Getting sick while pregnant is not automatically dangerous, but it does carry more risk than when you’re not pregnant. Your immune system naturally dials down during pregnancy to protect the developing baby, which means your body is slower to fight off infections and more likely to develop complications from illnesses that would otherwise be mild. The severity of the risk depends entirely on what you’re sick with, how far along you are, and whether you develop a fever.
Why Pregnancy Makes You More Vulnerable
Your immune system shifts during pregnancy. It doesn’t shut down, but it becomes less aggressive so your body won’t reject the fetus. This trade-off means common infections like the flu or a cold can hit harder and last longer. Your heart and lungs are also working overtime, pumping up to 50% more blood and breathing for two, so respiratory infections in particular can escalate faster than they would outside of pregnancy.
The Common Cold Is Usually Fine
A standard cold with sneezing, a runny nose, and a mild sore throat poses very little risk to your baby. The virus stays in your upper respiratory tract and doesn’t cross the placenta. The main concern is your comfort and staying hydrated. Most colds resolve on their own within a week or two, and the baby won’t be affected.
Where things get slightly more complicated is symptom management. Not all over-the-counter cold medications are safe during pregnancy. Acetaminophen remains the safest option for pain and fever relief, though the FDA has noted that prolonged, chronic use throughout pregnancy may be associated with a small increased risk of neurological conditions in children. Short-term use for actual symptoms is still considered the best available choice, since ibuprofen and aspirin both carry documented risks to the fetus, especially in the third trimester when they can affect fetal blood flow and kidney function.
For congestion, the cough suppressant dextromethorphan (the “DM” on cough syrup labels) appears safe throughout pregnancy. The antihistamine chlorpheniramine is a preferred option for runny nose and sneezing. However, the expectorant guaifenesin has been linked to neural tube defects when used in the first trimester during a febrile illness, so it’s best avoided early in pregnancy.
The Flu Carries Real Risks
Influenza is where being sick while pregnant gets more serious. During the 2009 H1N1 pandemic, pregnant women made up nearly 6% of all ICU admissions tied to the virus, despite representing a small fraction of the population. Among women who were hospitalized with the flu while pregnant, the odds of delivering preterm were three to four times higher than normal. Roughly 64% of babies born to mothers hospitalized with H1N1 arrived early, compared to about 12% of births nationally.
The seasonal flu isn’t typically as severe as the 2009 pandemic strain, but pregnancy still puts you in a higher-risk category every flu season. Getting a flu vaccine during pregnancy is one of the most effective preventive steps you can take.
COVID-19 and Preterm Birth
COVID-19 infection during pregnancy roughly doubles the odds of preterm birth overall. The risk is highest in the third trimester, where infection triples the odds of early delivery. First and second trimester infections don’t show the same statistically significant increase, though the trend still leans toward higher risk. Staying current on COVID vaccinations during pregnancy reduces the chance of severe illness.
Why Fever Is the Biggest Concern
Across nearly all types of illness, the single factor that raises the most concern during pregnancy is fever. A sustained high temperature, particularly in the first trimester, has been associated with an increased risk of certain birth defects, including neural tube defects. The CDC defines a fever worth acting on during pregnancy as 100.4°F (38°C) or higher.
If you develop a fever, bringing it down promptly matters. Acetaminophen is the go-to choice. Staying well-hydrated helps too, since dehydration can make fever worse and, on its own, may contribute to uterine irritability. There is a hypothesis that dehydration triggers the release of a hormone structurally similar to oxytocin (the hormone that causes contractions), though research has not consistently confirmed a direct link between hydration levels and premature contractions. Still, keeping up with fluids when you’re sick is one of the simplest things you can do to support your pregnancy.
Foodborne Illness Is Rarer but More Dangerous
Stomach bugs from food are a different category of risk. Listeria, the bacteria found in unpasteurized cheese, deli meats, and some ready-to-eat foods, infects roughly 1 in 25,000 pregnant women each year in the United States. That sounds rare, and it is, but the consequences are severe: about 1 in 4 pregnant women who contract listeriosis lose their pregnancy or their baby shortly after birth. Pregnant women are roughly 10 times more likely than the general population to get sick from Listeria in the first place.
This is the reason behind the dietary precautions you’ve probably already heard: avoid soft cheeses made with unpasteurized milk, heat deli meats until steaming, and skip refrigerated smoked seafood unless it’s been cooked.
Protecting Your Baby Before Birth
Vaccines given during pregnancy do more than protect you. Getting a Tdap vaccine (for whooping cough) during the third trimester passes antibodies to your baby before birth. Research shows that babies born to mothers who received Tdap during pregnancy had a 21% lower rate of hospitalization for respiratory causes compared to babies whose mothers were not vaccinated. The flu vaccine during pregnancy has not been linked to any increase in infant hospitalization or mortality.
Warning Signs That Need Immediate Attention
Most illnesses during pregnancy are manageable at home, but certain symptoms require urgent care. Contact your healthcare provider or go to the hospital if you experience any of the following:
- Fever of 100.4°F or higher that doesn’t come down with acetaminophen
- Inability to keep fluids down for more than 8 hours, or food down for more than 24 hours
- Decreased fetal movement or a feeling that your baby has stopped moving
- Trouble breathing, tightness in your chest, or feeling like you can’t get enough air
- Severe headache that won’t respond to medication and fluids
- Vision changes like flashing lights, blind spots, or blurry vision
- Vaginal bleeding or fluid leaking beyond light spotting
These symptoms can signal complications that go beyond a normal illness, including preeclampsia or infection that has become systemic. The threshold for seeking help during pregnancy is intentionally lower than it would be otherwise. If something feels wrong, it’s worth a call.