Why should pregnant women get the flu shot?
Influenza is more likely to cause serious illness in pregnant women, more than in women of reproductive age who are not pregnant. Changes in the immune system, heart, and lungs during pregnancy (and for up to two weeks after delivery). Making pregnant women more likely to develop serious illness from influenza that may require a hospitalization.
The flu can also be harmful to the unborn baby. A common flu symptom is fever that can be associated with neural tube defects and other adverse outcomes for the unborn baby. The flu vaccine also helps protect the baby after birth. (The mother passes antibodies to the unborn baby during pregnancy.)
A flu vaccine is the best protection against the disease
Getting a flu shot is the first and most important measure to protect against flu. Pregnant women should get the flu shot instead of the nasal spray flu shot. Injectable flu vaccines given during pregnancy help protect both mother and baby from flu.
Vaccination has been shown to reduce the risk of an acute respiratory infection, associated with influenza in pregnant women by almost half. A 2018 study found that getting the flu shot, reduces the risk of hospitalization of pregnant women from flu by about 40 percent.
Pregnant women who get vaccinated against influenza are also helping to protect their babies, and prevent them from contracting the disease during the first months after birth.
When they are too young to be vaccinated. A list of recent studies on the benefits of influenza vaccination for pregnant women is available.
Is it safe to give the flu shot to pregnant women and their unborn babies?
Yes. Injectable flu vaccines have been given to millions of pregnant women for several years with a good safety record. There is a large body of scientific studies, supporting the safety of the flu vaccine for pregnant women and their babies. CDC continues to collect data on this topic.
Can the flu vaccine cause a miscarriage?
Several studies have shown that women who were vaccinated against influenza during pregnancy have not been at increased risk of miscarriage. One of the most important and largest studies was carried out in the CDC project, Vaccine Safety Datalink (VSD).
The recently published study spanned three influenza seasons (2012-13, 2013-14, 2014-15) to detect any increased risk of miscarriage among pregnant women who received the influenza vaccine during pregnancy.
The study showed that getting a flu shot during pregnancy did NOT increase the risk of miscarriage. This study was carried out as a follow-up to a smaller previous study.
The analysed data from the 2010-2011 and 2011-2012 influenza seasons and found an association between influenza vaccination during early pregnancy and an increased risk of miscarriage; especially among women who received a flu vaccine during the previous flu season.
However, the study had several limitations, including small sample sizes that may have given inaccurate results. This study was the only analysis that showed such an association; no other studies found an increased risk of miscarriage after influenza vaccination.
At this time, the Advisory Committee on Immunization Practices (ACIP), the American College of Obstetricians and Gynaecologists (ACOG) and the CDC continues to recommend that pregnant women get the flu vaccine during any trimester of pregnancy.
As flu poses a risk to pregnant women and this vaccine can prevent serious illness and even hospitalization of pregnant women. All pregnant women with questions about the vaccine should consult their doctor.
What side effects have pregnant women experienced after receiving the flu shot?
The most common side effects in pregnant women are the same as those in other people. They are usually mild and include these:
- Pain, redness or swelling where the injection have been given
- Fainting
- Headache
- Fever
- Muscle pains
- Sickness
- Fatigue
Side effects, if they occur, occur as soon as the injectable vaccine is given and usually last 1 to 2 days. Injectable flu vaccines rarely cause serious problems such as severe allergic reactions. No person with a severe, life-threatening allergy to any of the ingredients in the vaccine should be given the injectable vaccine.
Can pregnant women allergic to eggs be vaccinated?
Most people with an allergy to eggs can get the vaccine, but they should consider some additional safety measures. A person with a severe (life-threatening) allergy to any of the components of the vaccine, including egg protein, should not be given the injectable vaccine.
Even if they are pregnant. Pregnant women should inform the vaccine administrator if they have any severe allergies or if they have ever had a severe allergic reaction after receiving an injectable flu vaccine.
