COVID Vaccines with Pregnant or Breastfeeding Moms

Below is an opinion based article and not meant to be medical advice. Please discuss any medical decisions while pregnant with your personal physician.

In the pediatric realm we get many questions involving pregnant or breastfeeding moms and what medications are considered ok during those times. Many moms receive their flu booster or Tdap during pregnancy and MMR while breastfeeding without any complications or risks. The COVID vaccines have become another hot topic on if moms who are pregnant or breastfeeding should get it or not. Although there are not enough set studies out there to refer to based on this question, we can use what we already know about how these vaccines work and how the human body interacts with them to make educated decisions while waiting for these studies to reach completion.

STOP All of the Rumors…Seriously

Can we just squash all the rumors out there that the vaccines will cause birth defects, alter genes, or lead to infertility? This is completely false and has no scientific backing whatsoever.

I literally have no idea where the birth defect argument came from. To be honest, for a birth defect to occur it would have probably had to happen during the first trimester. That would have been up to 3 months into pregnancy. Meaning if someone delivered a baby post vaccine, they would have had to have received the vaccine AT LEAST 6 months ago. The vaccines have only been available for emergency use for the last 3 months or so. The time tables don’t add up.

As for the infertility comment, this was based off the assumption that the antibody response to the spike protein in SARS-CoV-2 would be a similar response to the Syncytin-1 protein utilized in placental insertion in the uterus during pregnancy.

Why was this assumed? Because the spike protein and Syncytin-1 share a set of genetic coding that is similar. How similar? A total of about 4 amino acids in a row out of over 500 amino acids in the chain. This is NOT significant enough to create an autoimmunity within the uterus. If this were true, we would also see women who had COVID becoming infertile. We are not seeing this.

Pregnancy and the Vaccine

The initial trials of the vaccines did not include pregnant women, as most trials typically do not in their early stages. Do I have set data to go off of to discuss this in great scientific detail? No. However, some women in the trials early on later found out they were pregnant or became pregnant during the trial (because let’s face it, what else were we supposed to do while stuck at home?). Although those women were removed from the trial, the study investigators continued to follow their health and that of the baby. No increased risks were found up to this point related to the vaccine including miscarriages, spontaneous abortions, birth defects, or other complications.

What we do know from the data is that pregnant women who become sick with COVID have a higher chance for preterm labor. However, this is true for many illnesses during pregnancy. As a woman becomes pregnant, their blood volume increases. This also leads to a lower immune response during pregnancy, making moms have a higher likelihood of getting sick while pregnant. This increase in stress on the mom and the unborn fetus can lead to triggers that include early labor. Thus, protecting the mom from potential infection or complications from infection by means of a vaccine is beneficial to both mom and baby.

You may have also heard of recent findings of antibodies against SARS-CoV-2 found in newborn babies after maternal vaccination during the 3rd trimester. This is incredible news. We still do not have data on how long these antibodies last, but we do know most babies are protected for the first 3 months of life from maternal antibodies until the baby’s own immune system takes over.

COVID Vaccine and Breastfeeding

This is another question that gets asked to our office frequently – is it ok for moms to breastfeed after getting the vaccine?  Absolutely.  The mRNA vaccines break down in the muscle tissue locally and the mRNA is unable to spread systemically throughout the blood stream.  The Johnson & Johnson vaccine (adenovirus vector) is a slightly similar build to other virus-vector vaccines which we know can be safely used during breastfeeding as well.  

There are studies currently going on assessing if maternal antibodies for COVID can be found in breast milk. Although it is early, one study in pre-print (not yet peer-reviewed) from Portland, Oregon, followed 6 moms who elected to get the vaccine while breast feeding. Maternal antibodies were tested in the breast milk before, during, and after the vaccine. None of the moms had a previously known exposure to COVID prior to the study.

What they found was 7 days after the first vaccine (either Moderna or Pfizer) there was an increase in IgG and IgA antibodies toward SARS-CoV-2 in the breast milk. These levels continued to increase after the second dose and were still present 14 days after that second dose. No further testing of the breast milk was done after that 14 days post 2nd dose.

In These Breast Milk Samples, There Were More IgG Antibodies Present When Compared to IgA. What Does That Mean?

IgG antibodies are the antibodies created in your body and seen within the blood stream, mainly protecting from systemic spread and significant illness. These are the typical antibodies you see formed after receiving a vaccine. This means that the baby may be protected from significant infection from COVID when absorbing these antibodies. Good job mom!

IgA antibodies are the antibodies that live in our mucosal regions (nose, throat) as well as the gut (stomach and intestines). These antibodies may help protect from initial infection and ease of spreading the virus (ie the virus can not replicate in the nasal passages). As babies are not great at creating respiratory droplets and spreading illness, this decrease in IgA volume vs IgG shouldn’t be an issue, and those IgG antibodies should ultimately protect the baby from significant illness.


Again, I can’t tell you at this point in time (March 30, 2021) that I have a concrete study or data to say “Yes, we have studies involving pregnancy and breast feeding with the vaccines and they are safe!” However, from the few women who started in the vaccine trials as well as what we are seeing in the community with babies born shortly after mom being vaccinated, I am very comfortable with recommending the vaccines for both pregnant moms and breastfeeding moms to get vaccinated provided they feel comfortable doing so. I recommend all patients to discuss this with their specific physician and find a plan that makes sense.

Stay Healthy

Stay Safe

Imperfect Dad, MD

Leave a Reply

Fill in your details below or click an icon to log in: Logo

You are commenting using your account. Log Out /  Change )

Facebook photo

You are commenting using your Facebook account. Log Out /  Change )

Connecting to %s