Contracting COVID-19 During Pregnancy Has Been Linked to Preterm Birth

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Key Takeaways

  • Contracting COVID-19 during pregnancy increases the risk of preterm labor, according to a new study.
  • It was found that BIPOC and Latinx pregnant people experience disproportionately higher outcomes of preterm birth from COVID-19.
  • People who had comorbidities such as diabetes had significantly higher risks of preterm birth if they contracted COVID-19.
  • The vaccine has been deemed safe for pregnancy at all stages and is the most important prevention tool for COVID-19 related preterm birth.

Getting COVID-19 while pregnant can be terrifying enough on its own. But now researchers have identified additional risks for the birthing person and the baby, including preterm birth. Babies are supposed to keep growing for 40 weeks in the womb to achieve the best possible health outcomes, and some stay even longer (up to 42 weeks). But a recent study found an increased risk of preterm birth for parents who had contracted COVID-19 during pregnancy.

What Did the Study Find?

The study, conducted by Deborah Karasek, PhD, MPH, an epidemiologist at the University of California San Francisco, found a significant connection between COVID-19 and preterm birth risk. The researchers classified preterm birth into two categories: very preterm birth (less than 32 weeks) and preterm birth (less than 37 weeks). They concluded that pregnant COVID-19 patients had a 60% increased risk of very preterm birth and a 40% higher risk of preterm birth. 

The risk of preterm birth in the study started to get even more substantial when the researchers examined preterm birth risk in pregnant parents who also had an additional health condition, such as hypertension, diabetes, and obesity. In these populations, the risk of very preterm birth was 160% greater than pregnant people who hadn’t contracted COVID-19.

Like many maternal complication studies, researchers found a disproportionate number of BIPOC and Latinx women were impacted by COVID-19 and related preterm births. Dr. Karasek says, “While Latinx birthing people represented 47% of the overall sample, they represented 72% of the COVID-19 positive cases.”

“Historically, there are implicit and explicit racial biases within the medical system that contribute to disparate outcomes,” she says. “Access to vaccines, testing, and health care resources are also limited in these communities. The hesitancy of getting the vaccine is exaggerated by misinformation in media platforms and fears about the vaccine’s safety.”

Deborah Karasek, PhD, MPH

We saw inequities in the burden of COVID-19 infection in pregnancy among BIPOC birthing people.

— Deborah Karasek, PhD, MPH

Dr. Karasek says this is yet another example of inequities that may result from occupational exposures and structural disadvantage because of racism. Jodie Horton, MD, FACOG, an OB/GYN and clinical assistant professor at Georgetown University Medical Center and Chief Wellness Advisor at Love Wellness, says these communities are already working against inequities in birth outcomes due to racism and biases, which has been further highlighted during the pandemic. She stressed that Black and Hispanic pregnant individuals appear to have disproportionate COVID-19 infection rates, in addition to obstetrical complications and death rates. She points to distrust in the medical community.

Why Does COVID-19 Increase the Risk of a Preterm Birth?

Doctors aren’t entirely sure yet as to why COVID-19 leads to more preterm births. This includes both physician-induced early births to preserve the health of the pregnant person and/or the baby, and also babies who come early on their own.

“We were unable to assess physiological mechanisms for the relationship of COVID-19 infection and preterm birth, but we did see an increased risk for births that arose spontaneously and those that were initiated by providers,” Dr. Karasek says.

Deborah Karasek, PhD, MPH

The hesitancy of getting the vaccine is exaggerated by misinformation in media platforms and fears about the vaccine's safety.

— Deborah Karasek, PhD, MPH

Dr. Horton concurs that the connection is unclear. “Some studies found that COVID-19 infection increased the risk of preterm birth but it is not well understood why,” she says. “Infections can cause preterm labor and birth but it is unclear if COVID-19 is the direct cause of preterm birth.”

What Are the Effects of a Preterm Birth on Baby?

Preterm babies often have health conditions and additional challenges, but most babies born past 34 weeks have the same survival likelihood as full-term infants. Some may experience health complications. One of the most common concerns is that the lungs haven’t fully developed if babies are very preterm or preterm.

