A miscarriage cannot be prevented in most cases. A miscarriage is a pregnancy that ends unexpectedly in the early weeks or months. This is also called a spontaneous abortion.

The factors that lead to most miscarriages are unavoidable. These issues include chromosomal abnormalities and fetus development problems.

Miscarriages are not uncommon. About 10 percent of early pregnancies end in a miscarriage before the twentieth week. The real number of miscarriages may actually be higher, too, as many people miscarry before knowing they’re pregnant.

While you cannot prevent a miscarriage, you can take steps to have a healthier pregnancy. This may lower the risk of a miscarriage by reducing the risk of possible causes of the premature end of the pregnancy.

Pinpointing an exact cause for a miscarriage is difficult. In most cases, the cause is something you couldn’t have prevented, meaning you couldn’t have prevented the miscarriage, either.

Rarely, doctors are able to find an issue that increases the risk for a miscarriage. In that case, treating the issue may help prevent a future miscarriage.

First trimester

Around 80 percent of miscarriages occur in the first trimester. The first trimester refers to the time between weeks 1 and 13.

Common causes of miscarriage in the first trimester include:

  • Genetic abnormalities. More than half of all first trimester miscarriages are the result of problems with the fetus’s chromosomes. If your body detects the fetus has damage or missing chromosomes, it will end the pregnancy.
  • Blood clots. A condition called antiphospholipid syndrome (APS) causes blood clots that can end a pregnancy. This condition can be treated with medications to prevent a miscarriage.
  • Ectopic pregnancy. This potentially serious but rare type of pregnancy occurs when the fetus begins developing outside the womb. Ectopic pregnancies cannot be saved and are a medical emergency requiring immediate treatment.
  • Placental problems. If the fetus and placenta are not compatible, the pregnancy may be lost. Likewise, uterine defects, including an abnormal shape, may also cause the sudden end of a pregnancy.

Second trimester

A miscarriage in this later stage of pregnancy, weeks 13 to 24, is much less common. If it does occur, the cause is likely related to external health conditions, or problems with the mother’s health.

These second trimester issues that may lead to pregnancy loss include:

  • Infection. Infections within the uterus or cervix can lead to a miscarriage. Likewise, food-borne illnesses may put a woman at risk for a miscarriage.
  • Chronic conditions. Chronic conditions like diabetes or high blood pressure increase a woman’s risk of having a miscarriage. The risk is higher if the condition isn’t properly treated or managed.
  • Thyroid disease. Untreated thyroid conditions increase risk of miscarriage.
  • Autoimmune conditions. Lupus, as well as other autoimmune conditions, can lead to a miscarriage.
  • Problems with the uterus or cervix. Fibroids or an abnormally shaped womb may cause a miscarriage.
  • Lifestyle factors. Smoking, second-hand smoke, consuming alcohol, and drug use can interfere with a fetus’s development. High caffeine consumption may also be problematic.
  • Environmental factors. Exposure to certain chemicals or hazards can cause a miscarriage. These include mercury, solvents, paint thinners, pesticides, and heavy metals.

Third trimester

At this late stage of a pregnancy, a miscarriage is more commonly called stillbirth. The same issues that can cause a miscarriage in the first two trimesters of a pregnancy can also be responsible for a pregnancy loss in the third trimester. But, understanding the exact cause is often difficult.

These issues may include:

  • Pregnancy complications. This includes preterm labor or the separation of the placenta from the womb.
  • Birth defects. One in 10 stillbirths are the result of a genetic or structural birth defect.
  • High blood pressure. Preeclampsia occurs in 5 to 8 percent of all pregnancies. While the greatest risks of this condition are to the mother, preeclampsia can cut off the supply of oxygen and nutrients to the fetus. Preeclampsia can also progress to eclampsia, a very serious condition that can be fatal to the fetus and woman.
  • Uncontrolled diabetes.
  • Infection. An infection in the placenta or in the fetus can cause the end of the pregnancy.
  • Problems with the umbilical cord. If this cord is knotted or squeezed, it can cut off the flow of blood and oxygen to the fetus.
  • Problems with the placenta. Insufficient blood flow to the placenta can end in a miscarriage.

Miscarriage cannot be prevented in most cases. However, you can improve your chances of a healthy pregnancy and possibly reduce your risk for miscarriage with these tips.

Take folic acid

Research that taking 400 micrograms (mcg) of folic acid daily might reduce the risk of birth defects that can lead to miscarriage.

Start taking this B vitamin every day before you intend to get pregnant. Continue taking it during pregnancy for the greatest benefits.

