Covid-19 Vaccination and Pregnant Women

Waiting for reliable information on safety and efficacy can feel like an eternity, yet the baby has a due date!

As pregnant women were not included in Phase 3 Covid Vaccination trials of Pfizer, Moderna, or J&J, patients and physicians have had to make this important decision using only pharmacology information and surveillance reports. As this pandemic evolves, information evolves, and guidelines may evolve and change for all preventative measures.

The Covid-19 Vaccine is the first to apply mRNA technology (Pfizer-BioNTech and Moderna). However, the science of mRNA dates back to the 1960s and 1970s with the production of proteins by mRNA in the lab and the discovery that lipids could protect the mRNA and deliver it into cells. The “m” stands for a messenger; a limited code that directs the cell to make certain proteins. It cannot access the nucleus nor change the DNA of a cell; it is only the messenger. For the Covid vaccine, the mRNA is the code for the spike protein which stimulates the body to make antibodies against the spike protein. These antibodies act like a blockade (or Bouncer) preventing Covid from entering and causing significant infection or disease. The J&J, Janssen, vaccine is composed of an inactive virus that encodes the spike protein to also stimulate the production of spike protein antibodies.

The VAERS is a government-sponsored Vaccine Adverse Event Reporting System, that has provided much information about potential side effects or complications that people experience in the real world. This system is co-managed by the CDC and FDA and accepts reports from anyone, including patients, family members, healthcare providers, and vaccine manufacturers. It is up to the FDA and CDC to review the data and decide if further investigation or action is needed. The data is also available to the public for analysis. As of July 2021, there were more than 135,000 pregnant women registered in this database, Reassuringly, there were no increased risks of pregnancy or newborn complications compared with pregnancy data prior to the pandemic.

We also rely on Cohort studies tracking pregnant women who took the vaccine in comparison to control groups to better understand the risks and benefits of Covid vaccination of pregnant women. A recent publication from Israel, (Goldshtein, et al) tracked 15,060 pregnant women who took the vaccine early in the pandemic and found that there was a marked reduction of Covid infection among the vaccinated pregnant women with overall estimated effectiveness of 78% in the prevention of the disease. They did not detect any notable differences between vaccinated and unvaccinated pregnant women in regards to pregnancy complications. In another cohort study, Dr. Kharbanda, et al, analyzed a Vaccine Safety Datalink between the CDC and 8 major healthcare systems in the Midwest and the West to track pregnancy outcomes for more than 105, 000 pregnancies to determine if there was any association between receipt of vaccine and subsequent miscarriage. They reported that the miscarriage rate was identical between the group of women who had been vaccinated in pregnancy compared to the group of women who had not been vaccinated in pregnancy. This is very reassuring news for all of us.

Potential side effects may include injection-site pain, fatigue, chills, headache, muscle and joint pain, fever, and diarrhea. Pregnant women should take acetaminophen for any fever or chills related to vaccination. Anaphylaxis (severe allergic reaction) is rare; occurring in 11 of 1 million vaccinated people. People with a known allergy to polyethylene glycol (PEG) should seek the J&J/Janssen vaccine which has a lower risk of this allergic reaction. There is a rare risk of TTS, a thrombotic or clotting disease, with the J&J/Janssen vaccine. Currently under study is whether Guillain-Barre syndrome is slightly elevated with the Janssen vaccine. Individuals with specific medical concerns can seek medical guidance or speak with Dr. Moomjy for the selection of a specific vaccine, and to help make this important decision. The risks of side effects should always be compared to the risks of this disease which include respiratory failure, multisystem organ failure, long-term cognitive disability, and chronic fatigue syndrome, and death.

When considering vaccination in pregnancy it is important to understand the realities of Covid infection in pregnancy. Pregnant patients experience more severe illness than nonpregnant people; they have an increased risk of ICU admission, need for ventilatory support, and subsequent death. Pregnant patients with obesity and diabetes have an even higher risk of severe illness. All of which can lead to prematurity and complications of prematurity. While pregnant women may be super cautious to avoid exposure, this is a pandemic with a virus that has mutated to become even more infectious.

The American College of Obstetrics and Gynecology (ACOG) recommends that pregnant individuals be vaccinated against COVID-19. ACOG cites that there is currently no evidence for adverse maternal or fetal effects from vaccination during pregnancy and that there is “a growing body of data demonstrating safety” of these vaccines. ACOG: Covid Vaccination in Pregnancy



Picture by Alice Neel

Dolgin, E., “The Tangled History of mRNA Vaccines,”, Sept 14, 2021,

Goldshtein, I, Nevo, D., et al, “ Association Between BNT162b2 Vaccination and Incidence of SARS-CoV-2 Infection in Pregnant Women”, JAMA, 2021; 326 (8): 728-735.

“FDA Authorizes Pfizer-BioNTech COVID-19 Vaccine”, The Medical Letter, Issue 1615, January 11, 2021.

Kharbanda, E.O, et al, “Spontaneous Abortion Following COVID-19 Vaccination during Pregnancy” JAMA, online Sept 8, 2021/jama.2021.15494

“COVID-19 Vaccination Considerations for Obstetric-Gynecologic Care, Practice Advisory” Dec 2020, Updated July 30, 2021.

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