Everything you need to know about vaccines and pregnancy

Everything you need to know about vaccines and pregnancy

Which vaccines are recommended during pregnancy? Why? And most importantly – when?

This is a very important topic that is indirectly related to pediatrics.
And if we’re already here, I’ll tell you a secret. In the past my dream was to open up a clinic for infectious diseases in pregnancy, with an emphasis on vaccines during pregnancy. I even went as far as to think about the possibility of granting couples an appointment to the clinic as a wedding gift…
I tell you all of this to emphasize that ideally, and if permittable, the thought process about diseases and vaccines in pregnancy should be held prior to becoming pregnant. In addition, one should not only think about the mother’s vaccine status, but also try and maximize the father’s vaccine status.
To summarize, I would like to state that the best-case scenario would be if a couple planning for a child would see their family physician half a year prior to when they plan to become pregnant, bring with them both their vaccine records, and put together a joint vaccine program.

Please note, this is not a summary of all the potential infectious diseases in pregnancy, but only those that can be prevented through vaccines. I advise you to extend the span of your reading so that you cover the prevention of two additional important diseases in pregnancy – cytomegalovirus infection (summarized in the link here) and toxoplasma (in the link here).

Some basic points that are important for you to understand:

What are the reasons one should get vaccinated during pregnancy?

There are several reasons:
Direct protection of the pregnant mother – pregnancy is a type of medical condition that puts the mother at a higher risk of infectious diseases and different complications. Some infectious diseases are more severe in pregnancy and so our desire is to protect the pregnant woman from as many infectious diseases as possible.

Direct protection of the fetus – the pregnant mother transfers antibodies against many different infectious diseases to her child, mainly during the third trimester but afterwards when breastfeeding. For example: vaccinating a pregnant woman against pertussis will cause her to develop antibodies against the disease. These antibodies will be transferred to the fetus passively and will protect it against getting infected for a certain period of time.

Protection against congenital syndromes – vaccines exist against a number of different infectious diseases that may occur during pregnancy, where a maternal infection with any one of these could lead to unpleasant congenital syndromes in the fetus. Examples: rubella and varicella.

Prevention of premature delivery – many of the infectious diseases that can occur during pregnancy, in fact, all febrile diseases occurring during pregnancy, have been associated with premature delivery. And if we can prevent that, then all the better.

Are all vaccines safe during pregnancy?

No. One should avoid giving a pregnant woman live-attenuated vaccines. Therefore, the idea is to give vaccines in advance, before a woman becomes pregnant.

Which diseases have vaccines that all pregnant women should be vaccinated with?
See more details about each one of these diseases below.
Hepatitis B.
Chickenpox (varicella).
Rubella (and measles and mumps too).

Hepatitis B vaccine during pregnancy

This is the only disease that has a vaccine, for which almost universal screening during pregnancy is carried out in most countries. Hepatitis B vaccination has been available since the early 1990s, and is part of the childhood routine vaccination schedule in most countries. However, there are still some people who haven’t been vaccinated and others who caught the infection and have become chronic carriers but aren’t aware of this. Therefore, any woman without vaccine records showing that she has received three doses of Hepatitis B or whose blood results fail to show antibodies at a sufficiently protective level must start a new series of vaccinations. It is preferable to get vaccinated prior to becoming pregnant, but it is also safe to receive these vaccinations during pregnancy.

Pertussis (and tetanus and diphtheria while we’re at it)

Getting pertussis during pregnancy is a horrible experience. I have seen, in my very own eyes, women who have had their ribs broken from their strong cough. So, it is really worthwhile protecting women from this infection.
And just as important – the goal of vaccinating women during pregnancy is to protect their infants from the infection. This is because getting infected with pertussis under the age of 6 months is in potential a very severe disease. In most countries in the world, infants receive their first pertussis vaccine dose at 2 months (and then at 4 months, 6 months and 1 year), but the vast majority of them are unable to develop antibodies at a rate that is quick enough to provide them protection from the infection in the first half year of life. Research has shown that giving the vaccine in the third trimester decreases the prevalence of infection in infants after birth. How? Both because their mother can’t get infected and transfer the disease to them and also because of the passive transfer of antibodies that I have mentioned above.
In most countries around the world, pertussis vaccine is recommended for pregnant women, between gestational weeks 27 and 36, during each pregnancy, regardless of the number of years that have passed since the previous pregnancy. I suggest receiving the vaccine early on, around gestational week 27, in order to maximize the amount of antibodies that get transferred to the baby and also to protect the mother during labour.
How are tetanus and diphtheria related to pertussis? The vaccine that is generally given contains vaccines against tetanus, diphtheria and pertussis combined. There is no harm in receiving a tetanus vaccine every few years but there is a disadvantage to it. What is it? The site of injection on the arm hurts more with each vaccine. Not the end of the world, I must say.