Special consideration about allergy to eggs
People allergic to eggs can receive any recommended age-appropriate approved flu vaccine (IIV, RIV4, or LAIV4). People with a history of severe egg allergy (those who have had symptoms other than hives after exposure to eggs), should receive the influenza vaccine in a medical setting and under the supervision of a healthcare provider. Who is capable of recognize and manage severe allergic reactions.
Vaccine efficacy
The effectiveness of the flu vaccine (EV) can vary from year to year. The protection provided by the influenza vaccine depends on the age and health of the person who receives it, and the similarity or match between the virus (s) in the vaccine and those in circulation.
How is the safety of influenza vaccines monitored in pregnant women?
CDC and FDA conduct current safety monitoring of vaccines approved for use in the United States.
CDC and FDA monitor influenza vaccine safety in pregnancy during each influenza season through the Vaccine Adverse Reaction Reporting System (VAERS) – an early warning system that helps CDC and FDA monitor problems that may arise after vaccination. Anyone can tell VAERS about vaccine side effects. VAERS reports generally cannot determine whether a health problem that arises after vaccination (adverse event) is a consequence of a vaccine, but these reports help determine whether further investigation is necessary.
In addition, CDC conducts research studies on the Vaccine Safety Datalink (VSD) – a collaboration between CDC and nine health care organizations that enables ongoing monitoring and proactive searches for vaccine-related data.
What studies has CDC done on the safety of the flu vaccine during pregnancy?
Several studies by the CDC and its partners support the safety of the flu vaccine for pregnant women and their babies.
- The review of reports to the Vaccine Adverse Reactions Reporting System has found no evidence to suggest that there is a relationship between pregnancy complications or adverse fatal outcomes among pregnant women and injectable influenza vaccines.
- A study using data from the VSD project from all three influenza seasons (2012-13, 2013-14, 2014-15) found that receiving the influenza vaccine during pregnancy does not increase the risk of miscarriage. A similar study with data from the VSD of the 2005-06 and 2006-07 seasons also found that pregnant women are not at increased risk of miscarriage due to having been vaccinated against influenza. However, a study of the 2010-2012 flu seasons revealed that women in early pregnancy who have received the flu vaccine twice in a year had a higher risk of miscarriage within 28 days of receiving the second vaccine. A limitation of this study was the small sample size, which may have yielded imprecise results. In response to the findings of a study of the 2010-2012 influenza season, CDC funded a follow-up VSD study during the 2012-2015 flu seasons that enrolled three times as many women and found no association between flu vaccination and miscarriage. More information is available on this topic at CDC.
- Using data from the VSD project, a large study did not find an increased risk of adverse obstetric events (such as chorioamnionitis, preeclampsia, gestational hypertension) in pregnant women who received influenza vaccines between 2002 and 2009, compared to pregnant women who were not vaccinated.
- A VSD study compared pregnant women who had received the flu shot to an equivalent number of pregnant women who did not receive it during the 2004/05 and 2008/09 seasons. This study found no difference between the two groups in rates of preterm birth or young babies based on gestational age.
- A vast study conducted in August 2017 with data from VSD external site icon found that the babies of women who received the injectable flu vaccine during the first trimester did not show an increased risk of having children with serious birth defects.
Where should pregnant women get vaccinated?
Pregnant women have many options for where to get the injectable flu vaccine, including their healthcare provider’s office, workplace, grocery store, or supermarket.
All of these sites offer licensed vaccines approved for use in the US If you’ve never had a problem before after getting a flu shot, then there’s no reason not to get vaccinated at the workplace, in a store, or in a supermarket.
What is known about thiomersal in flu vaccines? Should Pregnant Women Get Thimerosal-Free Flu Vaccines?
Studies have shown that the small amount of thimerosal in vaccines does not cause any harm. Thimerosal-free flu vaccines are available for people who want to avoid it. More information is available about thimerosal in thiomersal and flu vaccines.
Can a woman who is breastfeeding get a flu vaccine?
Yes. Women who are breastfeeding should get the flu vaccine to protect themselves from the disease. Vaccination lowers a mother’s risk of getting sick and passing the flu to her babies, thus protecting them from the disease as well. This is especially important for children younger than 6 months as they are too young to get the flu vaccine.
