Covid Booster Pregnancy Side Effects

COVID-19 vaccines have been approved for emergency use in the United States. Both vaccines that are currently available, produced by Pfizer/BioNTech and Moderna, are mRNA vaccines. COVID-19 vaccines are not live-virus vaccines; they contain no infectious material, cannot cause a person to develop COVID-19, and cannot cause pregnancy or infertility.

To determine whether vaccination is safe in women who may become pregnant, the vaccine was tested in animal models and found not to harm fetal development. The Centers for Disease Control (CDC) has given the OK to receive vaccination while pregnant because it’s “critical” pregnant women are protected from COVID-19 due to their increased risk of severe illness if infected with SARS-CoV-2 during pregnancy; however, there is limited information on the safety of COVID-19 vaccines in pregnancy overall.

Pregnancy has not been established as a risk factor for COVID-19, but there is no data on the safety and efficacy of COVID-19 vaccine in this population yet.

Pregnancy has not been established as a risk factor for COVID-19. However, there is no data on the safety and efficacy of COVID-19 vaccine in this population.

Taking COVID-19 vaccine during pregnancy may cause side effects.

While the vaccine has not been approved for use in pregnant women, pregnancy has not been established as a risk factor for COVID-19. However, there are no data on the safety and efficacy of COVID-19 vaccine in this population because it hasn’t been studied in pregnant women. There is also a lack of data on how much virus can be transferred from mother to baby during pregnancy and breastfeeding.

Because there aren’t any studies that show how COVID-19 could affect your baby during pregnancy or breastfeeding:

  • You should not get the shot if you are pregnant or plan to become pregnant within 30 days after getting it (unless your healthcare provider tells you otherwise). If someone asks if they should get vaccinated while they are pregnant, they should ask their doctor first before starting or continuing with their vaccination schedule.

SARS-CoV-2 (COVID-19) vaccines that contain mRNA technologies or use adenoviral vectors are expected to be safe and effective, but there are limited data on the safety of SARS-CoV-2 (COVID-19) vaccines in pregnant women.

SARS-CoV-2 (COVID-19) vaccines that contain mRNA technologies or use adenoviral vectors are expected to be safe and effective, but there are limited data on the safety of SARS-CoV-2 (COVID-19) vaccines in pregnant women.

  • Pregnant women should not receive any live attenuated influenza vaccine (LAIV).
  • Women who receive LAIV should avoid becoming pregnant during the influenza season and for 2 weeks after vaccination.

Pregnancy has not been established as a risk factor for COVID-19, but it is important to note that severe outcomes have been reported in pregnant women with COVID-19.

Pregnancy has not been established as a risk factor for COVID-19, but it is important to note that severe outcomes have been reported in pregnant women with COVID-19. If you are pregnant, please consult your healthcare provider before getting vaccinated with the Covid Booster vaccine.

The use of Covid Booster during pregnancy should be considered only if clearly needed after weighing benefits and risks. The decision to get vaccinated with the Covid Booster during pregnancy should be made in consultation with your healthcare provider.

It is unknown whether maternal immunization with SARS-CoV-2 (COVID-19) vaccines will protect infants against COVID-19 due to SARS-CoV-2 exposure after birth.

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The recommendation follows guidance from CDC’s Advisory Committee on Immunization Practices (ACIP) and the American College of Obstetricians and Gynecologists (ACOG).

In the U.S., the decision to vaccinate against group B strep is made by a woman’s health care provider. CDC’s Advisory Committee on Immunization Practices (ACIP) and the American College of Obstetricians and Gynecologists (ACOG) recommend that all pregnant women be tested for GBS during each pregnancy, regardless of their previous test results or whether or not they received a previous vaccine dose. The recommendation follows guidance from CDC’s ACIP and ACOG, which are the main organizations for vaccine recommendations in this country. These organizations base their guidance on scientific evidence available at the time these recommendations are made.

Vaccination should be delayed if the patient has tested positive for current COVID-19 infection, until two weeks after recovery from the acute illness unless laboratory studies confirm recovery and resolution of infection.

