Getting sick while pregnant is common and, in most cases, does not harm your baby. Ordinary colds, mild stomach bugs, and sore throats typically resolve on their own without any lasting effects on your pregnancy. That said, your body does handle infections differently when you’re pregnant, and certain illnesses deserve closer attention. Knowing what’s routine and what’s a red flag can save you a lot of worry.
Why You Get Sick More Easily During Pregnancy
Your immune system doesn’t shut down during pregnancy, but it does shift gears. Early in pregnancy, your body dials back the aggressive, inflammation-driven side of its immune response and leans more heavily on the antibody-producing side. This rebalancing prevents your immune system from attacking the developing baby, who carries genetic material from both parents and would otherwise look “foreign” to your defenses. Special regulatory immune cells actively suppress inflammatory reactions near the uterus, which is essential for implantation and healthy placental growth.
The trade-off is that certain infections hit harder. Influenza, chickenpox, and hepatitis E are all associated with more severe illness in pregnant women compared to the general population. Your body also makes physical changes, like increased blood volume and a compressed diaphragm, that can turn a routine respiratory infection into something more uncomfortable. None of this means every cold will become dangerous, but it does explain why you might feel worse than usual or take longer to bounce back.
When a Common Cold or Flu Is Just a Cold or Flu
A runny nose, mild cough, body aches, or a low-grade temperature are not emergencies. Most viral upper respiratory infections last 7 to 10 days and pose no direct threat to your baby. The key is managing symptoms comfortably and staying hydrated.
For congestion, saline nasal rinses (a neti pot or saline spray), nasal strips, and a cool-mist humidifier are all safe throughout pregnancy. Increasing your fluid intake helps thin mucus and supports your sinuses in draining. For a sore throat, gargling with warm salt water is simple and effective. These low-tech options handle the majority of cold symptoms without any medication at all.
If you need more relief, your options are narrower than usual. Acetaminophen (Tylenol) is considered the safest pain and fever reducer during pregnancy. Ibuprofen, naproxen, and other anti-inflammatory painkillers should be avoided, especially from 20 weeks onward. The FDA warns that these medications can reduce the baby’s kidney function and lower amniotic fluid levels. After 30 weeks, they also carry a risk of causing premature closure of a blood vessel near the baby’s heart. For antihistamines, chlorpheniramine is one of the few specifically recommended by both ACOG and the allergy specialist guidelines. Oral decongestants containing pseudoephedrine are generally acceptable after the first trimester but are best avoided in early pregnancy due to a small increased risk of abdominal wall defects.
Fever Is the Symptom to Watch Most Closely
A persistent fever matters more than the infection causing it. According to the March of Dimes, a temperature above 103°F (39.4°C) during the first trimester is associated with increased risks of miscarriage, congenital heart defects, and cleft lip or palate. There is also emerging (though not yet conclusive) research linking high early-pregnancy fevers to autism spectrum disorder.
The CDC considers a temperature of 100.4°F (38°C) or higher during pregnancy a reason to contact your healthcare provider. If you develop a fever, bringing it down promptly with acetaminophen and fluids is a reasonable first step, but don’t wait to see if it resolves on its own over days. A fever from the flu is especially worth reporting, because antiviral treatment is most effective when started early and pregnant women qualify as a high-risk group for complications.
Stomach Bugs and the Dehydration Risk
A bout of vomiting or diarrhea from a stomach virus is unpleasant but usually short-lived. The illness itself rarely crosses the placenta. The real concern is dehydration. When you’re pregnant, your fluid needs are already higher, and losing fluids rapidly through vomiting or diarrhea can drop your reserves fast. Dehydration during pregnancy has been linked to low amniotic fluid levels and, in severe cases, neural tube defects if it occurs very early.
If you can’t keep fluids down for more than several hours, or you notice dry mouth, dark urine, dizziness, or confusion, that warrants medical attention. Small, frequent sips of water or an electrolyte drink are more effective than trying to gulp a full glass at once.
Foodborne Illness Requires Extra Caution
Not all stomach symptoms come from a simple virus. Listeria is a bacterial infection that deserves special mention because pregnant women are about 10 times more likely to contract it than other healthy adults. The symptoms can be deceptively mild: low-grade fever, muscle aches, nausea. Some women feel almost nothing. But listeriosis can cause miscarriage, stillbirth, premature delivery, or serious health problems in the newborn, including meningitis, seizures, and organ damage.
Symptoms can appear days or even weeks after eating contaminated food. The highest-risk foods include deli meats that haven’t been reheated, soft cheeses made with unpasteurized milk, smoked seafood, and pre-made salads from refrigerated cases. If you’ve eaten something questionable and develop even mild flu-like symptoms, mention the possible exposure to your provider. Listeria is treatable with antibiotics when caught early.
Vaccines That Protect You and Your Baby
Prevention is more effective than treatment for the infections that pose the greatest pregnancy risks. Three vaccines are currently recommended during pregnancy:
- Flu shot: Safe at any point during pregnancy and given seasonally. If you’re in your first or second trimester, September or October is ideal timing. Third-trimester vaccination can also pass protective antibodies to your baby, covering them during the first months of life before they’re old enough for their own flu shot.
- Tdap (whooping cough): Recommended during each pregnancy, ideally between 27 and 36 weeks. This timing maximizes the antibodies that transfer to your baby before birth.
- RSV vaccine: A single dose between 32 and 36 weeks of gestation, given during RSV season (September through January in most of the U.S.), protects infants under 6 months from severe lower respiratory tract infection.
Warning Signs That Need Immediate Attention
Most illnesses during pregnancy are manageable at home, but some symptoms signal something more serious. The CDC identifies these as urgent maternal warning signs:
- Fever of 100.4°F or higher
- Severe nausea or vomiting that prevents you from keeping down any fluids, especially with dry mouth, confusion, or fever
- Decreased fetal movement: a noticeable drop or stop in your baby’s usual pattern of kicks and rolls
- Trouble breathing: sudden shortness of breath, chest tightness, or difficulty breathing while lying down
- Severe headache that won’t go away, worsens, or comes with blurred vision or dizziness
- Vaginal bleeding or fluid leaking
- Severe belly pain that is sharp, sudden, or worsening
- Dizziness or fainting
- Leg swelling with redness or pain, particularly in one calf, which could indicate a blood clot
These symptoms can overlap with illness, which makes them easy to dismiss as part of being sick. A stomach bug shouldn’t cause belly pain that gets progressively worse. A cold shouldn’t leave you unable to catch your breath at rest. If something feels different from ordinary sick-day discomfort, trust that instinct.