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The COVID-19 mRNA vaccine and pregnant or breastfeeding women Part 1

Updated: Apr 11, 2023

The mRNA vaccines from Pfizer/BioNTech and Moderna which are currently being administered in the USA, under emergency authorization, were NOT studied in pregnant and breastfeeding [lactating] women. What does this mean? Without studying this group of the population there is no direct safety information that can be shared, at this time, about the effect [short and long term] on children who are exposed to the vaccine in the womb or through breast milk.

These women were not studied because they are considered a special population for which human research authorities have very strict rules put in place for the safety of the exposed unborn and born child. A colleague once told me that Obstetrics was still on the frontier of medicine. There is still so much understanding to uncover in this field of medicine. See the following link to an article on the Pfizer & BioNTech vaccine trial: Safety and Efficacy of the BNT162b2 mRNA Covid-19 Vaccine | NEJM See the following link to an article on the Moderna vaccine trial: An mRNA Vaccine against SARS-CoV-2 — Preliminary Report | NEJM

The American College of Obstetricians and Gynecologists and the Society of Maternal-Fetal Medicine published statements advocating for ACCESS to the vaccine for pregnant and breastfeeding mothers. These statements support the woman’s right to CHOOSE whether to take this vaccine. These statements advocate against authorities DENYING women access.

The statements DO NOT write that the panel RECOMMENDS the vaccine to this special group nor that they vouch for the safety of the vaccine concerning the exposed unborn and born children of pregnant and/or breastfeeding women who receive this vaccine. Words matter! Please read these statements very closely.

The Academy of Breastfeeding Medicine published a statement regarding COVID-19 vaccination in lactating persons in the United States. The statement includes a summary of how the vaccine causes an immune response. The critical reader will notice that there are no references included in this statement. References are used by the medical community to allow anyone to read scientific information for themselves by finding the associated scientific publication upon which support for a statement was derived. There are NO included references next to the phrases about ‘likely’, plausible’ or ‘biology’.

Without references, the reader cannot learn how the writer came to the understanding that they are trying to convey. In science, facts matter. Look for references and feel free to read them to see if you agree with the message associated with the reference. And if there is no reference, consider what you are reading an opinion, rather than a conclusion from rigorous investigation. Use the link provided to see the full statement about the mRNA COVID-19 vaccines using the following link: ABM Statement: Considerations for COVID-19 Vaccination in Lactation (

Since the mRNA COVD-19 vaccines were NOT studied in pregnant or breastfeeding, vaccine registries may be the first way that we get safety information about this special group. Registries allow groups to track safety information and are often how we get safety data on medications used by pregnant and breastfeeding women. When an individual enrolls in a registry they volunteer to answer questions or have information tracked [about their pregnancy or their children’s pediatric outcomes]. Pregnant and breastfeeding healthcare workers will be among the first in this special group to decide whether or not to receive the COVID-19 vaccine. At the current pace of vaccination, it will take some time to vaccinate that majority. If these healthcare mothers who CHOOSE to receive the vaccine enroll in registries then they can help us learn so much for the benefit of the greater community of mothers.

As an OBGYN, I have asked my patients that were taking a medication without much safety data to enroll in a medication registry. Now the table is turned and patients should ask their providers and other members of the healthcare workforce to enroll in a registry. The following is an available COVID-19 registry for pregnant and breastfeeding individuals through the University of Washington COVID-19 Vaccine in Pregnancy and Lactation: Registry to Explore Immunization Practices, Outcomes and Quality Improvement Initiatives (

This article was written by: Kia Lannaman, MD

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