Most Common Factors That Contribute to First Trimester Miscarriage

upset woman talking with healthcare provider about a miscarriage

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Experiencing a first trimester miscarriage can be a challenging experience. And one of the most difficult aspects of this type of loss can be determining exactly what went wrong or why it happened.

But, as Anita Somani, MD, an OB/GYN with Ohio Health Physician Group points out, "Conception is not a perfect process."

If you are wondering why first trimester miscarriage may happen or what factors might influence it, be sure to read on. We turned to some experts to examine the signs and symptoms, the factors and risks that contribute to early pregnancy loss, as well as some of the myths surrounding miscarriages.

What Is a First Trimester Miscarriage?

First trimester pregnancy loss—also referred to early pregnancy loss or spontaneous abortion—is generally defined as a nonviable intrauterine pregnancy. These types of losses, while discouraging, are fairly common occurrences in early pregnancy.

"First trimester pregnancy loss is defined as pregnancy loss up to 12 weeks and six days," explains Hongmei Meng, MD, an OB/GYN at Altos Oaks Medical Group at Stanford Medicine Children’s Health. "[It's also important to note] that miscarriage is nobody's fault."

As many as 26% of all pregnancies end in miscarriage while up to 10% of clinically-recognized pregnancies end in miscarriage. Meanwhile, experts estimate that 80% of early pregnancy loss occurs in the first trimester, with the risk of miscarriage decreasing after 12 weeks gestation.

Hongmei Meng, MD

Miscarriage is nobody's fault.

— Hongmei Meng, MD

"First trimester miscarriage is common and you don't have to suffer in silence—you are not alone," says Maximilian Klein, MD, a board-certified OB/GYN practicing reproductive endocrinology for Boston IVF in the Syracuse location. "The silver lining is that the likelihood of being able to have a live birth is very very good. Within about a year or year and a half of trying, there is a 75% percent chance they will get pregnant and stay pregnant—and it almost always ends in live birth."

Symptoms of First Trimester Miscarriage

There are very few signs or symptoms of first trimester pregnancy loss. According to Dr. Klein, vaginal bleeding, pain, and pelvic cramping are the most common signs of an impending loss.

"Sometimes there are no symptoms at all," he adds. "The miscarriage might be found coincidentally at an appointment when you discover there is no heartbeat."

Although bleeding is the most common sign of miscarriage, it is important to remember that spotting and even a small amount of bleeding early in pregnancy can be common. It also does not necessarily mean that you will have a miscarriage.

Still, if you experience spotting or a small amount of bleeding in pregnancy, talk to your healthcare provider. If your bleeding is heavy or happens with pain, contact your provider right away.

Factors That Contribute to First Trimester Miscarriage

When it comes to understanding why first trimester miscarriages occur, it can be helpful to know what factors contribute to them. While most of the time, the exact cause of the miscarriage may never be known, researchers have identified some possible reasons. Here is what the science says about what may cause a first trimester miscarriage.

Chromosomal Abnormalities

Chromosomal abnormalities are the most common cause of early miscarriage, says Dr. Somani. In fact, research indicates that chromosomal abnormalities account for 50% to 70% of miscarriages in the first trimester, particularly those that are less than 10 weeks gestation.

"Any time there are too many or not enough chromosomes, there is a risk for miscarriage," Dr. Somani says.

For instance, when the embryo is missing a pair of chromosomes (nullisomy) the embryo cannot develop in a healthy way and will likely result in a miscarriage. Likewise, when there is one chromosome missing (monosomy), the pregnancy will almost always result in a miscarriage.


Research suggests that preventable infections can account for up to 15% of early miscarriages. While it is not fully known how or why infections cause miscarriage, there are a number of infections that can contribute to first trimester miscarriage. Some examples include cytomegalovirus (CMV), mycoplasma, chlamydia, ureaplasma, listeria, or toxoplasmosis.

That said, it important to note that not all infections will lead to miscarriage, and, with effective treatment, the likelihood of a miscarriage can be significantly reduced. For this reason, pregnant people are often offered the TORCH panel test on their first pregnancy screening visit. (TORCH stands for toxoplasmosis, other agents, rubella, cytomegalovirus, and herpes.)

"The TORCH test screens for a group of infections that are likely to cause pregnancy complications, including miscarriage," says Dr. Klein.

Underlying Medical Conditions

The likelihood of a miscarriage is increased if an underlying health condition is undiagnosed or poorly managed, Dr. Klein says.

If you have any ongoing medical conditions like diabetes, high blood pressure, or an autoimmune disease, it is important to talk to a healthcare provider about your current treatment plan—including the use of medications—to see if it needs to be adjusted before you get pregnant.

"If a [pregnant person] has an underlying issue like autoimmune disease or diabetes, this increases the risk of miscarriage," Dr. Klein explains. "But once you get the underlying medical condition under control, you should be able to reduce to the baseline risk of miscarriage. However, even if you optimize what is going on [and the condition is managed], there is still a residual risk of miscarriage in any pregnancy."

