Fever during pregnancy

Is it dangerous to have a fever during pregnancy? Here are the links between fever and possible pregnancy complications, plus the best ways to reduce your fever.

woman lying on the couch feeling ill
Photo credit: / visualspace

How to tell if you have a fever during pregnancy

It's not uncommon during pregnancy to feel flushed and warmer than usual, but measure your temperature with a thermometer if you're concerned.

A fever is a normal response to infections, and just like anyone, pregnant women can come down with an illness that causes a fever. If you don't already have a reliable thermometer in the house, this is a good time to get one.

Advertisement | page continues below

A temperature of over 100.4 degrees Fahrenheit (38 degrees Centigrade) is considered a fever.

If you have a fever, talk to your healthcare provider and see if you can identify the cause – and if treatment is needed, get started on it right away.

What can cause a fever in pregnancy?

A fever during pregnancy may be caused by the same things that cause a fever when you're not pregnant, such as a bacterial or viral infection (like a cold or flu), food poisoning, or a urinary tract infection (UTI). In fact, you're more susceptible to all illnesses while you're pregnant because of your suppressed immune system. (Pregnant women are ten times more likely to contract listeriosis, for example, than the general population.)

To minimize your chances of infections that cause fever, take practical steps such as washing your hands often, avoiding contact with people who are sick, and getting a flu shot and COVID-19 vaccine. Also be sure to follow food safety guidelines, such as washing your produce thoroughly and avoiding undercooked meat and eggs.

Read more about foods and beverages to avoid during pregnancy.

Can a fever during pregnancy harm my baby?

A fever during pregnancy can be harmful to a baby, but it usually isn't. Twenty percent of pregnant women in the U.S. have a fever at least once during their pregnancy, and the vast majority of them have healthy babies. A fever is least worrisome if it's low (below 101 degrees F) and if it's short lived.

Research is ongoing, but some studies have shown links between fever in pregnancy and:

Advertisement | page continues below

Some researchers suggest that risks are higher when the fever is untreated. Others conclude that taking the recommended daily dose of folic acid (400 mcg) before and during pregnancy lessens the risk of NTDs from fever during pregnancy.

Not all research supports these links. One Danish study of more than 77,000 pregnant women and their children born between 1996 and 2002 concluded that there was no association between maternal fever in pregnancy and the risk of birth defects.

Is a fever in early pregnancy dangerous?

A fever in very early pregnancy can be more dangerous (compared to later pregnancy) because fetal structures are still forming. Fever in early pregnancy raises your baby's risk of neural tube defects (NTDs) such as spina bifida, anencephaly, and encephalocele. That's because the neural tube – which forms the baby's spinal cord – is developing in the first six weeks of pregnancy.

Women who had a fever just before or during early pregnancy are twice as likely to have a baby with an NTD than women who didn't have a fever. And women who had a fever and didn't consume 400 mcg of folic acid daily had the highest risk of having a baby with an NTD.

Advertisement | page continues below

Once the neural tube is closed – at the beginning of the sixth week – your baby is no longer vulnerable to a fever-caused NTD.

Rest assured that in spite of a fever, the absolute risk of an NTD is low – especially if you take a daily prenatal vitamin with at least 400 mcg of folic acid. Routine screening for NTD is done in the second trimester with a blood test and an ultrasound scan.

Read more about your prenatal testing options.

Is fever a sign of pregnancy?

No, fever isn't a sign of pregnancy, though some women experience a slight rise in temperature along with the rise in progesterone that happens in early pregnancy.

The progesterone – and temperature – rise starts right after ovulation, which is why charting your temperature can help you conceive. Once you're pregnant, your body continues producing progesterone, which helps maintain a healthy uterine lining, keeps your body from having contractions as your uterus grows, and helps your body prepare for breastfeeding.

Advertisement | page continues below

The temperature rise that happens as your progesterone starts to increase is a small, normal uptick that stays well below the 100.4 F fever threshold.

Does fever in pregnancy increase the risk of autism, attention deficits, or developmental delays?

We don't know for certain, because research is ongoing, but there have been some studies linking fever in pregnancy and an increased risk of autism spectrum disorder (ASD), attention deficits, and developmental delay (DD).

(Keep in mind that retrospective studies – which ask subjects to report distant past symptoms – are considered less reliable than prospective studies – which gather information in real time. For example, a prospective study might ask moms while they're pregnant if they're having a fever, and a retrospective one might ask women years later to remember a fever during pregnancy.)

