Fever

Last Update: 06 Mar 2025

Condition

Table of content

1. What Is a Fever? 2. Why Treating During Pregnancy 3. Before Medications 4. Medication Options 5. Breastfeeding 6. Key Takeaways 7. Research limits

Welcome to our Fact Sheet on fever during pregnancy and breastfeeding. The information provided is based on current research and may be updated as new scientific knowledge emerges. The content shared does not replace personalized advice from healthcare professionals.

1. What Is a Fever and How to Recognize the Symptoms?

Fever is a rise in body temperature above the normal range. A fever is typically defined as an oral temperature of 38°C (100.4°F) or higher, or 38.3°C (101°F) when taken rectally or by ear. Fever is often a sign that your body is fighting an infection, but it can also be triggered by other factors like autoimmune conditions, allergic reactions, or even certain cancers.

Fever can be concerning during pregnancy, particularly in the first trimester. Infections are the most frequent cause, but hyperthermia (overheating due to external conditions like extreme heat, hot tubs, or heavy exercise) can also raise your body temperature and should be treated with caution.

Some symptoms of fever during pregnancy:

Elevated body temperature
Chills and shivering
Sweating
Headache
Muscle aches
Fatigue
Loss of appetite

If you notice any of these symptoms, monitor your temperature and consult your healthcare provider. Prolonged or high fever may require medical treatment to protect both you and your baby.

Did you know…? Fever during pregnancy affects around 1 in 20 pregnancies. Based in their genetics, environment, and socioeconomic status can increase your risk of having a fever. For example, some medical conditions can increase susceptibility to fever, such as sickle cell disease (more common in African, African American, and Mediterranean populations); familial Mediterranean fever (affecting Mediterranean populations such as Arabs, Jews, and Turks); or thalassemia (Asians and Mediterranean populations).

2. Why Is It Important to Treat Fever During Pregnancy?

Treating a fever during pregnancy is crucial because a prolonged or high fever can pose risks to both you and your baby. A fever is often a sign of an underlying infection or illness, and addressing it promptly helps prevent complications.

Understanding Risks in Pregnancy

Research helps us estimate the risks linked to common pregnancy-related conditions. Miscarriages, congenital malformation tooltip, premature births, and other complications can happen in any pregnancy for many reasons. These are called background risks.

So far, a high fever, especially one over 38.3°C (101°F), during the first trimester can increase the risk of certain congenital malformations tooltip, particularly neural tube defects tooltip compared to the background risk (3 out of 100 pregnancies).

Fever in later stages of pregnancy can also lead to issues like preterm labor or low birth weight (less than 5 pounds and 8 ounces [2,500 grammes]), as well as other complications related to the cause of the fever, such as infections of the urinary tract or respiratory system. Addressing the fever early reduces these risks.

Table 1 below shows possible impact of an untreated fever during pregnancy compared with the background risks. Remember that these risks can be influenced by other factors such as the pregnant person’s age, family history, ethnicity, lifestyle, and other medical conditions.

What are malformations like spina bifida?

Learn more

Table 1. Potential risks associated with untreated fever during pregnancy.

For who?	What?	What does research say?
For the pregnant person	Miscarriage	Some studies found a slight increased risk compared to the background risk tooltip. Not all of them agree.
For the pregnant person	Other complications	Fever can lead to dehydration, which may lower your amniotic fluid, and can also increase the risk of additional infections tooltip.
For the unborn child	Congenital Malformations	Some studies found a higher risk of neural tube defects tooltip and heart defect compared to the background risk tooltip.
	Growth	Some studies show a small chance of low birth weight (less 5 pounds 8 ounces [2,500 grammes]) tooltip. More research is needed to confirm this.
	Premature Birth	Some studies found a slight increased risk of giving birth before 37 weeks compared to the background risk tooltip.
For future child/adult	Brain Development	A few studies suggest a potential link between maternal fever during pregnancy and increased risk of autism spectrum disorders and attention deficit/hyperactivity disorder (ADHD) in the childtooltip. More research is needed to confirm these risks.

