COVID Vaccine in Pregnancy

Jun 10, 2021

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Why does COVID-19 matter to a pregnant woman?

  • Because you are at higher risk of adverse health outcomes, such as need for hospitalization, need for ICU admission, need for use of a ventilator, and risk of death.
  • Because your fetus may be at risk for preterm birth if you get a COVID-19 infection during pregnancy.
  • Because COVID-19 is dangerous to the people around you.

What should you consider when deciding on whether to receive a COVID-19 vaccine?

  • Your risk of becoming exposed to COVID-19 infection.
  • Your risk of becoming severely ill with COVID-19 (Risk factors include pregnancy, high blood pressure, diabetes, obesity, older age).
  • The benefits of becoming vaccinated.
  • The data on safety of COVID-19 vaccines for pregnant women.

How safe are other vaccines that pregnant women routinely receive?

  • Vaccines are one of the greatest public health successes of modern times.  Several vaccines have routinely been given for decades during pregnancy and to breastfeeding women, such as TDaP for pertussis (“whooping cough”) and influenza vaccine (“the flu shot”).  These vaccines decrease the risks of severe illness and death of pregnant women and of their infants after birth if mothers receive the vaccine during pregnancy.
  • Live vaccines are generally not recommended during pregnancy.

What are the Pros and Cons of vaccination?


  • Vaccination can help you avoid becoming infected with Covid. 
  • Vaccination can help you avoid serious complications from Covid if you do become infected despite being vaccinated.
  • You may be able to do things you had to stop doing because of the pandemic.
  • You will give your baby antibodies to Covid that may protect him or her after birth.
  • You are less likely to transmit Covid to people around you.


  • There are side effects with vaccination:  most of them are mild and short-term; but there are some that are serious, though serious side effects are very rare.

What side effects with vaccination should you be aware of

  • Side effects with vaccination during pregnancy are similar to those in non-pregnant individuals.
  • Of note, a recent analysis of 35,691 v-safe participants who were pregnant showed that pregnant women were more likely to have injection site pain, but less likely to have fever, chills, muscle aches, and headache.
  • Pfizer and Moderna are mRNA (messenger RNA) vaccines and can cause mild flu-like illness symptoms, such as injection site soreness, fatigue, chills, muscle pain, joint pain, and headache.  Fever occurs in <16% of women after their 2nd shot, and usually resolves within 3 days.
  • The J&J vaccine can cause mild and transient side effects, usually lasting 1-2 days, such as muscle pain, headache, fatigue, and injection site soreness.  9% of individuals experience fever.
  • If you develop a fever after vaccination, Tylenol should be used.  Fever for any reason in pregnancy is associated with some adverse pregnancy outcomes.  It is safe to use Tylenol in pregnancy and does not impact the antibody response to the vaccine.

Serious side effects with vaccination:

Though very rare, the following side effects are significant and are associated with vaccination:

  • Anaphylaxis is a severe allergic response to the vaccine or any of its components.  This occurs in less than 1% of the recipients of Pfizer, Moderna, or J&J.
  • CVST stands for Cerebral Venous Sinus Thrombosis; this is a condition where blood clots form in various places in the body (such as the brain, the abdomen, or the legs) along with low levels of platelets (the component of the blood that, ironically, helps people to form clots).  Symptoms include severe headache, visual changes, abdominal pain, nausea and vomiting, back pain, shortness of breath, and leg swelling, etc.  The condition occurs 6-14 days after vaccination with the J&J vaccine.  6 cases have been described in the U.S. (none of them were pregnant), and the rate of occurrence is 7 per million doses of J&J given (which is less than the risk of a person being struck by lightning).  Though pregnant and recently delivered women ARE at increased risks of blood clots, these blood clots occur through a different mechanism than CVST, and pregnant or postpartum women are not thought to be at increased risk of CVST if they get the J&J vaccine.

The 3 COVID-19 vaccines approved for EUA in the United States:

  • All 3 are highly effective.
  • They are not live virus vaccines and cannot cause COVID-19 infection.
  • The clinical trials on the safety and efficacy of the vaccines met the same high standards as with a typical vaccine approval process; despite the rapid development of the COVID-19 vaccines, safety standards were not relaxed, in fact, additional safety monitoring systems have been used to track and monitor these vaccines. 
  • Safety data on their use in pregnancy do not indicate any safety concerns for mothers or their babies (over 100,000 pregnancies were reported to the CDC’s v-safe program as of April of 2021 with no evidence of any serious safety concerns).  For example, outcomes for vaccinated pregnant women and unvaccinated pregnant women were NO DIFFERENT for the following conditions:  miscarriage, stillbirth, gestational diabetes, pre-eclampsia, growth restriction, pre-term birth, and birth defects.

Pfizer and Moderna

  • These are mRNA vaccines.  They consist of mRNA encapsulated by a lipid nanoparticle.  They use the host cell’s machinery to make the coronavirus spike protein.  The spike protein then stimulates the host’s immune cells to make antibodies against COVID-19.
  • These are not live virus vaccines.
  • They cannot cause Covid infection.
  • They do not use an adjuvant to enhance vaccine efficacy.
  • They do not enter the nucleus of the host cell and cannot change the DNA (the genetic material) of the host cell.
  • They are 94-95% effective in preventing laboratory-confirmed COVID-19 illness.