Here's some of what we know:

  • One retrospective study analyzed data from more than 500 children with ASD and over 160 with DD and found an association between maternal fever and both conditions. They also found that the ASD risk was less among mothers who took medication to lower their fevers.
  • A prospective Norwegian study of more than 114,000 children found an association of prenatal fever and increased ASD risk, especially (but not exclusively) in the second trimester. These researchers concluded that the risks were slightly lessened by the use of acetaminophen and increased markedly with fever frequency (three or more fever episodes), especially after 12 weeks' gestation. Data from the same study indicated that maternal fever in early pregnancy may be a risk factor for ADHD, and especially for inattention problems.
  • A large multisite retrospective study of children with ASD and DD who were born in the United States between 2003 and 2006 concluded that women who had an infection accompanied by a fever during the second trimester of pregnancy are more likely to have children with ASD.
  • A prospective study examining the motor development of children whose mothers had a fever during pregnancy found a significant association between maternal fever during pregnancy and developmental coordination disorder (DCD) in 7-year olds.
Advertisement | page continues below

Though the findings of these studies can be concerning, especially if you have a fever or fevers during pregnancy, keep in mind that the absolute risk of these outcomes is low.

Medicines to take for fever during pregnancy

The best medication to take to lower your fever when you're pregnant is acetaminophen. In addition to making you feel better, acetaminophen will lower your body temperature – which may reduce risks for your baby. It's a good idea to take acetaminophen to bring down your fever as soon as possible.

However, before taking any medication while pregnant make sure to talk with your healthcare provider about safe medications during pregnancy. Don't take more than recommended dosages and total daily amounts indicated on the label. Taking too much acetaminophen can be bad for your liver and – later in pregnancy – your baby's liver. Learn more about the safety of acetaminophen in pregnancy.

Other ways to treat a fever while pregnant

In addition to taking medication, here are some things that can help lower your fever:

  • Lie down and place a cool, damp washcloth on your forehead.
  • Take a lukewarm tub bath or sponge bath. Avoid using cold water, since it can cause you to shiver, leading to a spike in temperature. Lukewarm water will work fine – your fever will fall as the water evaporates off your skin. (You may have heard that a sponge bath using rubbing alcohol will bring down a fever. Don't try this, as it can cool you down too quickly, prompting your body to reheat even further. Breathing in the vapors can be harmful, too.)
  • Drink plenty of fluids to stay hydrated and help cool your body from the inside out.
  • Turn on a fan. Don't let it blow directly on you, because that could cause you to become chilled. Instead, put it on a low setting and let it circulate the air around you.
  • Dress in one light layer of clothing. If you get chilled, wrap yourself in a light blanket until you're warm enough to remove it.
  • Stay indoors in a cool place.
Advertisement | page continues below

When should I call my healthcare provider for a fever?

If you're concerned about having a fever during pregnancy, call your doctor or midwife. Also, contact your provider if you have a fever that lasts more than a day or two. Also call if you have:

Whether or not you're running a fever, it's a good idea to know what warrants a call to your healthcare provider. Read our article on pregnancy symptoms you should never ignore.

Learn more:

Advertisement | page continues below
Follow your baby's amazing development

BabyCenter's editorial team is committed to providing the most helpful and trustworthy pregnancy and parenting information in the world. When creating and updating content, we rely on credible sources: respected health organizations, professional groups of doctors and other experts, and published studies in peer-reviewed journals. We believe you should always know the source of the information you're seeing. Learn more about our editorial and medical review policies.

ACOG. 2018. Listeria and pregnancy. American College of Obstetricians and Gynecologists. a new window [Accessed May 2021]

Croen L et al. 2019. Infection and fever in pregnancy and autism spectrum disorders: Findings from the study to explore early development. Autism Research 12(10): 1551-1561. a new window [Accessed May 2021]

Gustavson K et al. 2019. Maternal fever during pregnancy and offspring attention deficit hyperactivity disorder. Scientific Reports 9, 9519. a new window [Accessed May 2021]

Holst C et al. 2015. Fever during pregnancy and motor development in children: a study within the Danish National Birth Cohort. Developmental Medicine & Child Neurology 57(8): 725-32. a new window [Accessed May 2021]

Hornig M et al. 2018. Prenatal fever and autism risk. Molecular Psychiatry 23(3): 759-766. a new window [Accessed May 2021]

Kerr Set al. 2017. Preconceptional maternal fever, folic acid intake and the risk for neural tube defects. Annals of Epidemiology 27(12):777.-782 e.1 a new window [Accessed May 2021]

MothertoBaby. 2020. Hyperthermia. a new window [Accessed May 2021]

Sass L et al. 2017. Fever in Pregnancy and the Risk of Congenital Malformations: a Cohort Study. BMC Pregnancy and Childbirth 17:413. a new window [Accessed May 2021]

Yang G et al. 2021. Maternal fever during preconception and conception is associated with congenital heart diseases in offspring: An updated meta-analysis of observational studies. Medicine 100(9): e24899. a new window [Accessed May 2021]

Zerbo O et al. 2013. Is maternal influenza or fever during pregnancy associated with autism or developmental delays? Results from the CHARGE (Childhood Autism Risks from Genetics and Environment) Study. Journal of Autism and Developmental Disorders 43(1): 25-33. a new window [Accessed May 2021]

Karen Miles
Karen Miles is a writer and an expert on pregnancy and parenting who has contributed to BabyCenter for more than 20 years. She's passionate about bringing up-to-date, useful information to parents so they can make good decisions for their families. Her favorite gig of all is being "Mama Karen" to four grown children and "Nana" to nine grandkids.