacco, high levels of stress, obesity, and excessive amounts of caffeine can contribute to the likelihood of pregnancy loss.

Immunologic disorders

Immunologic disorders are disorders in which the body’s immune cells attack healthy cells within your body. A large number of these disorders exist and vary greatly in cause, and certain types can impact the health of your pregnancy. One example is antiphospholipid syndrome (APS), an autoimmune disorder that affects blood clotting and raises the risk of miscarriage. Lupus and type 1 diabetes are other examples of illnesses that can cause miscarriage. Blood tests can help diagnose an autoimmune disorder, and from there, treatment and intervention vary by the individual, and her healthcare provider.


Sources
  • “Common Causes of Miscarriage.” RESOLVE. RESOLVE: The National Infertility Association, 2016. Web.
  • “Uterine and ovarian abnormalities.” MarchofDimes. March of Dimes Foundation, Aug 2015. Web.
  • Lucia Halmen. “Does Incompetent Cervix Cause Miscarriage During The First Trimester?” PregnancyTips. Conceive Media Network, Jul 22 2015. Web.
  • “Repeated Miscarriages FAQ.” ACOG. American College of Obstetricians and Gynecologists, May 2016. Web.
  • “Does PCOS affect pregnancy?” NIH. US Department of Health and Human Services, May 23 2013. Web.
  • Sevi Giakoumelou, Nick Wheelhouse, Kate Cuschieri, Gary Entrican, Sarah E.M. Howie, and Andrew W. Horne. “The role of infection in miscarriage.” OxfordJournals. Human Reproduction Update from the European Society of Human Reproduction and Embryology, Sep 19 2015. Web.

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