A large study in Scotland found that unvaccinated pregnant women were more likely to be sick with COVID-19 and more likely to be hospitalized and their babies and fetuses were more likely to die, compared with vaccinated people who had COVID-19 during pregnancy. 

Published in Nature Medicine on Thursday, the study looked at data on roughly 145,000 pregnancies in about 132,000 people from December 2020 to October 2021. While unvaccinated women made up 77.4% of COVID-19 infections during this period, the study says, they also made up 90.9% of hospitalizations and 98.1% of critical care admissions. 

All perinatal deaths (the death of a fetus or newborn within weeks of their birth) following COVID-19 infection of the pregnant person happened in those who weren't vaccinated, the study found. 

The latest published study adds to the growing concern for parents, fetuses and newborns as pregnant people have been less likely to get vaccinated for COVID-19 than other adults. Data confirming the safety of COVID-19 vaccination during pregnancy, however, continues to build.

A report on more than 40,000 pregnancies published last week by the US Centers for Disease Control and Prevention compared preterm birth rates (babies being born too early) and birth weights of newborns in unvaccinated and vaccinated people who mostly got their shots in the second or third trimester. The study found no increased risk of preterm birth associated with the vaccines, and no difference in birth weight between vaccinated and unvaccinated people. 

The CDC recommended booster shots to pregnant people before they recommended them to everyone because, while the overall risk is still low for a group that's typically under age 45, pregnant people are more at risk compared with people of the same age who aren't. Being pregnant recently (within 42 days) also raises your risk, the CDC says. 

But while the CDC's recommendation (get a booster of Pfizer or Moderna) echoes guidance from groups that serve pregnant people and their babies specifically, such as the American College of Obstetricians and Gynecologists and the Society for Maternal-Fetal Medicine, pregnant people were left with unclear guidance at the beginning of the pandemic. True to age-old practices of excluding pregnant people from medical studies, they were left out of initial trials on COVID-19 vaccines. 

But much has happened since the beginning of the pandemic, including the omicron variant that is causing more breakthrough infections and spiking record numbers of COVID-19 cases. And the value of protection against COVID-19 during pregnancy (or before it begins) is becoming even more clear. Here's what to know about COVID-19 vaccines if you're breastfeeding, pregnant or want to be in the future. 

I'm pregnant. Should I get a COVID-19 vaccine? 

The CDC made its official recommendation in August that, yes, pregnant people, breastfeeding people and those who want to be pregnant in the future should get vaccinated against COVID-19. The ACOG and SMFM also recommend COVID-19 vaccines for pregnant people. 

Other vaccines are recommended or offered during pregnancy. Some vaccines, for other diseases, aren't recommended for pregnant people because they contain (very small amounts) of a live virus. None of the coronavirus vaccines available in the US uses a live virus, making them safe during pregnancy.

Do I need a booster if I'm pregnant? Which shot should I get?

With the emergence of the new omicron variant, boosters are recommended for everyone 12 and up in the US, including pregnant people. In fact, while the CDC guidance for the general public was strengthened because of the omicron variant, pregnant people were eligible for boosters earlier, just because of their increased risk of severe COVID-19 compared with people who aren't pregnant. 

You should get a booster of Pfizer's or Moderna's vaccine at least five months after your second Pfizer or Moderna, or at least two months after your Johnson & Johnson shot, according to guidance from the FDA and CDC. Everyone should choose a booster of Moderna or Pfizer, the CDC now says, because of the rare but serious risk of blood clots associated with J&J's vaccine. While rare overall, women ages 30 to 49 are at higher risk following the one-dose vaccine. 

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What are the side effects of the vaccine for pregnant people?

Preliminary data on about 35,000 pregnant people who were vaccinated and volunteered information through the V-safe program shows that pregnant people experience the same vaccine side effects that others have reported: temporary injection pain in the arm, fatigue, headache, muscle aches and fever. 

However, it's important to note that fever from any cause has been associated with adverse pregnancy outcomes, and the CDC recommends pregnant people who experience fever after vaccination take acetaminophen to lower their body temperature. (Fever can also be a symptom of COVID-19.) 