Follow a healthy lifestyle

Avoid unhealthy risk factors, such as:

  • smoking
  • second-hand smoke
  • alcohol consumption
  • drug use

You should also limit your caffeine intake to 300 milligrams (mg) or less per day.

In addition to avoiding risks, you may also be able to improve your pregnancy health by:

  • getting regular exercise
  • getting adequate sleep
  • eating a healthy, well-balanced diet during all three trimesters

Maintain a healthy weight

Being overweight, obese, or underweight may increase your risk for complications during pregnancies. This includes miscarriage.

Take precautions against infections

Wash your hands frequently. This can help you avoid illnesses like the flu and pneumonia, which are easily spread.

Make sure your immunizations are all up to date, too. Talk with your doctor about any other immunizations you might need during pregnancy, including the flu shot.

Manage chronic conditions

If you have a health issue, such as high blood pressure, diabetes, or an autoimmune disease, work with your doctor to properly treat or manage it. This can help prevent miscarriages when you become pregnant.

Practice safe sex

Some sexually transmitted diseases (STDs) can lead to complications during pregnancy. Get tested before you try to get pregnant. If you’re already pregnant, get tested as soon as possible.

During pregnancy, use barrier methods properly in every sexual encounter, including oral or anal sex, to reduce your risk for STD.

The most common signs of a miscarriage include:

  • spotting that lasts longer than three days
  • bleeding that may include clots or tissue
  • mild to severe pain and cramping in your back and abdomen
  • weight loss
  • fluid or mucus discharge from the vagina
  • a decrease in signs of pregnancy, such as breast tenderness, nausea, and vomiting

If you think you’re experiencing signs of a miscarriage, seek emergency treatment. Your doctor can perform a physical exam to determine the cause of the symptoms.

In most cases, you cannot stop a miscarriage once it has started, no matter the trimester you are currently in. The symptoms of a miscarriage typically indicate the pregnancy is already over.

In some cases, the symptoms may be a sign of a condition called threatened miscarriage. This can occurs in people who are less than 20 weeks pregnant. You may experience heavy bleeding and assume your pregnancy is ending.

However, if a fetal heartbeat is still present, the pregnancy can continue, despite what appears to be signs of an impending miscarriage. It’s important, however, that you work with your doctor to help prevent a full miscarriage.

Treatment for a threatened miscarriage includes:

  • bed rest
  • avoiding sexual intercourse
  • treatment for any underlying conditions that may be causing the bleeding
  • an injection of the hormone progesterone
  • an injection of Rh immunoglobulin if your baby has Rh-positive blood and you have Rh-negative blood

There is no shortage of misunderstandings and myths about the unexpected end of a pregnancy. Here, learn more about several common miscarriage misconceptions and the truth behind them.

Myth: Miscarriage is rare

Truth: Miscarriages are not rare. About 10 percent of known pregnancies end in miscarriage, though the number of total miscarriages is likely higher. That’s because many people have a miscarriage very early in the pregnancy before they realize they are expecting and mistake the miscarriage for their menstrual period.

Myth: Exercise can cause a miscarriage

Truth: Exercise will not cause a miscarriage. In fact, regular exercise during a pregnancy is important. However, you may need to take precautions to avoid injuring yourself.

Talk with your doctor about the healthiest way to continue getting movement while you’re expecting.

Myth: Bleeding always means you’re having a miscarriage

Truth: Spotting is common in the early weeks of a pregnancy. If you experience bleeding, talk with your doctor about what is normal and what is a possible sign of miscarriage.

Myth: A miscarriage is the mother’s fault

Truth: The majority of miscarriages occur early in a pregnancy and are the result of a chromosomal abnormality. This is the fault of neither parent.

Myth: Certain foods can cause a miscarriage

Truth: If you’re expecting, there are certain foods you should avoid because they may contain harmful bacteria that can increase risk for miscarriage, such as Listeria and Salmonella. Food to avoid include:

  • shellfish
  • raw fish (such as sushi)
  • undercooked or raw meat
  • processed meats (such as hot dogs and lunch meat)
  • unpasteurized milk and cheese
  • raw eggs

In almost every case, a miscarriage cannot be prevented. It’s most likely the result of a chromosomal abnormality that prevents the fetus from developing properly.

Repeated miscarriages are not common. Only about one percent of people will have a second miscarriage after having a first. If a specific cause for a miscarriage is identified, your doctor can help you treat the condition to prevent a future pregnancy loss.

Taking care of yourself and trying to maintain a healthy pregnancy through diet, exercise, and regular prenatal checkups can help reduce your risk of a miscarriage.