Getting the flu while pregnant is more serious than getting it at any other time in your life. Your body undergoes significant changes during pregnancy, including shifts in immune function, increased heart rate, and reduced lung capacity, all of which make it harder to fight off influenza. The good news: prompt treatment with antivirals is considered safe during pregnancy and can significantly reduce the risk of complications for both you and your baby.
Why the Flu Hits Harder During Pregnancy
Pregnancy naturally dials down parts of your immune system so your body doesn’t reject the developing baby. That trade-off leaves you more vulnerable to infections like influenza. At the same time, your heart is pumping more blood, your lungs have less room to expand as the uterus grows, and your oxygen demands are higher. These combined changes mean a respiratory virus that might knock you out for a week under normal circumstances can escalate to pneumonia, respiratory distress, or a hospital stay when you’re pregnant.
The CDC classifies pregnant and postpartum women as a high-risk group for severe influenza illness. In population-based surveillance data, roughly 2 in every 1,000 pregnant women were hospitalized for flu-related respiratory illness per influenza season, and about 1.8% of those hospitalized required intensive care.
Risks to Your Baby
Influenza during pregnancy doesn’t just affect you. A CDC study published in The Lancet Infectious Diseases found that flu illness during pregnancy was associated with reduced average birthweight in full-term newborns and an increased risk of late pregnancy loss (loss after 13 weeks). Women who had respiratory symptoms combined with fever faced a higher risk of preterm birth.
Historical data paints an even starker picture for severe cases. In older pandemic studies, roughly one quarter of pregnancies complicated by uncomplicated influenza ended in pregnancy loss. When the flu progressed to pneumonia, that figure climbed to more than half. Modern medical care has dramatically improved outcomes, but the underlying vulnerability remains real.
Fever Is a Specific Concern in Early Pregnancy
High fever during the weeks around conception and very early pregnancy carries its own risk. Research from the Slone Epidemiology Center Birth Defects Study found that fever in the periconceptional period (roughly the month before and after your last menstrual period) was linked to a 2.4 times higher risk of neural tube defects like spina bifida. That risk was substantially lower in women who were taking at least 400 micrograms of folic acid daily, which cut the association roughly in half. This is one reason prenatal vitamins with folic acid are recommended before and during early pregnancy, and why controlling fever quickly matters.
Symptoms That Need Immediate Attention
Most flu symptoms during pregnancy look the same as they would otherwise: fever, body aches, cough, fatigue, sore throat. But certain warning signs mean you should call 911 or go to an emergency room right away:
- Trouble breathing or shortness of breath
- Decreased or no movement from your baby
- A high fever that doesn’t respond to acetaminophen
- Dizziness, confusion, or difficulty staying awake
- Ongoing pain or pressure in your chest or abdomen
- Fever or cough that keeps coming back or worsens
- Severe muscle pain or extreme weakness
- Seizures
- Very little or no urination for an extended period
Antiviral Treatment During Pregnancy
If you suspect you have the flu, contact your healthcare provider as soon as possible. Antiviral medication (most commonly oseltamivir, the oral form sold as Tamiflu) is recommended for all pregnant women with suspected or confirmed influenza. Treatment works best when started within 48 hours of your first symptoms, though it can still help if started later.
These medications are classified as “Pregnancy Category C,” meaning no controlled clinical trials have been done in pregnant women. That sounds alarming, but multiple observational studies, at least ten published between 2009 and 2018, have consistently found that antiviral treatment during pregnancy does not increase the risk of adverse events or harmful pregnancy outcomes. The benefits of treatment clearly outweigh the theoretical risks, which is why every major health organization recommends it.
The Flu Vaccine During Pregnancy
The inactivated flu vaccine can be given during any trimester of pregnancy. Both the CDC and the American College of Obstetricians and Gynecologists recommend it for all women who are or will be pregnant during flu season. A large 2017 study found no increased risk of major birth defects in babies whose mothers received the flu shot during the first trimester, and multiple studies have shown no higher risk of miscarriage.
One important distinction: the nasal spray vaccine (live attenuated influenza vaccine) is not safe during pregnancy. Only the injected, inactivated version or the recombinant version should be used.
Timing matters for your baby’s protection too. If you’re in your first or second trimester, September or October is the ideal window. If you’re in your third trimester, getting vaccinated as early as July or August can be worthwhile because vaccination later in pregnancy transfers more protective antibodies to your baby before birth.
How Your Flu Shot Protects Your Newborn
Babies can’t receive their own flu vaccine until they’re 6 months old, which leaves a vulnerable gap. When you get vaccinated during pregnancy, your body produces antibodies that cross the placenta and give your newborn passive immunity during those critical early months.
The numbers are meaningful. Maternal flu vaccination reduced the overall risk of flu in infants under 6 months by about one third. For more serious outcomes, the protection was even stronger: a 20% reduction in emergency department visits and a 40% reduction in hospitalizations. Infants younger than 3 months benefited the most, with a 50% reduction in flu-related hospitalizations and ER visits. And mothers who were vaccinated later in pregnancy (closer to delivery) passed along even higher levels of protection.
Managing Flu Symptoms Safely
Acetaminophen (Tylenol) is the go-to option for bringing down fever and easing body aches during pregnancy. Keeping fever controlled is especially important given the link between high maternal temperature and birth defects in early pregnancy. Stay hydrated, rest as much as possible, and monitor your baby’s movement patterns in the second and third trimesters. A noticeable decrease in fetal movement is one of the clearest signals that something may need medical evaluation.
Avoid ibuprofen and aspirin unless specifically directed by your provider, as these carry their own risks during pregnancy. Many over-the-counter cold and flu combination products contain ingredients that aren’t recommended during pregnancy, so check with your provider or pharmacist before taking anything beyond acetaminophen.