10 Things to Know About Miscarriages

Here’s the truth about what does and doesn’t cause pregnancy loss, and what happens next.

Updated on March 19, 2024

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Miscarriage is not often talked about or discussed openly. But it is much more common than you may realize. For many people, it can be a difficult experience, both physically and emotionally. Althea O’Shaughnessy, MD, a fertility specialist with Conceptions Reproductive Associates of Colorado, explains common causes of miscarriage, and what you can do to help support a healthy pregnancy.

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Miscarriage rates are high

An estimated 26 percent of all pregnancies end in miscarriage, and 80 percent of early pregnancy losses happen during the first trimester. The risk of miscarriage declines after the first 12 weeks of pregnancy. This does not take into account miscarriages that occur before someone knows that they are pregnant. So, miscarriages may be even more common.

“I’m sure if you talk to five women, one out of those five are going to have had a miscarriage at one point in their lives, or they’ll know someone who did,” says Dr. O’Shaughnessy.

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They’re most often caused by a chromosomal issue

Most miscarriages occur because the pregnancy is not viable. This mean that the pregnancy will never result in the birth of a live born baby. This is most often due to problems with chromosomes—the thread-like strands inside cells that contain DNA or genes. Around 60 percent of pregnancy losses occur because the embryo—the fertilized egg that has divided into cells and implanted itself into the wall of the uterus—receives an incorrect number of chromosomes, according to ACOG.

Typically, the sperm has 23 chromosomes and the egg has 23. But if there is an abnormal number, issues can occur in a developing embryo. When a chromosome abnormality is so damaging that further development is not possible, the embryo or fetus is expelled or forced out of the uterus.

Though people who have experienced a miscarriage may wonder if they could have done anything to prevent it, the answer is usually no. Working a lot, exercising, having sex, and using birth control in the years before becoming pregnant do not cause miscarriage, ACOG says. It’s also unlikely that stress contributes to the chance of miscarriage. Falls are generally not a concern early in pregnancy, but they do become a concern after 14 weeks. This is because later in pregnancy when the fetus grows larger, the uterus is no longer protected by the pelvis. Speak with a healthcare provider (HCP) about the lifestyle habits you can establish to increase your chances of having a healthy pregnancy.

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Certain health conditions or medications may increase your risk

Some chronic health conditions can make it more difficult to sustain a pregnancy. Many of these involve the condition of your uterus, while others affect your general health. Some of these issues include:

  • Problems with the uterus, such as a uterus that is separated into two sections with a wall of tissue in the middle (septate uterus)
  • Fibroids and polyps, benign growths within the uterus that distort the uterine cavity  
  • Asherman syndrome, a condition that involves scar tissue inside the uterine cavity
  • Thyroid gland conditions such as low thyroid and high thyroid
  • Blood clotting issues such as antiphospholipid antibody syndrome, a condition in which the immune system attacks normal proteins in your blood which increases the chance for blood clots
  • Polycystic ovary syndrome, a condition caused by an imbalance of reproductive hormones
  • Diabetes, especially in people whose blood sugar is not well-controlled

If you experience a miscarriage, or are thinking of becoming pregnant, check in with your HCP to identify and treat any potential health issues. Blood tests can often detect clotting issues, genetic causes, and thyroid conditions. And routine infertility screening tests like hysterosalpingography (a special X-ray of the uterus and fallopian tubes) or an ultrasound can show an image of your reproductive organs to help identify anything of concern. But sometimes there is no clear answer: in 50 percent of cases there is no identifiable cause for repeated miscarriages.

Treatments often depend upon the type and severity of the issue, miscarriage history, and your plans for becoming pregnant. Certain medications, including some antibiotics and antifungal medications, have been associated with a higher rate of miscarriage. If you’re taking any medications or need a new prescription while you are pregnant, be sure to talk with your HCP about how this may affect your pregnancy.

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Age may contribute to risk

Just as the risk for fertility issues increases as you get older, your risk of miscarriage also rises. And although abnormal sperm issues might contribute, too, in most cases, the concern is the quality of the egg, says O’Shaughnessy.

One-third of people who get pregnant after 40 experience early pregnancy loss. “While you age, your eggs are sitting around in a suspended state,” says O’Shaughnessy. “This can affect the way in which chromosomes separate and can cause chromosomal abnormalities in the eggs themselves, otherwise known as ‘an error in meiosis.’”

