Why Pregnant Women Should Get the COVID-19 Vaccine

On September 29, the Centers for Disease Control and Prevention (CDC) issued an urgent health advisory recommending that women who were pregnant or planning to become so receive the COVID-19 vaccine. The alert was based on findings that not only do pregnant women who catch COVID have worse outcomes than non-pregnant women, they also put their pregnancies at risk.

More than 22,000 pregnant women across the country have been hospitalized with COVID and 161 have died, according to the CDC.

At the same time, as of mid-September, only 31% of pregnant Americans were fully vaccinated, compared to about 56% of all Americans.

Erika Werner is chair of the obstetrics and gynecology department and the Louis E. Phaneuf Teaching and Research Professor of Gynecology at Tufts University School of Medicine. She is also physician-in-chief of obstetrics and gynecology for Tufts Medical Center. She spoke with Tufts Now about why pregnant women are more vulnerable to the virus, why she recommends the vaccine, and what she hears from her patients.

Tufts Now: The CDC recently issued new guidance strongly advising pregnant women to get vaccinated against COVID-19. Had something changed to prompt the urgent alert?

Erika Werner: Early on, some pregnant women were hesitant to get the vaccine because pregnant and lactating women were excluded from the trials that informed the emergency approval of the vaccine. But what we now think—based on population data—is that if you get the COVID virus when you're pregnant, you have an increased risk of morbidity in your pregnancy including an increased risk of preterm birth. Usually this is because of the interventions that have to happen because someone is sick with COVID. So it is really important that pregnant women not get the virus and the best way to not get the virus is to get the vaccine.

There’s no reason that a pregnant woman should not get the vaccine. Vaccine registries have shown that women who get the vaccine during pregnancy have the same rates of complications as other women. Based on all the data we have, it is safer for pregnant women to get the vaccine than not get it.

So the risks from not getting the vaccine are much higher than the risks from getting it?

Absolutely. And if you get COVID and you're pregnant, your risk of ending up in the ICU is higher than if you weren't pregnant.

Why would a pregnant woman react differently to the COVID virus than a non-pregnant woman? Is there something about being pregnant that just makes you more vulnerable?

It’s because as early as the first trimester, your lung volume reserve changes. Your diaphragm moves up in your chest and your extra lung capacity decreases. Any pregnant woman can talk about the shortness of breath they have in the third trimester. If you get a respiratory infection on top that—just any compromise to your lungs is worse in pregnancy. It's the same for the flu. We know that pregnant women who get the flu are also at higher risk for having complications and ending up in the ICU than non-pregnant women.

I also read that during pregnancy, the immune system is depressed. Does that come into play as well?

Pregnancy is definitely an immune-compromised state in some ways. And so that puts pregnant women at higher risk for lots of different infections. This may be why women who get COVID when they are pregnant are at higher risk of serious illness requiring hospitalization.

Have you treated pregnant patients who had COVID?

I think you'd be hard pressed to find any high-risk obstetrician in the country who hasn’t taken care of very, very sick COVID patients, patients who had to be intubated, who were put on ECMO [a machine that pumps and oxygenates the blood]. Many of us have lost patients due to COVID. COVID deaths are tragic no matter when they occur, but when they occur in pregnancy, you're often forced to decide how early to deliver the fetus. Do you deliver the fetus at the end of the second trimester, which is way too early and risks long-term morbidity for the kid, but it might give that mom a fighting chance?

Every pregnant COVID patient that I've had in the ICU has been unvaccinated.

When you talk to pregnant women who are debating whether to get the vaccine, what do they tell you?

Most say, “I'm being really careful because I'm pregnant. I'm healthy. I don't think I'll get it.” And they absolutely bring up that pregnant women were not included in the initial vaccine safety trials, and that is true. I wish they were, but they were not. And they say they want to make it through their pregnancy and then they'll get vaccinated, or they want to finish breastfeeding and then they'll get vaccinated.

And in fact, getting vaccinated now would do more to protect their babies. We know that if pregnant women get vaccinated in the third trimester, antibodies are in the cord blood and in their breast milk after they deliver. And that may help protect their newborn from the virus, much in the same way that we now give people the whooping cough vaccine during pregnancy to protect babies. We really need to help patients understand that giving them the COVID vaccine in pregnancy, if they haven't already received it, not only protects them but may have some benefit for their newborn after birth.

Is there an ideal time during pregnancy to get the vaccine?

As soon as you possibly can.

Women routinely take other vaccines during pregnancy; I remember the first time a doctor recommended a flu vaccine to me was when I was pregnant. How should pregnant women think about the COVID vaccine in relation to those other vaccines they take?

That's one of the first things I bring up with patients. We know that pregnant women are at higher risk for complications from viruses. Are you willing to get the flu vaccine or the Tdap [tetanus, diphtheria, pertussis] vaccine in pregnancy? They're all doing the same thing. They're all taking a vulnerable point in your life and trying to make it a little bit safer.

Does the COVID vaccine affect fertility?

That was a total myth from the start. There is no data that the vaccine changes your fertility. There is some anecdotal data that the stress the vaccine puts on your immune system may cause small changes in the menstrual cycle—breakthrough bleeding for that month. The National Institutes of Health is funding investigations into whether the vaccine or getting COVID itself changes your menstrual cycle acutely, but there is no data that it affects your fertility or increases your miscarriage risk or any of that. Studies in large cohorts have looked at that question. My own daughters both got the vaccine as soon as they could. I have no concerns that it will affect their ability to get pregnant someday.

As you pointed out, pregnant women weren’t included in the initial safety and efficacy trials for the vaccines. What research would you like to see in the future?

The Society for Maternal-Fetal Medicine, the American College of Obstetricians and Gynecologists—we are all advocating loudly that in the future pregnant women need to be included in these vaccine trials, assuming that they want to be, the next time we have a novel virus emerge. In the short term I would like to see more funding go toward following pregnant women who have gotten the vaccine and their short- and long-term outcomes.

But for now, how confident are you in recommending the vaccine for pregnant women?

If I were pregnant today, had I not already had the vaccine, I would be running to get it. I can't say it strongly enough. It's the only way to keep pregnant people safe from the virus.