Other Contributing Factors

  • Hormone issues including low levels of progesterone or a thyroid problem
  • Health conditions like lupus or polycystic ovary syndrome (PCOS)
  • Problems inside the uterus such as scar tissue, an abnormal shape, or fibroids
  • Injury or trauma
  • Exposure to toxic substances and chemicals

Who Is at Risk for a First Trimester Miscarriage?

There also are some lifestyle factors that can increase the risk of miscarriage—though they are not necessarily the cause. In fact, according to the American College of Obstetrics and Gynecologists (ACOG) first trimester miscarriage is rarely the pregnant person's fault.

That said, some factors can increase the risk of miscarriage like substance abuse, smoking, excessive amounts of caffeine, trauma, and malnutrition.

Another factor that increases the risk of miscarriage is the pregnant person's age. For instance, in people 20 to 30 years old, the risk of miscarriage is 8.9%. But this risk increases to 74.7% for people over age 40.

Obstetrical history is another important predictor of early pregnancy loss. In fact, the risk of miscarriage increases to 28% after two consecutive miscarriages and 43% after three more consecutive miscarriages. But even though all of these factors increase the risk of miscarriage, experts indicate that there is no one predictor of future pregnancy loss.

"[It is important to] talk to your OB/GYN prior to conception to have preconception counseling," suggests Dr. Meng. Together, you can discuss your risk factors, underlying medical conditions, and your obstetrical history.

Myths About First Trimester Pregnancy Loss

When a pregnancy ends unexpectedly, it can not only be an overwhelming but it also can be easy to blame yourself. In fact, a national survey found that people who had experienced a miscarriage often felt that they had done something wrong.

Many times, these feelings are fueled by a number of myths surrounding miscarriage. Here are some common miscarriage myths that people often wrongly believe.

Myth: You Have to Wait to Get Pregnant After a Miscarriage

In most cases, it's safe to start trying to get pregnant again as soon as you feel physically and emotionally ready, says Dr. Somani. There is no medical reason that indicates that it is not safe to get pregnant right away.

"I tell patients they can try when they are emotionally ready, because physically they can be ready after one cycle," Dr. Somani says. "There is no data to support delaying conception. It really just depends on the person."

Myth: Multiple Miscarriages Mean You Are Infertile

First trimester pregnancy loss is usually a one-time event with most people going on to have successful pregnancies. In fact, recurrent miscarriages are rare and not necessarily a sign of fertility issues.

"Having recurrent miscarriages is not the same as infertility," says Dr. Somani. "It just might mean you are not able to carry the pregnancy."

If you have had multiple first trimester miscarriages, it might be helpful to see a reproductive endocrinologist to see if there is another cause for the miscarriages, Dr. Klein says. In some cases, there may be a structural issue in the uterus or an undiagnosed medical condition that is increasing the risk of miscarriage.

Anita Somani, MD

I like to tell people the silver lining is that you were able to get pregnant. We know a lot of things are working. We know they are able to get pregnant.

— Anita Somani, MD

"[Recurrent miscarriages] have been well studied," he says. "Just 2% of pregnant [people] will experience two consecutive miscarriages—it is very rare to have multiple miscarriages in succession. After two miscarriages, that is when it really increases the likelihood of having a third."

For this reason, testing should be done when two miscarriages happen in a row, Dr. Klein adds, because there may be something that can be done to help. Even when no cause is found, though, most people go on to have successful pregnancies even after repeated miscarriages, he says.

"I like to tell people the silver lining is that you were able to get pregnant," Dr. Somani says. "We know a lot of things are working. We know they are able to get pregnant."

Myth: Stress Causes Miscarriage

Another common myth about miscarriage is that it can be caused by stress or even a heated argument. In one survey, 76% of respondents said that they believed that stress caused miscarriages and 64% said they thought lifting heavy objects could cause pregnancy loss. 

However, these activities—along with depression, exercise, sex, spicy food, or travel—have not been shown to cause miscarriage. Likewise, neither morning sickness nor having taken birth control pills before getting pregnant cause miscarriage. Most of the time, miscarriage is a random event.

A Word From Verywell

Having a miscarriage can be emotionally taxing and can cause you to wonder if you did something wrong. But it’s important to remember that miscarriage is usually a random event and not your fault. Almost always, the reason for the miscarriage is outside of your control.

If you are concerned about a first trimester miscarriage or if you have recently had a miscarriage, it is important to talk to your OB/GYN or healthcare provider about your concerns. They may recommend additional testing and provide suggestions on how to care for yourself emotionally and physically.

And most importantly, be kind to yourself. It is normal to feel anxious or stressed after a miscarriage, but the likelihood of you having a healthy pregnancy is high. If you are worried about your chances, talk to your healthcare provider.

8 Sources
Verywell Family uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial process to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.
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By Sherri Gordon
Sherri Gordon, CLC is a published author, certified professional life coach, and bullying prevention expert.