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Hem Flu (influenza) vaccine during pregnancy – pros and cons

Flu (influenza) vaccine during pregnancy – pros and cons

Influenza vaccine for pregnant women

This post is also available in: Svenska

Flu vaccines are offered to all pregnant women in Sweden. In this blog, we write about why flu vaccines are offered to all pregnant women and the pros and cons of vaccinations against influenza during pregnancy.

Read more about influenza vaccines for children here. 

Pregnant women are at increased risk of severe flu

The reason why influenza vaccines are recommended to pregnant women, is that pregnant women are at increased risk of severe flu disease compared to non-pregnant women. This is particularly high for certain types of viruses, such as swine flu (A/H1H1) which spreads every year.

Pregnant women are more likely to be hospitalized and treated in intensive care for influenza compared to their non-pregnant peers.

Influenza vaccine is safe for the fetus

Influenza vaccine is safe for the fetus. There is no increased risk of miscarriage, premature birth, low birth weight fetal death or birth defects. Some studies suggest a reduced risk of both late miscarriage, fetal death and premature birth in vaccinated compared to unvaccinated pregnancies.

On the other hand, influenza (especially severe influenza that requires hospitalization) in pregnant women may actually be harmful to the development of the fetus. If pregnant women are protected from influenza, the fetus is also protected. However, there may be other attributing factors that influence the development of the fetus that coincide with a pregnant woman’s decision to vaccinate. Maybe the coincidence is that vaccinated pregnant women smoke less? In that case, it may be that vaccinated pregnant women tend to have slightly healthier pregnancies.

Why do you only give flu vaccines after week 16?

The increased risk of influenza in pregnant women is mainly seen in the third trimester. This means that we can wait until the risk of miscarriage during the 1st trimester has decreased, and routine ultrasound scans have been done. Did you know that more than 10% of all pregnancies end in miscarriage before week 12? If we were to vaccinate all pregnant women between week 6 and week 12, of the > 10,000 pregnant women with miscarriages each year many women would think that it was in connection with the vaccination. Some may coincidentally have the miscarriage on the day of vaccination. However we know for certain, based on years of experience vaccinating pregnant women, that the vaccine itself does not increase the risk of miscarriage.

Some fetuses have malformations, and this is detected during routine ultrasound in many cases. In order avoid uncertainty about whether the malformations are caused by the vaccine, people prefer to vaccinate afterwards, in 3rd trimester. However, many pregnant women in the world are vaccinated in the first trimester with the influenza vaccine, and there have been no increased risk of birth defects detected.

Importantly, pregnant women who have other risk factors for severe flu (such as chronic heart and lung diseases, diabetes, etc.) are advised to take the vaccine as soon as the influenza vaccinations are available. This is because the benefits of vaccination are so great for that group that you would like them to be protected throughout the flu season.

It also means that if you want to get vaccinated early in the season, whether you’re in Week 14 or Week 7, you can definitely do it.

Flu vaccination for pregnant women protect newborns against the flu

Because the mother is vaccinated against influenza, she will protect her newborn child against infection in two ways. One, the mother herself will be less likely to become ill once the child is born. Thus, she is less likely to transmit the disease to her child.

And two, vaccination towards the end of pregnancy will result in increased levels of antibodies in the mother during the last trimester. Antibodies are transmitted to the baby (via the placenta) and gives the child an innate protection against influenza for the first few months of life. After that the antibodies are destroyed and the child must provide its own protection.

Read more about the flu in children here. 

Disadvantages of flu vaccination for pregnant women

A disadvantage of the influenza vaccination is that the vaccines are not 100% effective. In fact, far from it. So you can get sick even if you have received a vaccine. The side effects are generally mild – redness and pain at the injection site and a slight fever for a few days.

Should you have more vaccinations while pregnant?

In Sweden there are no official recommendations on other vaccines for pregnant women. In more and more countries, however, pregnant women have started to be vaccinated against whooping cough. It is safe and effective. It protects newborn babies from whooping cough before they have received vaccines themselves. If you want to get a booster dose of the whooping cough vaccine during pregnancy in Sweden, you have to attend a vaccination agency and pay for it yourself. The booster dose also contains vaccines against diphtheria and tetanus.

Read more about whooping cough in infants here. 

Read more:

Flu (influenza) in children – symptoms and treatment

Flu (influenza) vaccine for children – side effects and to whom?

Whooping cough – symptoms, how it sounds, vaccine, test and treatment

Parenthood the Swedish way – a science-based guide to pregnancy, birth and infancy

To vaccinate or not to vaccinate? About vaccinations for babies.

How does vaccines work? How vaccines strengthen the immune system

What do vaccines contain? Is aluminium, formaldehyde or mercury present in vaccines?

Public Health Agency overview on vaccinations against influenza for pregnant women

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