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Covid Booster Pregnancy Side Effects

Pregnancy has not been established as a risk factor for COVID-19. SARS-CoV-2 (COVID-19) vaccines that contain mRNA technologies or use adenoviral vectors are expected to be safe and effective in pregnant women.

Earlier, we looked at Covid Booster Pregnancy Side Effects, now let’s look at the whether or not it’s safe to give this vaccine during pregnancy.

According to the Centers for Disease Control and Prevention (CDC), “Pregnant women should not get this vaccine because no studies have been done in pregnant women”. The CDC also warns that it may be more difficult for a pregnant woman to fight off any infections caused by viruses like influenza during her pregnancy.


Ultimately, the decision to vaccinate during pregnancy should be made by the pregnant individual and their healthcare provider. CDC’s Advisory Committee on Immunization Practices (ACIP) is working with the COVID-19 vaccine advisory committee to provide guidance for pregnant people about COVID-19 vaccines. This process will continue to evolve as additional data becomes available.

Covid Booster Pregnancy First Trimester

a photo of a woman touching her pregnant belly showing her vaccine bandaid

Photo: iStock/stefanamer

If you’re pregnant and have had two COVID-19 vaccines, you’ve likely been told to get boosted right away. If you haven’t gotten it, and it’s because you still have some questions, here are some answers, courtesy of Toronto’s Dr. Tali Bogler, a family medicine and obstetrics provider and co-founder of Pandemic Pregnancy Guide (a must-follow on Instagram).

Should people get a COVID booster while pregnant? How should pregnant people space out their COVID vaccines?

We’re recommending that all individuals who are pregnant, as well as those trying to become pregnant, should receive all COVID-19 vaccination doses, including a booster dose.

Exactly when pregnant individuals are eligible to receive their booster (third dose) depends on the province. In Ontario, it’s three months after their primary series. In BC, doctors are recommending pregnant people get the booster eight weeks after their dose.

Is there a best trimester to get boosted?

The best time to get your vaccine or booster dose is now, regardless of gestation. That’s the best way to protect your pregnancy and fetus, given adverse outcomes associated with COVID-19 infection in pregnancy, including preterm birth.

Studies have found that pregnant people who are fully vaccinated (with two doses of an mRNA vaccine or one dose of Johnson & Johnson) transmit antibodies to newborns during pregnancy, regardless of the timing of their vaccine (i.e. whether vaccinated in 1st, 2nd or third trimester).

A study published in the Journal of Obstetrics and Gynecology showed that a booster dose was associated with the highest maternal and umbilical cord antibodies levels. In this study, the booster was given in the third trimester, but a sustained response is expected in other trimesters as well.

Furthermore, multiple studies show that the vaccine in first-trimester is not associated with increased risk of miscarriage, and when received in the second and third trimester, is not associated with increased risk of preterm birth, still birth, small for gestational age, or congenital abnormalities.

Some pregnant people wonder if the booster is overdoing it—like that there might be some sort of cumulative effect of the vaccine and that two shots are enough. Could there be any truth to this?

We know that our immunity wanes over time, so there is no cumulative effect of the vaccine. This is why we often see multiple-dose vaccines series routinely in children, teenagers and adults.

Does it matter which shot you get? Should pregnant people request one shot over the other?

An mRNA vaccine (either Pfizer or Moderna) is recommended in pregnancy. It doesn’t matter which one—both are safe and effective in pregnancy or breastfeeding and elicit a good immune response.

Do pregnant people have worse outcomes than people who aren’t pregnant if they do get COVID during this Omicron wave?

We don’t have published data yet on outcomes with Omicron specifically in pregnancy. Omicron is still so new. What we know in general is that pregnancy is a high-risk population for many serious COVID-19 complications, including hospitalization and ICU admissions, compared to non-pregnant age-matched peers, and is associated with twice the average risk of preterm birth.

Since antibodies from the vaccines wane over time, shouldn’t pregnant people consider waiting until the last trimester to get their vaccine so their baby has the most protection?

The primary goal has always been to protect the pregnant mom from COVID-19 complications and for that reason, they should get their booster whenever they are eligible.

