How Your Placenta and Your Breastmilk Can Protect Your Baby Against COVID-19


Hey hey hey! Wednesday!

I hope your week is going great. My two year old turned on my heat sometime today and it took me until 9pm to figure out why my house was 75 degrees….seriously. Once they find the step stool, there is no height they will not climb or things they will not experiment with. I can just see him standing there at the thermostat thinking…”I wonder what this switch does?”

Onto antibodies!

There has been a theme in my conversations this week and that has been the maternal transfer of antibodies. I also like to think of this as the superpower that all women have.

There are two antibody transfers that happen during pregnancy and birth. The first happens in the third trimester of pregnancy. The second happens during breastfeeding.

During pregnancy, the placenta transfers antibodies to the baby via the placenta (the super organ!). For example, if you had chickenpox as a child, your placenta will transfer IgG antibodies (protection) to your baby for chickenpox. Since this transfer happens naturally, this is called “passive immunity.”

The same superpower happens again with breastfeeding. Antibodies continue to transfer from the mother to the baby during breastfeeding to infections the mother has had in the past AND to infections she gets while breastfeeding.

I like to give this example to patients. When my daughter was a newborn (about 10 weeks old), I was really sick. I was coughing and coughing and coughing and my heart rate was elevated at the rate of 120 beats per minute for about a week. The provider diagnosed a viral URI and I was so sure that my daughter was going to get sick since she was so little and I was so sick.

I was wrong. I breastfeed her every few hours and coughed all over her night and day. She was completely fine and never even had a cough. That was because as my body was making efforts to fight the infection, my breasts were pumping antibodies into the breast milk that she was drinking.

If you’re wondering how it works, this video is a nice review.

Also, for the record, I love the placenta. I don’t think the organ gets enough credit for the amazing work it does.

Onto antibodies…

If you’re pregnant, or you remember getting a recommendation to get a TDaP or whooping cough vaccine when you were pregnant, the antibody transfer is the reason providers recommend this vaccine during 27-36 weeks of pregnancy.

You can get a TDaP vaccine if you step on a nail at 16 weeks pregnant, but you won’t transfer a lot of passive immunity to the baby like you do after you get a TDaP vaccine in the third trimester!

It’s the same with COVID-19. In rounding on my postpartum couplets this week, a lot of women chose not to get the vaccine while they were pregnant. I spent a lot of time reviewing the vaccine and the benefits of the antibody transfer to women that are choosing to breastfeed (and also for women to protect themselves if they haven’t had the vaccine).

Before we go on, choosing to get the vaccine is a personal decision. Let’s just lay that on the table. There’s no judgement here either way.

But I want to highlight a couple things that are particular to pregnant and nursing women that keep coming up in my postpartum rounding.

Not every child has a mother that is pregnant or nursing.

My two year old is an example of this. I can’t give him antibodies to COVID-19 unless I pour some of my pumped breast milk into his oatmeal. And there’s not a vaccine to protect him either right now. But I can offer that protection to my eight month old baby because I am nursing. This is why I chose to get the vaccine in January 2021 when he was a newborn to pass COVID-19 antibodies to him as protection. Pregnant women are the same. Because you are pregnant, you have an opportunity to offer your child some protection against a virus.

Breastmilk continues to offer protection every day you breastfeed.

I don’t have enough words (or time) to talk about why people call breastmilk liquid gold. Or how wonderful breastmilk is for your baby. But it really is liquid gold. And like the variants of the COVID-19 virus, it’s likely that your body is able to produce different antibodies for each variant.

Breastfeeding offers long term immunity to your baby. COVID-19 vaccines are not available for newborns and children and it’s unknown what those offerings will look like in the future. Will this be a recommended vaccine like the annual flu vaccine? Will it be a required vaccine for college? All of those are unknowns. Until then, breastfeeding offers some long lasting immunity.

I also have to share this an excellent article shared by a colleague of mine on the front lines. It’s absolutely worth the read and the sharing.

Liquid Gold: How Breast Milk Could Pass Along COVID-19 Immunity

It’s also important to mention that there is probably a difference between the antibody protection you transfer if you had a COVID-19 infection and if you received the vaccines. I only mention this because if you had COVID-19 in 2020, and you have a baby in 2021, you will likely transfer some antibodies to the baby through the passive immunity we talked about above, but the antibody response is likely greater immediately after the vaccine as well. Just a thought for those that have had COVID-19 and wonder if the vaccine is beneficial for their baby.

The rates of COVID-19 infection in children are low but children can become infected and they can pass the virus to other people or other family members.

If you’re curious about the rates in children, the CDC updated their Science Brief in July 2021. It’s a nice summary of the rates in children and the transmission amongst small children to older children. The article also points out a very important point regarding children and the pandemic – everything was shut down in 2020 for kids (schools, programs, childcare…). So, when looking at transmission rates in kids, we have to remember they weren’t doing their usual routines in most households for the past year to year and a half. I think this is worth remembering and reviewing.

The vaccine is recommended for pregnant and breastfeeding women.


And the data is supporting that the vaccines are safe for these populations. The largest trial to date produced a preliminary report in the New England Journal of Medicine last month. The trial looked at the Moderna and the Pfizer vaccines (not Johnson & Johnson). The trial examined 35,000 pregnant women and no safety signals (a fancy way to say concerns) were noted in their evaluation of the data. This is a good start to following pregnant woman who have received the vaccine. If you guys remember, one of the biggest concerns with the vaccine was the initial trials didn’t include pregnant women – although some women became pregnant while they were in the trials.

When studies like this publish preliminary findings they shouldn’t change practice but they also shouldn’t be ignored.

Much more research is needed to study the vaccines long term. But that data only comes with time. But a trial like this offers a little more information specific to pregnant women instead of trying to apply trials without pregnant women to pregnant woman (clear as mud?).

Remember, what you choose to do is your choice. Be informed. Keep up with the science.

Also, if anyone has a video about antibody transfer that you can find, will you please send it to me? When you search “placental transfer of antibodies” in google, all the results have to do with COVID-19. Seriously.

The picture at the top of the post is the closest I could find…

One last shout out to this conversation tool for providers. It’s worth the read for everyone. I think it’s a nice overview and allows for questions divided by the main concerns or questions with the vaccine!


Happy hump day!


1 year ago on the blog…Friday Five (#23)

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