The information provided below is for readers based in the United States of America. Readers outside of the United States of America should seek the information from local sources.

What is the flu (influenza)?

The influenza virus is highly contagious and causes respiratory illness commonly known as “flu”. The flu is passed from person-to-person when an infected individual coughs or sneezes and a healthy person breaths-in the virus. It can also be passed if a person touches an item, like a door handle, for example, that was previously touched by an ill person, and then touches their nose, mouth, or eyes. Adults are contagious 1 day before they get symptoms and up to 7 days after they first get sick. Children are contagious for even longer periods than adults.

While a pregnant woman does not have a higher chance of getting the flu during pregnancy, they are more likely to get a severe form of the illness. They are four times more likely to be hospitalized with the flu and die from complications of the flu than a non-pregnant person.

How common is the flu (influenza) during pregnancy?

Each year approximately 5-20% of people in the United States will get the flu. The flu is responsible for over 200,000 hospitalizations and 3,300 to 49,000 deaths per year.

During the 2009-2010 H1N1 flu pandemic, pregnant women accounted for 5 percent of H1N1 deaths but only represented about one percent of the general population. They were more likely to be admitted to the hospital, receive care in the ICU, and require treatment with a ventilator compared to non-pregnant patients. This was especially true for women who had chronic respiratory problems like asthma. The H1N1 pandemic confirmed that pregnant women are at higher risk for complications from the flu, including death.

How is flu (influenza) diagnosed during pregnancy?

The flu can be diagnosed based on symptoms alone, especially when the flu is known to be active in the community. Flu symptoms tend to start abruptly, frequently over a matter of hours, rather than gradually. The flu can cause any of the following symptoms:

  • Fever or chills
  • Headache
  • Muscle aches
  • Feeling very tired
  • Cough
  • Sore throat
  • Runny or stuffy nose
  • Vomiting and diarrhea – tends to be more common in children

These symptoms tend to last about a week but pregnant women may have them for longer.

If the diagnosis of the flu is unclear, there is a rapid flu test that can be done in the doctors office and usually gives results in about 15 minutes. A swab of the nose or back of the throat is taken for the test.

Does the flu (influenza) cause problems during pregnancy?

Besides having a higher chance of developing complications of the flu, pregnant women have a higher risk of the following:

  • Miscarriage – this occurs if you get the flu during the first 13 weeks of the pregnancy
  • Deliver before 37 weeks of gestation
  • Poorly grown babies
  • Stillbirth

Does the flu (influenza) during pregnancy cause problems for the baby?

The risks of influenza on the growing baby have not been well studied but there is some evidence that shows an increase in certain types of birth defects. These include:

  • Cleft lip (an abnormal slit in the upper lip)
  • Heart defects
  • Abnormally developed brain, spine, or spinal cord called a neural tube defect
  • Increased fluid around the brain called hydrocephaly

High fever that can occur with the flu has also been shown to cause an increased risk of abnormally developed brain, spine, or spinal cord.

The chance of the baby having any of these birth defects depends on when in the pregnancy maternal flu occurred. The highest risk is during the first 13 weeks of the pregnancy.

What to consider about taking medications when you are pregnant or breastfeeding:

  • The risks to yourself and your baby if you do not treat the flu
  • The risks and benefits of each medication you use when you are pregnant
  • The risks and benefits of each medication you use when you are breastfeeding

What should I know about using medication to treat the flu (influenza) during pregnancy?

If a pregnant woman gets the flu during pregnancy, antiviral medicine is usually given to help shorten the time of illness and decrease the chance of developing severe illness. These medicines need to be started within two days of getting sick, so it is important to see your doctor right away if you think you have the flu.

Because there is a high risk of hospitalization or death from flu complications, pregnant women are encouraged to take antiviral medicines. It is also recommended that fevers be treated with a medicine like acetaminophen, to decrease the chance of birth defects that have been associated with high fevers during the first trimester of pregnancy.

What should I know about choosing a medication for my flu (influenza) during pregnancy?

There are currently three different medicines used in the US to treat the flu: oseltamivir (Tamiflu), inhaled zanamivir (Relenza), and intravenous peramivir (Rapivab). All three medications are safe for use in pregnancy and are equally effective at treating the flu.