A secondary benefit of the vaccine is that antibodies will be passed to the infant. There’s a study that looked at anti-COVID antibodies in infants who were two months old and six months old from mothers who were vaccinated during pregnancy. Most were vaccinated at the end of the second trimester with two doses of the vaccine. In the vaccinated group, 94% of infants had antibodies at two months, and 60% had antibodies at 6 months. This is compared to only 8% of babies in babies whose mothers had “COVID infection at the six-month mark.”

There’s another study that shows that pregnant people who were vaccinated even six weeks before they became pregnant had anti-COVID antibodies in the cord blood.

Right now, we’re seeing an uptick in hospitalized infants with COVID in Ottawa and at SickKids in Toronto. Vaccination in pregnancy will help protect your babies when they’re born, regardless of when you got vaccinated in your pregnancy. This is exactly why we give the whooping cough vaccine in pregnancy and we see the same for the flu vaccine. It is well-studied in flu and whooping cough that maternal antibodies from vaccination during pregnancy provide protection to the baby for six months of a child’s life.

What are the primary concerns of your pregnant patients who are hesitant to get vaccinated or boosted? 

Most people who are hesitant seem to be worried about the lack of long-term data of the vaccine. They usually have no specific ideas about what could happen down the road, but they are worried that something could.

I usually answer this by first saying “of course we want more data, rather than less.”

But what we know is that mRNA vaccines have been studied in humans since 2013 with no known long-term effects. The mRNA in the COVID-19 vaccine is broken down by the body in two to three days, and the protein may stay in the body for up to two to three weeks. Any potential side effects tend to happen in the first six weeks. We also have studies demonstrating that the mRNA vaccine itself does not cross the placenta—it’s the maternal antibodies that cross the placenta.

When my patients ask me about long-term implications on the baby, I remind them to think about the long-term health implications associated with preterm birth, for which the risk doubles if you’re unvaccinated and contract COVID in pregnancy.

We also have excellent long-term data from other vaccines that we routinely give in pregnancy, like the flu vaccine and the whooping cough vaccine. Studies that have followed children for the first three to six years of life have found no adverse health outcomes in the children.

The other concern from pregnant patients is that there isn’t enough data on the effect of the vaccine in pregnancy on the fetus. But we actually have a lot of safety data at this point. More than 180,000 pregnant individuals have been vaccinated in the USA, and 100,000 in the UK, with no safety concerns appearing in reporting. 14 large studies from five different countries (including data from Ontario) with a total of 135,103 people vaccinated in pregnancy have found no increased risk of miscarriage, preterm birth, stillbirth, SGA (small for gestational age) or congenital abnormalities.

On the other hand, COVID-19 infection in pregnancy is associated with adverse maternal and pregnancy outcomes including increased need for hospitalization, ICU admission, stillbirth and preterm birth.

The bottom line is, the COVID-19 vaccine is safe in pregnancy, but a COVID-19 infection is not.

The Children’s Hospital of Eastern Ontario (CHEO) recently said it was seeing an alarming trend of infants getting COVID after being born to unvaccinated mothers. What are your thoughts on that?

CHEO is tracking the vaccination status of mothers whose infants were admitted to hospital with COVID, and found that all the admitted infants’ mothers had not been vaccinated. Infants are especially at risk because they have an immature immune system that has difficulty combating disease. And if the mother has not been vaccinated against (or infected with) COVID-19, they do not have the protection of maternal antibodies transferred during the third trimester of pregnancy. It is well-studied in other infectious diseases, such as flu and whooping cough, that maternal antibodies resulting from vaccination provide protection for the first six months of a child’s life. And we now have some research that with COVID-19 vaccination, antibodies last in the infant for the first three to six months of life  as well.

I think it’s an excellent example of why it’s so important to get vaccinated and boosted during pregnancy. Not only will it protect you during your pregnancy, but it can also protect your baby in the first few months of life.

If a pregnant person gets vaccinated after the baby is born, will protective antibodies get passed through breastmilk?

Many studies have shown that when you get vaccinated while breastfeeding, there are antibodies in your breastmilk that get passed along to the baby. But, there is a difference in the antibodies delivered to the baby through the placenta when pregnant and the antibodies in breastmilk.