J&J vaccine

  • The J&J vaccine is made from recombinant, replication-incompetent human adenovirus type 26 vector which encodes the SARS-CoV2 spike protein.
  • It is not a live virus vaccine.
  • It cannot cause Covid infection.
  • The adenovirus vector cannot replicate after administration.
  • The vaccine is rapidly cleared from tissues after injection.
  • It cannot alter the DNA (the genetic material) of the host cell.
  • It contains no preservatives.
  • Other adenovirus vector vaccines have been tested in pregnant women, including vaccines against HIV and Ebola, and have been found to be safe.
  • It is 66.9% effective in preventing severe Covid illness after one dose.
  • It is 93.1% effective in preventing hospitalization due to Covid illness.

Which vaccine should you choose?

According to the Advisory Committee on Immunization Practices, any of the 3 vaccines approved for EUA in the U.S. are acceptable for use in pregnant or breastfeeding women.  There is no preference for one vaccine over another.

Timing of vaccination:

  • Any trimester of pregnancy is appropriate for vaccination.
  • You may receive Rhogam at the regular times during and after pregnancy, regardless of when you get your Covid vaccine.
  • You should not stop aspirin or other anticoagulants used during pregnancy or breastfeeding because of getting a Covid vaccine.
  • If you’ve already had Covid, data from trials show that Covid vaccines can be safely given to people with prior Covid infections.  The CDC recommends waiting until you have recovered from the acute illness and have met the criteria to discontinue isolation.  There is no recommended minimum interval between infection and vaccination; two factors to consider are that the risk of infection is low in the months after the initial infection but that this risk increases over time due to waning immunity. 

If you choose to vaccinate:

  • This is your choice.
  • You may be able to have more freedom to do the things you had to stop doing because of the pandemic.
  • Your baby may benefit from your antibodies.

If you choose NOT to vaccinate:

  • This is your choice.
  • You should continue to observe other safety measures to protect yourself and others, such as wearing a mask, social distancing, and avoiding crowds.
  • You can still get the vaccine after you deliver/when you are breastfeeding.

Other things to know:

  • Women who are vaccinated during pregnancy pass on antibodies to their babies during pregnancy.
  • Covid vaccines can be given during breastfeeding, and antibodies are present in the breastmilk.
  • Covid vaccines are not associated with infertility.  Claims linking vaccines to infertility have been scientifically disproven.  The American College of Obstetrics and Gynecology recommends vaccination of all eligible women considering future pregnancy.
  • You should not delay pregnancy in order to get your Covid vaccine.  It is also ok to get your 2nd shot of an mRNA vaccine even if you become pregnant after the first shot.
  • If you get a mRNA vaccine, you should use the same vaccine for your second shot.
  • You should not stop breastfeeding in order to be vaccinated.




  • The American College of Obstetricians and Gynecologists Website:  Practice Advisory:  “Vaccinating Pregnant and Lactating Patients Against COVID-19”.  December 2020 (updated April 28, 2021).
  • Centers for Disease Control and Prevention Website:  “Information about COVID-19 Vaccines for People who are Pregnant or Breastfeeding.  Updated 4/28/2021.
  • “SARS-CoV-2 Specific Antibodies in Breast Milk After COVID-19 Vaccination of Breastfeeding Women” in JAMA. 2021; 325(19):2013-2014.
  • “Association of Maternal Perinatal SARS-CoV-2 Infection With Neonatal Outcomes During the COVID-19 Pandemic in Massachusetts”.  JAMA Netw Open. 2021;4(4):e217523.
  • “Maternal and Neonatal Morbidity and Mortality Among Pregnant Women With and Without COVID-19 Infection  The INTERCOVID Multinational Cohort Study.  JAMA Pediatr.  Published online April 22, 2021. doi:10.1001/jamapediatrics.2021.1050.






Written by Dr. Kathleen Watt

Dr. Watt has been with Women's Health Care Associates (a division of OB/GYN Affiliates) since 2001, after completing her residency at Denver's Exempla/St. Joseph Hospital.  She earned her medical degree from the University of Colorado Health Sciences Center in 1997.  She also has a Master of Science degree in Biological Sciences from the University of Denver and earned her Bachelor of Arts in German Language and Literature from Northwestern University in Evanston, Illinois.

She is board certified by the American Board of Obstetrics and Gynecology and is a Fellow of the American College of Obstetricians and Gynecologists.  She is a member of the Alpha Omega Alpha Medical Honor Society.  Her medical areas of interest include health maintenance, disease prevention, minimally invasive gynecologic surgery, and evidence-based medicine.

Dr. Watt and her husband have two children and a new dog "Hobbes." In her spare time, she enjoys mogul skiing, reading, exercise, and cooking. She is also fluent in German.

To schedule an appointment with Dr. Watt, visit



Category: Pregnancy