“These very early births carry the greatest health risks for infants, including respiratory complications and possible NICU stays,” says Dr. Karasek. “Additionally, these risks are more than doubled among pregnant people with comorbidities of hypertension, diabetes, or obesity.”

Dr. Horton explains that one in 10 babies’ births are preterm, regardless of COVID-19. Pregnant people with the following risk factors already have an increased chance of experiencing a preterm birth:

  • Multiple pregnancies
  • Age
  • Race
  • Infections
  • Additional medical conditions (such as diabetes or hypertension)
  • Obesity (which increased the chances of diabetes or hypertension)

Sometimes, she says, the cause of preterm birth is never identified. 

Preventing COVID-19 During Pregnancy

When the vaccines first came out, medical experts weren’t as sure about recommending them to pregnant people. But now they are encouraging it in every way possible after seeing the potentially devastating effects of COVID-19 during pregnancy. Experts now strongly recommended that people who are pregnant get vaccinated against COVID-19.

“The American College of Obstetrics and Gynecology states that getting vaccinated against COVID-19 is the best method to reduce maternal and fetal complications due to COVID-19 infection,” Dr. Horton says. “The COVID-19 vaccine is safe in all stages of pregnancy, postpartum period, and for breastfeeding moms.” 

Dr. Karasek hopes her study will shed light on the immense importance of vaccination during pregnancy.

“We now know that vaccines are safe, and our study shows the risks of COVID-19 infection in terms of preterm birth,” Dr. Karasek says. “We hope this information can be used by pregnant people and providers to have an open and honest conversation about vaccination that acknowledges concerns and discusses safety and benefits. Vaccinating family members and community members is also an important way to protect pregnant people and babies.”

In addition to getting vaccinated, wearing masks, and frequent handwashing, pregnant people with underlying conditions should stay proactive and up to date with medical care during pregnancy. “If you have comorbidities such as hypertension or diabetes, it is important to have consistent prenatal visits, and maintain good control of your blood pressure and blood sugar levels throughout pregnancy,” Dr. Horton says.

Dr. Karasek wants pregnant people to be able to access safer health conditions that decrease their exposure and increase their odds for a successful pregnancy across all communities. “[We need to] think about other measures that can protect pregnant people from COVID-19 exposure,” she says. “This would include risk mitigation measures, workplace protections, leave in pregnancy, eviction moratoriums, and other public policies that can allow pregnant people to stay safe.”

Dr. Horton hopes pregnant people will work hard to stay as healthy as possible during pregnancy, a time when the immune system is suppressed making people more vulnerable to infection. “There isn’t anything women can do to decrease the risk of preterm birth except to optimize their health before becoming pregnant and getting vaccinated,” she says.

What This Means For You

If you are pregnant, follow medical expert advice and get vaccinated to protect the health of yourself and your unborn child. Recent research has demonstrated that COVID-19 is associated with higher rates of preterm and very preterm births, with an even higher risk if you have an additional condition such as obesity or diabetes. Consistent prenatal care is imperative to staying healthy during pregnancy, with or without COVID-19.

5 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.
  1. Karasek D, Baer RJ, McLemore MR, et al. The association of COVID-19 infection in pregnancy with preterm birth: a retrospective cohort study in CaliforniaLancet Reg Health Am. Published online July 30, 2021. doi:10.1016/j.lana.2021.100027

  2. Centers for Disease Control and Prevention. Preterm birth.

  3. Mayo Clinic. Understand how COVID-19 might affect your pregnancy.

  4. American College of Obstetrics and Gynecology. ACOG and SMFM recommend COVID-19 vaccination for pregnant individuals.

  5. Centers for Disease Control and Prevention. New CDC data: COVID-19 vaccination safe for pregnant people.

By Alexandra Frost
Alexandra Frost is a freelance journalist and content marketing writer with a decade of experience, and a passion for health and wellness topics. Her work has been published in the Washington Post, Glamour, Today's Parent, Reader's Digest, Parents, Women's Health, Business Insider, and more.