Generally speaking, antibodies that are transferred through the placenta are more effective and longer lasting. Called IgG antibodies, they can last up to three to six months, as compared to IgA antibodies from your breastmilk, which coat your baby’s mouth, nose and gut. They get sloughed off as your baby coughs or sneezes. Next time you feed, they will get topped up, but you will have to continue feeding the baby with breastmilk to continue having that protection.

So if you didn’t get vaccinated in pregnancy and you are postpartum now or breastfeeding, please go get vaccinated. It’s not too late, and by protecting yourself and all eligible members in your household, you are also protecting your baby.

Pros and Cons of Covid Vaccine While Pregnant

2020 was a year of surprises and adjustments for 33-year-old pediatric nurse Kristina Himmer. First came the global pandemic. For the last year, Himmer has worked at Boston Children’s Hospital as a cardiac Intensive Care Unit (ICU) nurse. As she settled into this new way of life, another surprise arrived in the late summer: Himmer found out she was pregnant with her second child.

“I really could get COVID-19 at work; it’s very easy for me to get it,” Himmer said. “Tons of my coworkers have gotten it. [After becoming pregnant], I just had to implement some changes to the way that I work: I don’t take my mask down when I’m around other people. I eat by myself. I just isolate myself at work because my risk is so high.”

In December 2020, Himmer was among the first healthcare workers offered the newly approved COVID-19 vaccine. But for Himmer, there was one problem — the vaccine had not been studied in the pregnant population. Expectant mothers were excluded from the initial COVID-19 clinical trials.

As a result, there is currently no research about the vaccine’s effects on mothers or developing fetuses. The CDC says that vaccination is a “personal choice” for each pregnant person, leaving families to weigh the pros and cons for themselves.

Too Many Questions, Not Enough Answers

As a nurse, Himmer knew the risks of contracting COVID-19 while pregnant. 

“One of the biggest things they say is that if you’re pregnant and you get COVID-19, you have a higher chance of being on a ventilator,” Himmer said. “When you’re pregnant, your immune system is down; it’s harder to fight infections.”

According to the CDC, pregnant people with COVID-19 have an increased risk of severe complications. This includes a greater likelihood of ICU admission, mechanical ventilation and death compared to non-pregnant women of the same age.

Some states, including Massachusetts, have listed pregnancy as a high-risk condition in their vaccination plans. An expectant mother in Massachusetts can get the vaccine in Phase 2. 

But for some mothers, the lack of data about the vaccine’s impact on a developing child was a nonstarter. 

After speaking with her OB/GYN and a maternal-fetal medicine specialist, Himmer decided not to get the vaccine before giving birth in March.

“I’ve done a decent amount of research and I honestly think that the vaccine probably is very safe,” Himmer said. “All of the mRNA vaccines have been very safe for pregnant people. But, I just couldn’t get over the fact that if I got this vaccine and something happened, I would feel so terrible and have this awful regret.”

Vaccine Hesitancy on a Global Scale

The majority of pregnant people in the United States have concerns about the COVID-19 vaccine safety.

In late 2020, the Human Immunomics Initiative at the Harvard T.H. Chan School of Public Health conducted a survey of 17,000 women across 16 countries. Given a 90% vaccine efficacy rate, 73% of non-pregnant women said they would get the shot. This number dropped to 52% for pregnant women.

Julia Wu was the principal investigator for this study. She said expectant mothers wanted to see more data from public health officials, especially in regard to the vaccine’s impact on fetus development.

“[The women in the study] cited [vaccine-related fear due to] the possibility of any harm to their fetuses and they were afraid that the approval might be rushed because of political reasons,” Wu said. “They also felt that there was not sufficient pregnant women-related evidence.”

The vaccine acceptance among expectant mothers was especially low in the United States. Less than 45% of pregnant respondents were open to getting the vaccine. Vaccine acceptance was highest in countries such as India, the Philippines and several Latin American countries.

Wu attributed this difference to the U.S. citizen’s relative inexperience with infectious diseases.

“We have been so successful with a lot of other infectious diseases in comparison to a lot of the middle-income countries, so we became less familiar with the horror of infectious diseases until now,” Wu said. “The developing countries [also] tend to tolerate a little more risk in terms of the vaccine simply because they have more at stake.”