As a fertility specialist, O’Shaughnessy performs assisted reproductive procedures such as in vitro fertilization (IVF), in which she retrieves eggs from the patient’s ovaries; the eggs are then fertilized by sperm in a lab and then transferred back to the uterus. She has found that for people in their 20s, up to 20 percent of their eggs may test as abnormal. For people over 40, however, as many as 80 percent may be abnormal.

If you are 35 or older, especially if you’ve been trying to get pregnant for more than six months or you’ve had multiple miscarriages, talk with an HCP about having an evaluation. Blood tests can help identify any conditions that may predispose you to miscarriage. Your HCP can answer questions about whether or not you should keep trying to get pregnant naturally, and if so, for how long. Depending on your circumstances, you may want to discuss fertility treatment options.

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It’s best to give up smoking and alcohol

Quitting cigarettes, vapes and alcohol while you’re pregnant or trying to conceive can help you have a healthier pregnancy, and may lower your risk for miscarriage. Though the research is not completely clear, there is some evidence that smoking can increase the risk of miscarriage. Alcohol use during the first trimester may also slightly increase the risk of early pregnancy loss, says O’Shaughnessy.

“Smoking affects blood flow to the ovaries,” O’Shaughnessy says. “When we do IVF on people who smoke, we find that the quality of their eggs and their embryos are definitely impacted.”

Experts do not recommend consuming any amount of alcohol during pregnancy or while trying to conceive. Drinking can cause fetal alcohol spectrum disorders, which are associated with a variety of health problems for the baby, including learning differences, vision and hearing problems, and low body weight. Drinking during pregnancy can also increase the risk of miscarriage.

Other substances, including marijuana, cocaine, heroin, and methamphetamine can increase the risk of poor pregnancy outcomes, including miscarriage. These drugs pass to the fetus through the placenta (the organ that develops inside the uterus to support and nourish a fetus), and the exposure to these drugs can not only lead to miscarriage, but also birth differences, infant withdrawal symptoms, and placental abruption, when the placenta separates from the uterine lining.

Talk with your HCP before becoming pregnant if drug or alcohol use is an issue. You can also reach out to the following resources for help:

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It's important to maintain a healthy weight...

People who are severely underweight or overweight have a more difficult time sustaining a pregnancy. A 2016 study published in The Lancet Diabetes & Endocrinology found that women whose body weight puts them in the range of obesity are more likely to have a miscarriage than women who are not obese. They are also more likely to deliver prematurely (birth before the 37th week of pregnancy) and have newborns with certain health conditions. People with obesity are also more likely to have recurrent miscarriages. Miscarriage risk is higher in those with obesity who are undergoing assisted reproductive therapy like IVF, as well. Obesity can cause hormone fluctuations, which can interrupt embryonic development. If you are concerned about your weight, talk to your HCP or a registered dietitian about finding an eating and exercise plan that will help you take off pounds in a healthy way.

For those who are underweight, taking supplements and eating more fresh fruits and vegetables may reduce the risk of miscarriage, according to one British study (always talk to your HCP before taking any supplements). If you have disordered eating, contact the National Eating Disorder Association's Live Helpline at 800-931-2237 to find help.

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High blood pressure may play a role

Those with high blood pressure may also have an increased risk of miscarriage. One 2018 study published in the journal Hypertension observed 1,228 mostly overweight or obese women who had had at least one miscarriage and were trying to get pregnant again. Risk of pregnancy loss was found to increase with increased blood pressure. This suggests that high blood pressure is associated with miscarriage.

Whether obesity, high blood pressure, or both are factors in your life, experts recommend managing your blood pressure and weight. The American Heart Association recommends getting regular exercise and following the Dietary Approaches to Stop Hypertension (DASH) or Mediterranean-style diets. These eating plans focus on fruits, vegetables, low-fat dairy, whole grains, lean protein like fish and poultry, healthy fats like nuts and vegetable oils, as well as lower amounts of added sugars, salt, red meat, and saturated fat (which is solid at room temperature, like butter).