If you have specific questions about the vaccine or you have concerns in general, you can talk to an expert by emailing Mother to Baby or calling 1-866-626-6847. 

Why are pregnant people at a high risk of COVID-19? 

In May, CNET talked to Dr. Ella Speichinger, an OB-GYN at University of Missouri Health Care. She said it isn't exactly known why pregnant people are at a higher risk, but that it may be because pregnant people's immune systems are naturally depressed so that their bodies won't reject the growing fetus, or because pregnancy could alter the body's way of mounting an immune response to COVID-19. 

"I've had many patients who have had COVID while they were pregnant, and they've been just fine," she said. "But there have definitely been severe cases where patients had to get delivered early because they could no longer oxygenate their fetus." 

In these cases, Speichinger said the patients usually improved after giving birth, but that it was delayed. It's also impossible to know who will have a bad reaction to COVID-19 while pregnant. 

"It's really unclear who of the healthy pregnant cohorts is going to be the one that gets sick," she said. 

During what trimester should I get the vaccine?

Scientists who looked at people who got vaccinated earlier than 20 weeks pregnant didn't find an increased risk of miscarriage compared with those who didn't, according to a report from the V-safe pregnancy registry. Earlier data that was available reflected vaccination during the later stages of pregnancy.

It may be that some people hold out on getting vaccinated during the first trimester due to the naturally high rate of miscarriage in the first three months, and patients being more cautious because of that. About 10% of known pregnancies end in miscarriage, according to the ACOG, but the risk also increases with age. About 80% of miscarriages happen in the first trimester. 

"Most people feel concerned in the first trimester because there's such a high risk of miscarriage in general," Speichinger said. "Conflating the miscarriage with vaccine administration is what leads to vaccine hesitancy in the first trimester." 

Research shows that parents vaccinated during the third trimester of pregnancy may pass antibodies onto their newborns.

I'm skeptical of the vaccine. What are the risks of getting COVID-19 while pregnant? 

Pregnant and recently pregnant people are at higher risk of severe illness from COVID-19, including death, according to the CDC, and they're also at increased risk for preterm delivery (birth before 37 weeks) and other adverse pregnancy outcomes including stillbirth. Other health factors of the pregnant person, including a high BMI, diabetes or heart conditions, may elevate this risk, according to the SMFM.

What if I'm breastfeeding? 

"If a woman is uncomfortable doing it while pregnant, I absolutely think getting it while she's breastfeeding is a good idea," Speichinger said. "Because all of those antibodies can then cross through to the milk and protect baby while the mom is still producing those antibodies." 

There's not enough data to show how long that protection lasts, but the CDC reports that breastfeeding people who have received an mRNA vaccine produce COVID-19 antibodies in their breast milk. In a small study on lactating health care workers who received a mRNA vaccine while breastfeeding, researchers from the University of Florida found that their breast milk had a "significant" amount of antibodies. 

In its latest report, the CDC made a strong recommendation that breastfeeding people and those who were recently pregnant get a COVID-19 vaccine.

I want to be pregnant in the future. Will the COVID-19 vaccine make me infertile? 

All available data says the same thing: no. 

The fear about infertility and COVID-19 vaccines stems from a now-debunked post on Facebook that claimed the vaccine would make pregnant people's bodies attack a protein needed for placenta formation in early pregnancy because, it asserted, the spike protein in the COVID-19 vaccine is "similar." Experts have disproved this, saying that not only do the two proteins have "almost nothing in common," but even if they did, infection with COVID-19 would have the same outcome. There is no research to suggest people who have had COVID-19 will have a more difficult time getting pregnant, and many have since the beginning of the pandemic. If you'd like more information about COVID-19 vaccines and pregnancy, Dr. Danielle Jones, an OB-GYN who is also known as "Mama Doctor Jones" on TikTok, shared this video on YouTube debunking myths about COVID-19 vaccines and infertility, miscarriage and pregnancy. 

The information contained in this article is for educational and informational purposes only and is not intended as health or medical advice. Always consult a physician or other qualified health provider regarding any questions you may have about a medical condition or health objectives.