Making a “Personal Choice”

Lawyer and expectant mother Amanda Risch, 33, consulted with her OB/GYN and fertility clinic doctor to learn more about the COVID-19 vaccine.

Risch is not due until July and continues to meet with clients in her downtown Boston office. Because of her exposure to the public and summer due date, she plans to get the COVID-19 vaccine before giving birth. 

“All the science indicates that the risks that come along with getting COVID-19 [for] a pregnant mother are more than some of the speculative risks that come along with getting the vaccine,” Risch said.

Risch said her decision was also influenced by the stage of her pregnancy. 

“The fact that I am at the halfway point also impacts my decision, as opposed to if this was the first trimester when things are so unstable in a pregnancy,” Risch said.

According to Dr. Anthony Fauci, 20,000 pregnant people have chosen to receive the COVID-19 vaccine since December. While expectant mothers have reported no health problems, there is no conclusive research about the vaccine’s impact on a developing fetus. 

New research on the vaccine is in the early stages. On Feb. 18, Pfizer announced a clinical trial to study its COVID-19 vaccine in pregnant people. Until more data is available, public health officials’ advice is clear: The decision to get the COVID-19 vaccine while pregnant is a personal choice for each expectant mother.

Babies Born After Covid Vaccine

This sheet is about COVID-19 vaccines in pregnancy and while breastfeeding. This information should not take the place of medical care and advice from your healthcare provider.

What is COVID-19?

COVID-19 (short for Coronavirus Disease 2019) is an illness caused by a virus (called SARS-CoV-2). The virus easily spreads from person to person through respiratory droplets that come from our mouths and noses when we breathe, talk, cough, or sneeze. For more information on COVID-19, please see the MotherToBaby fact sheet at

What are COVID-19 vaccines?

COVID-19 vaccines help protect against the virus that causes COVID-19. Three different COVID-19 vaccines are currently approved for use in the United States: two messenger RNA (mRNA) vaccines (Moderna/Spikevax® and Pfizer/Comirnaty®) and a viral vector vaccine (Johnson & Johnson/Janssen). None of these vaccines contain live virus that could cause COVID-19. Since the protection provided by the vaccines starts to decrease over time, booster doses are recommended. COVID-19 vaccines and booster doses are not 100% effective at preventing infection, but can greatly reduce the chance of getting very sick from the virus.

You can learn more about the different vaccines and booster shot recommendations here:

Are COVID-19 vaccines recommended for people who are pregnant?

Organizations including the Centers for Disease Control and Prevention (CDC), the American Academy of Pediatrics, and the American College of Obstetricians and Gynecologists (ACOG) recommend that people who are pregnant, recently pregnant, planning a pregnancy, or may become pregnant in the future stay up to date on recommended COVID-19 vaccines and boosters.

Having a COVID-19 infection while pregnant increases the chance of severe illness and pregnancy complications. Studies have shown that pregnant people who are vaccinated are less likely to get COVID-19. If they do get COVID-19, they are less likely to get very sick and may have a lower chance of pregnancy complications related to the illness.

Does getting a COVID-19 vaccine make it harder to get pregnant or affect fertility treatments?

There is no evidence that getting a COVID-19 vaccine makes it harder to get pregnant. Several studies of people undergoing in-vitro fertilization (IVF) found that getting a COVID-19 mRNA vaccine did not affect the function of the ovaries (the organ that releases the egg), number of oocytes (immature eggs), hormone levels, or success rates of embryo implantation. The American Society for Reproductive Medicine recommends that people undergoing fertility treatment stay up to date on recommended COVID-19 vaccines and boosters. There is no recommendation to postpone fertility treatment after getting the vaccine or to avoid getting the vaccine after treatment.

I just got a COVID-19 vaccine. How long do I need to wait before I get pregnant?

Since COVID-19 vaccines are not live vaccines, there is no recommendation to wait before trying to get pregnant. In addition, if someone becomes pregnant after getting the first dose of an mRNA vaccine, they can still receive the second dose on time as scheduled.

Does getting a COVID-19 vaccine increase the chance of miscarriage?