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You may need a procedure to help clear the uterus

If you miscarry early in your pregnancy, you may experience cramps, pain, and bleeding—or you may not have any symptoms at all and only discover the pregnancy has ended during an ultrasound. If you find yourself bleeding and cramping, contact your HCP right away. If you are miscarrying and there are no signs of infection, you’ll likely have the choice to wait and allow the tissue to pass naturally. You may pass a miscarriage naturally or with medication prescribed by your HCP that can help your body pass the tissue and placenta more quickly. The process does not require surgery, but you should be prepared for pain and bleeding that can last up to two weeks in some cases.

If there is a complication, such as a septic miscarriage (an incomplete miscarriage where some tissue is not cleared from the uterus, resulting in an infection), your HCP may recommend a dilation and curettage (D&C), a surgical procedure to remove that tissue. It’s likely you’ll receive anesthesia for the surgery, which numbs your body and relieves pain.

Your HCP can provide you with information about the risks and benefits so that you can reach a decision that’s right for your situation. If there is an incomplete miscarriage without infection, heavy bleeding or other problems, you may have a choice of options.

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It can help to take time to process the experience

Once your HCP has confirmed you’re having a miscarriage, take some time to process the news, suggests O’Shaughnessy. Emotions about pregnancy loss can vary from person to person, and there is no “correct” way to feel about it. However you are feeling, this is a good time to reach out for support from others. You can meet with your HCP on a different day to make a decision about how you’d like to proceed.

Whether your pregnancy lasted 5 weeks, 12 weeks, or longer, the period of time after a miscarriage, whether you let the tissue pass naturally or through surgery, may be difficult. You may have trouble sleeping, working and eating, and you may experience a range of emotions, from happiness or relief to sadness, anger, or grief.

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It’s okay to reach out for help

“There’s no right or wrong way to handle a miscarriage,” says O’Shaughnessy. But talking with someone who’s been through what you’ve experienced—whether it’s someone you know or someone you meet through a support group—can provide comfort. Sharing stories may enable you to understand what’s happened, and eventually, how to move on.

Resources like UnspokenGrief and M.E.N.D can connect you with others who’ve experienced miscarriage and provide you with stories about fertility after pregnancy loss. The March of Dimes can also send you a bereavement kit with additional resources if they may be helpful to you.

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Planned Parenthood. How do I know if I'm having a miscarriage? Accessed April 20, 2023.
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Boutari C, Pappas PD, Mintziori G, et al. The effect of underweight on female and male reproduction. Metabolism. 2020 Jun;107:154229.
The American College of Obstetricians and Gynecologists. Early Pregnancy Loss: Frequently Asked Questions. Page last updated January 2022.
The American College of Obstetricians and Gynecologists. Repeated Miscarriages: Frequently Asked Questions. Page last reviewed November 2020.
Mølgaard-Nielsen D, Svanström H, Melbye M, Hviid A, Pasternak B. Association Between Use of Oral Fluconazole During Pregnancy and Risk of Spontaneous Abortion and Stillbirth. JAMA. 2016;315(1):58-67.
Hahn KA, Hatch EE, Rothman KJ, Mikkelsen EM, Brogly SB, Sørensen HT, Riis AH, Wise LA. History of oral contraceptive use and risk of spontaneous abortion. Ann Epidemiol. 2015 Dec;25(12):936-41.e1.
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Sundermann AC, Velez Edwards DR, Slaughter JC, et al. Week-by-week alcohol consumption in early pregnancy and spontaneous abortion risk: a prospective cohort study. Am J Obstet Gynecol. 2021;224(1):97.e1-97.e16.
National Institute on Drug Abuse. Substance Use in Women Research Report: Substance Use While Pregnant and Breastfeeding. April 2020.
Cavalcante MB, Sarno M, Peixoto AB, Araujo Júnior E, Barini R. Obesity and recurrent miscarriage: A systematic review and meta-analysis. J Obstet Gynaecol Res. 2019;45(1):30-38.
Poston L, Caleyachetty R, Cnattingius S, et al. Preconceptional and maternal obesity: epidemiology and health consequences. Lancet Diabetes Endocrinol. 2016;4(12):1025-1036.
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Malasevskaia I, Sultana S, Hassan A, Hafez AA, Onal F, Ilgun H, Heindl SE. A 21st Century Epidemy-Obesity: And Its Impact on Pregnancy Loss. Cureus. 2021 Jan 1;13(1):e12417.
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