Chickenpox (varicella)

Most of us had chickenpox in our childhood. But the prevalence of the disease has been slowly dropping, and the current generation of children has received the chickenpox vaccine and hasn’t had the disease. Here and there, there are still some adults who never had chickenpox and may be prone to infection during pregnancy.
Chickenpox manifests as a generally more severe infection when one gets it at an older age, in comparison to people at a younger age and includes respiratory involvement. In addition, infection at the early stages of pregnancy can lead to a congenital syndrome in the fetus. Since the chickenpox vaccine cannot be given during pregnancy (as it is a attenuated live virus vaccine), I advise all women (and men) who do not remember whether they have ever had chickenpox or whether they have received two vaccine doses, to take an antibody test. If they do not have antibodies, getting the vaccine (one or two doses, as needed) is recommended when planning a pregnancy. Notice below how women who need to get the chickenpox vaccine and the rubella vaccine can get both in the same injection (referred to as the MMRV vaccine).
So, as I explained above, the vaccine against chickenpox is an attenuated, live virus vaccine that cannot be administered during pregnancy. Ideally, it should be given about three months before a woman gets pregnant. Remember that some women need two doses, each of which need to be given at least one month apart. In short, we’re back to square one – plan in advance!

Rubella (and measles and mumps while we’re at it)

Rubella (do not confuse with Roseola) is a mild childhood disease. However, getting rubella during pregnancy can detrimentally affect the fetus and lead to an unpleasant congenital syndrome. Therefore, all women who are planning to become pregnant should make sure they are vaccinated against Rubella since this vaccine is an attenuated, live virus vaccine that cannot be given to women during pregnancy. Another reason to plan the pregnancy in advance.

When is a woman considered fully vaccinated against Rubella?

A woman who has vaccine records of having received two doses of Rubella, after the age of one, where the doses are at least four weeks apart.
A woman who has been tested for antibodies against Rubella and whose results indicate that she is positive for antibodies (in my country it is at least 31 International Units or more, check for your local cut-off for positive/negative results).
There is no need for a third dose of Rubella since a woman who has records of having received two doses is considered vaccinated.
Again, this vaccine is also a live attenuated vaccine that cannot be administered during pregnancy. So, we need to plan ahead.

Measles and mumps – these are two additional viral infections, that are absolutely unpleasant to get during pregnancy and whenever, and the only reason I mentioned them here is because the rubella vaccine will always be given in combination with these other two viral vaccines and is called the MMR vaccine (Measles, mumps and Rubella). This vaccine, as I’ve mentioned before, is an attenuated, live virus vaccine, and should be given at least three months before becoming pregnant.

Influenza vaccine during pregnancy

Okay, there’s no need to go into the general importance of this vaccine or the specific importance in pregnancy. Let’s just say that one of the known risk factors for complications from influenza is pregnancy, and all pregnant women are advised to receive the influenza vaccine during the flu season. Take into consideration that the newborn will not be able to receive the flu vaccine in the first half year of his life and so if the mother and the remaining family members are vaccinated, the risk of influenza spreading amongst the family decreases and this offers the child protection against an unpleasant disease. More data of influenza vaccine is found here.

What happens when a woman isn’t able to get vaccinated before or during pregnancy?

Notice that the time period following delivery (the first 6 weeks) is also a good opportunity for catching up on vaccines, especially when another future pregnancy is being planned.

So, how shall we summarize this post?
Pregnancy is a time period where we have little control over many different factors. But it is worthwhile stopping and planning for those few factors we do have control over.

If you’d like to read more about prevention of other diseases, that do not have vaccines, during pregnancy, I suggest you read the post about prevention of congenital Cytomegalovirus (CMV) which is super important! And the one about prevention of another important infectious disease – Toxoplasma.

Good luck!

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