Miscarriage can occur in any pregnancy. A study reported no increase in miscarriages among 2,456 people who received  COVID-19 mRNA vaccines before 20 weeks of pregnancy (when a miscarriage can happen). Another study looked at over 105,000 pregnancies and found that those who had miscarriages were no more likely to have gotten a COVID vaccine in the past month than those who did not have miscarriages.

Does getting a COVID-19 vaccine increase the chance of birth defects?

Every pregnancy starts out with a 3-5% chance of having a birth defect. This is called the background risk. A study including more than 2,000 infants born to people who received the Pfizer mRNA vaccine in the first trimester of pregnancy found no increased chance of birth defects.

Fever is a possible side effect of the COVID-19 vaccines. A high fever in the first trimester can increase the chance of certain birth defects. Acetaminophen is usually recommended to reduce fever during pregnancy. For more information about fever and pregnancy, see the MotherToBaby fact sheet about fever/hyperthermia at

Does getting a COVID-19 vaccine in pregnancy increase the chance of other pregnancy-related problems?

Studies involving thousands of people who have given birth after getting COVID-19 vaccines in the second and third trimesters of pregnancy have not found increased risks for pregnancy or newborn complications such as stillbirth, preterm delivery (before 37 weeks of pregnancy), babies born smaller than expected, low Apgar scores, NICU admission, or neonatal death. The majority of people in published studies received mRNA vaccines (Moderna/Spikevax® or Pfizer/Comirnaty®).

Does getting a COVID-19 vaccine in pregnancy affect future behavior or learning for the child?

It will take time to follow the children of people who were vaccinated in pregnancy in order to answer this question. However, based on what is known about these and other vaccines, getting a COVID-19 vaccine is not expected to cause long-term problems for the child.

Does getting a COVID-19 vaccine during pregnancy protect the baby from the virus after delivery?

The antibodies that a person makes after getting the vaccine during pregnancy can pass to the developing baby. Research has shown that getting the vaccine in pregnancy passes more antibodies to the baby than having a COVID-19 infection in pregnancy does. In addition, a study found that completing the initial two-dose series of an mRNA vaccine during pregnancy significantly lowered the chance of the baby being hospitalized with COVID-19 in the first 6 months of life. The same study found that the majority of those infants who were hospitalized with COVID-19 were born to people who were unvaccinated during pregnancy.

Breastfeeding and COVID-19 vaccines:

Organizations including the Academy of Breastfeeding Medicine and the American Academy of Pediatrics agree that people who are breastfeeding can receive COVID-19 vaccines. There is no recommendation to postpone breastfeeding or discard breast milk after getting the vaccine.

Small studies have found that mRNA from the vaccines is unlikely to enter the breast milk. If any small amounts of vaccine ingredients did enter the breast milk, they would most likely be destroyed in the baby’s stomach. Studies have not reported serious adverse reactions to the vaccine in people who are breastfeeding or their infants. Less than 10% of people have reported changes in milk supply (more or less milk) after getting the vaccine, but their supply returned to normal within a day or two.

Antibodies against the virus that causes COVID-19 have been found in the breast milk of people who have been vaccinated. More research is needed to know if these antibodies might protect a breastfeeding child against the virus and how long that protection might last. Talk to your healthcare provider about all of your breastfeeding questions.

If a male gets a COVID-19 vaccine, could it affect fertility (ability to get partner pregnant) or increase the chance of birth defects? 

Two studies found no differences in sperm production before and after getting a COVID-19 mRNA vaccine. In general, exposures that fathers or sperm donors have are unlikely to increase risks to a pregnancy. For more information, please see the MotherToBaby fact sheet Paternal Exposures at

MotherToBaby is currently conducting an observational study looking at certain COVID-19 vaccines in pregnancy. If you have been vaccinated against COVID-19 and are interested in taking part in this study, please call 1-877-311-8972 or sign up at

Please click here to view references.

OTIS/MotherToBaby recognizes that not all people identify as “men” or “women.” When using the term “mother,” we mean the source of the egg and/or uterus and by “father,” we mean the source of the sperm, regardless of the person’s gender identity.


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