Oseltamivir is a pill and is the most commonly used antiviral in pregnancy. Zanamivir is a nasal mist that should not be used in patients with a history of allergy to milk protein or in people with chronic respiratory disorders, like asthma. Peramivir is only used for patients who are in the hospital because it must be given through an IV.

You may find Pregistrys expert reports about the individual medications to treat the flu here. Additional information can also be found in the sources listed at the end of the report.

What should I know about taking a medication for my flu (influenza) when I am breastfeeding?

Oseltamivir appears to be safe for use during breastfeeding. Although no data are available about the safety of zanamivir in lactation, it is considered safe for use in breastfeeding women.

Generally, it is not recommended that mothers infected with the flu nurse their babies because of the potential risk of passing the flu to the baby. It is safe to continue pumping breastmilk while ill, but a healthy individual should give the expressed milk to the baby.

What alternative therapies besides medications can I use to treat my flu (influenza) during pregnancy?

There are no alternative therapies for treating the flu. Receiving a flu vaccine during pregnancy to prevent flu infection is the best advice for all pregnant women. The flu vaccination is made from killed portions of the flu virus, so there is no possibility that it will give a person the flu. Many people do feel achy, tired, and even a bit feverish after the vaccination, but this is just the immune system’s normal response to the vaccine. The vaccination is safe for use during the entire pregnancy; however, the intranasal vaccine is not recommended during pregnancy but is considered safe for use during breastfeeding.

Some women express concern about the thimerosal preservative used in the flu vaccine because there have been suggestions that it can lead to autism. Studies have not shown that this association exists, so both the CDC and the FDA continue to support its use in vaccines
administered to pregnant women. Thimerosal-free versions of the vaccine are available.

An added benefit to receiving the flu vaccine during pregnancy is that it passes immunity to the infant for up to 6 months after birth. Since infants cannot receive the flu vaccine until they are 6 months old, this is the best way to protect an infant from the flu.

The flu vaccine is not 100% effective, so if a person has a known exposure to the flu, then preventive treatment with antiviral medication is recommended. Both oseltamivir and zanamivir can be taken for a minimum of ten days to help reduce the chances of getting the flu.

What can I do for myself and my baby when I have the flu (influenza) during pregnancy?

If you get the flu during pregnancy, get lots of rest, drink plenty of fluids, and try eating small meals when you feel that you can. To avoid passing the flu to others, it is recommended that you stay home and limit contact with other people.

Resources for flu (influenza) during pregnancy:

For more information about the flu during and after pregnancy, call at 800-994-9662 (TDD: 888-220-5446) or contact the following organizations:


Read the whole report
General information

It is very common for women to worry about having a miscarriage or giving birth to a child with a birth defect while they are pregnant. Many decisions that women make about their health during pregnancy are made with these concerns in mind.

For many women these concerns are very real. As many as 1 in 5 pregnancies end in a miscarriage, and 1 in 33 babies are born with a birth defect. These rates are considered the background population risk, which means they do not take into consideration anything about the health of the mom, the medications she is taking, or the family history of the mom or the baby’s dad. A number of different things can increase these risks, including taking certain medications during pregnancy.

It is known that most medications, including over-the-counter medications, taken during pregnancy do get passed on to the baby. Fortunately, most medicines are not harmful to the baby and can be safely taken during pregnancy. But there are some that are known to be harmful to a baby’s normal development and growth, especially when they are taken during certain times of the pregnancy. Because of this, it is important to talk with your doctor or midwife about any medications you are taking, ideally before you even try to get pregnant.

If a doctor other than the one caring for your pregnancy recommends that you start a new medicine while you are pregnant, it is important that you let them know you are pregnant.

If you do need to take a new medication while pregnant, it is important to discuss the possible risks the medicine may pose on your pregnancy with your doctor or midwife. They can help you understand the benefits and the risks of taking the medicine.

Ultimately, the decision to start, stop, or change medications during pregnancy is up to you to make, along with input from your doctor or midwife. If you do take medications during pregnancy, be sure to keep track of all the medications you are taking.

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