Can COVID-19 Cause a Miscarriage?

There are always things to worry about when you are pregnant, but the COVID-19 pandemic has added an extra layer of stress. Many pregnant people are concerned what may happen if they get infected with COVID during pregnancy—in particular, whether a COVID infection could increase their risk of miscarriage.

This is a reasonable concern, especially given preliminary research that has shown more severe COVID outcomes in pregnant people, including increased risk of miscarriage, pregnancy complications, preterm birth, and neonatal loss. But it’s not all gloom and doom: there are things you can do to reduce your risk—most notably, getting vaccinated against COVID, which has shown to be effective at reducing severe pregnancy outcomes.

We reached out to experts to help us understand the evolving research on COVID-19 and miscarriage, as well as some tips for staying safe and reducing risk during pregnancy.

COVID-19 and the First Trimester

Some of the headlines about COVID and miscarriage may sound alarming. For example, a 2022 study published in Human Reproduction found an increased risk of miscarriage in the first trimester of pregnancy among people who became infected with COVID. The study researchers found that the rate of miscarriage was about 1.7 times higher for people who tested positive for COVID during pregnancy than those who did not.

But before you panic, there are a couple of factors to keep in mind. Stephanie Zeszutek, DO, FACOG, RPh, clinical associate professor at Touro College of Osteopathic Medicine, says that we need to remember that everything we know about COVID and pregnancy is still new.

“It is still unclear about the full impact of COVID-19 on pregnancy,” she notes. “Although some of the studies are limited and are ongoing, what we know right now is that if you are pregnant, you have a higher risk of severe illness from COVID-19 than people who are not pregnant, especially if you have underlying health conditions.”

Furthermore, miscarriages in the first trimester are unfortunately common, whether you have COVID-19 or not, says G. Thomas Ruiz, MD and OB/GYN lead at MemorialCare Orange Coast Medical Center. As such, it may be difficult to know for sure whether COVID caused you to miscarry during the first trimester.

“In general, we believe the baseline risk of miscarriage is up to 20% of pregnancies,” Dr. Ruiz explains. About half of all miscarriages are thought to be due to chromosomal abnormalities, he says. The rest are likely to due uterine issues (fibroids, polyps) along with medical issues such as diabetes, hypertension, and autoimmune disorders.

As for how COVID-19 might come into play during the first trimester, Dr. Ruiz says that some of the increased risk may have to do with the inflammatory response that COVID can cause in some individuals, and how that could affect the placenta. “COVID can cause a whole body inflammatory response, which affects placental function in a bad way,” Dr. Ruiz describes. “Inflammation of the placental will cause infarction, meaning poor oxygenation to a developing embryo, leading to miscarriage.”

COVID-19: The Second and Third Trimester

There are some concerns about how COVID might affect the middle and end of pregnancy. Some of this info is also unsettling, but it's again important to keep things in perspective, and understand that these poor outcomes are rare. Not only that, but our understanding of how COVID affects pregnancy is still evolving, and is affected by different variants of the virus, as well as whether or not you are vaccinated.

As the CDC reports, severe pregnancy complications have been seen in individuals infected with COVID during the second and third trimesters of pregnancy. For example, pregnant people are more likely to deliver preterm (before 37 weeks) if they get COVID during pregnancy. Pregnant people with COVID are also more likely to be hospitalized and need ICU care including ventilation, both of which can put their baby at risk.

Studies have also linked COVID infection with stillbirth and neonatal loss. A CDC study that looked at pregnancy outcomes from March 2020 to September 2021 found a connection between COVID positive pregnant people and stillbirth, especially during the period when the delta variant was widely circulating. Stillbirth was more likely to occur in pregnant people who were hospitalized with COVID complications, the study researchers point out. Inflammation and reduced blood flow to the placenta caused by COVID may also lead to these tragic outcomes, they add.

Dr. Ruiz agrees that these factors may contribute to the increased risk of pregnancy loss. “Second trimester miscarriages are rare, but if the placenta is compromised due to an inflammatory response, this can compromise the pregnancy,” he says. We also know that certain viruses (parvovirus, rubella, chickenpox) can lead to fetal demise, Dr. Ruiz describes. “We don’t have enough information about COVID to know if that is an issue,” he says.

When to Contact Your Healthcare Provider

Any time you are showing a signs of miscarriage during pregnancy, you should get in touch with your healthcare provider. The signs of miscarriage during a COVID infection would be similar to any type of miscarriage, and aren’t specific to COVID, says Dr. Zeszutek.

“The most common signs of a miscarriage are bleeding with or without pain, gush of fluid, or passage of tissue from the vagina,” she describes. According to the CDC, red flags to watch for during the second and third trimester of pregnancy—whether you have COVID or not—include vision changes, dizziness/fainting, fever, extreme swelling, trouble breathing, decreased fetal movement, and unexplained bleeding.

How Can I Lower My Risk?

Thankfully, we are in a much better place with COVID than we were at the beginning of the pandemic, or even when some of the studies about COVID and pregnancy were first done. We now have vaccines that are safe and effective at preventing the most serious COVID outcomes, during pregnancy or otherwise.

Indeed, a 2022 study published in Nature that looked at neonatal loss among vaccinated vs. unvaccinated parents found that vaccines were highly protective. The vast majority of pregnancy complications, critical care admission, and infant deaths occurred among unvaccinated individuals, the study concluded.

Dr. Ruiz agrees that vaccination is the best way to keep yourself safe from the increased risks of miscarriage and pregnancy loss during the pandemic.

“Vaccinated patients who get breakthrough infections get less sick, [and] will not get that big inflammatory response,” he says. Dr. Ruiz also pushes back against the notion that COVID vaccines are unsafe during pregnancy. “Strangely enough, many women trying to conceive have this false conception that the vaccine creates a situation where it’s more difficult to get pregnant; this data has not been shown to be true."

"Vaccination isn’t just important in terms of protection during pregnancy, but antibodies from your vaccine are passed on to your baby and offer them protection after birth," says Dr. Zeszutek. In addition to staying up to date on your vaccines, she says that practicing other common sense precautions also makes sense.

“Check in with your health care team regularly and follow guidelines from health officials to avoid exposure,” Dr. Zeszutek suggests. “Prevention measures such as hand washing, physical distancing, and wearing a mask can apply to protection from other viruses as well, and should be part of a daily routine.”