Covid-19 Vaccination and Pregnant Women


What’s a pregnant lady to do?? She wants the very best for her unborn baby. Yet, pregnant women are generally not included in pharmaceutical trials for new vaccines and new medications.  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 the 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 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 effect or complications that people experience in the real world.  This system is co-managed by the CDC and FDA and accepts reports by 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 an 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.  As of December 2021, with the surge of the Omicron variant, the CDC has recommended that all individuals should seek the Moderna or Pfizer vaccine, unless they have an allergy to PEG. Individuals with specific medical concerns can seek medical guidance or speak with Dr. Moomjy 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.

Concerns about the impact of the vaccine on fertility have been fueled by social media but based on individual opinions and not upon scientific evidence.  Social media is prone to misinformation.  Scientific reports have many reviews by experts in medicine, prior to acceptance for publication. There is scientific evidence from animal studies; and from the assessment of follicular (ovarian) fluid and semen from IVF patients; and from the microscopic assessment of placentas at delivery, that have all shown that there are no differences between vaccinated and unvaccinated individuals.

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.  Recent reports from the U.K. revealed that nearly 20% of the most critically ill patients with COVID-19 in England were unvaccinated pregnant individuals. It has long been known that viral infections can be more severe in pregnant individuals as the immune system is altered to permit embryo implantation and fetal growth.  Alternatively, vaccination during pregnancy has been associated with transfer of protective antibodies through the placenta to the fetus, providing benefit to the fetus.

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.



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.

Girardi, G, Bremer, AA, “Scientific Evidence Supporting Coronavirus Diseases 2019 (COVID-19) Vaccine Efficacy and Safety in People Planning to Conceive or Who are Pregnant and Lactating,” Obstetrics & Gynecology, January 2022:139 (1), 3-8.

“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.

You Might Also Enjoy...



These are 2 pictures of the endometrium, or uterine lining, as seen under a microscope with special stains to highlight the cells, each with a bright purple nucleus. These pictures are substantially different: the one on the left has 2 simple round...

Gestational Surrogacy is Legal in NYS!

February 2021 saw a landmark event occur in NYS when commercial surrogacy became legal. Previously, NYS was one of only 3 states in which this form of family building had been illegal.


This is a very common hormonal condition that affects 3-8% of the female population. As you may already know, PCOS stands for Polycystic Ovarian Syndrome; but it is a misnomer and it is time to change that!

Lessons From COVID-19

The Covid-19 Pandemic has affected every citizen of this world. It has been a highly contagious and highly virulent virus that has a mortality rate up to 10 times greater than the typical flu! In this post, we aim to highlight lessons we can learn from Cov

HSG (Hysterosalpingogram)

As a Reproductive Endocrinologist, the information is priceless; as the patient, the procedure is a hassle, but certainly valuable when establishing the best long-term plan for conceiving. The tubes normally do not reveal themselves on a pelvic ultrasound.