* The risks that increased when compared to the background chance in the population are in bold.

3. What Can I Do to Manage My Fever Before Medications?

If you’re experiencing a fever during pregnancy, there are several non-pharmacological methods you can try to help lower your temperature and improve your comfort before taking any medications:

Rest and Hydration: Make sure to rest and drink plenty of fluids, such as water or electrolyte drinks, to stay hydrated. Dehydration can worsen fever symptoms and may affect your milk supply if you’re breastfeeding.
Cool Compress: Apply a cool, damp cloth to your forehead or the back of your neck to help lower your body temperature.
Lukewarm Baths: Taking a lukewarm bath can help reduce fever. Avoid using cold water, as it can cause shivering, which may increase your body temperature.
Wear Light Clothing: Choose loose, breathable clothing to avoid overheating and allow your body to cool down naturally.
Ventilation: Ensure your living space is well-ventilated and kept at a comfortable temperature to help regulate your body heat.

These methods can provide relief, but it’s important to consult your healthcare provider if your fever persists, worsens, or is accompanied by other symptoms like chills, severe headache, or difficulty breathing. They can help determine if more treatment is needed to protect your health and your baby’s health.

4. Medication Options for Treating a Fever

If you have a fever during pregnancy, some over-the-counter (not prescribed) medications may be used to relieve your fever. For example, acetaminophen (Tylenol®) and non-steroidal anti-inflammatories (NSAIDs) (e.g. Advil® and Motrin®) can help. It’s important to always consult your healthcare provider before use, especially NSAIDs after 20 weeks of gestation.

To know more about a specific medication, please consult the associated Fact Sheet and always discuss with your healthcare provider before making changes to your medication intake during pregnancy.

Table 2. Some medications available in Canada to treat a fever

Medication Types	Medication Names	Brand Names
Pain relief	Acetaminophen, paracetamol	Tylenol®
Non-steroidal anti- inflammatory drugs (NSAIDs)	Ibuprofen	Advil®, Motrin®
	Naproxen	Naprosyn®, Aleve®
	Acetylsalicylic acid	Aspirin

Moreover, if the fever is related to an infection like urinary tract infections some antibiotics might be prescribed by your healthcare team to treat the cause of your fever and avoid additional complications.

How do I know which one to take?

Each medication has its benefits and potential risks, which is why it’s important to work with your healthcare team—including your pharmacist, nurse, doctor, or midwife—to make the best decision for you and your baby. They will guide you in making the best decision for both you and your baby by considering your symptoms, stage of pregnancy, and any other health conditions you may have.

For managing fever, acetaminophen (Tylenol®) is the preferred medication due to its long history of use and effectiveness. In contrast ibuprofen (Advil® or Motrin®) and other non-steroidal anti-inflammatories (NSAIDs) are generally avoided during certain periods of the pregnancy, namely the after 20 weeks of gestation.

Always consult with your healthcare provider to ensure you are choosing the safest and most effective option for you and your baby.

5. Will I Be Able to Breastfeed?

If breastfeeding is what you desire, know that in most cases, having a fever does not prevent you from breastfeeding. It’s important to consult your healthcare provider to determine the cause of your fever and receive the appropriate treatment as the underlying cause of the fever or the medication taken can influence whether breastfeeding is safe.

If your fever is due to a common illness like the flu or COVID-19, you can continue breastfeeding. In fact, your breast milk contains antibodies that can help protect your newborn’s health.

To reduce the risk of spreading the infection to your baby, it’s recommended to:

Wash your hands thoroughly before breastfeeding
Wear a mask while breastfeeding or handling your baby

By following these simple precautions, you can keep breastfeeding while keeping your baby safe. If you are advised to temporarily stop breastfeeding due to your condition or treatment, consider pumping and discarding milk to maintain your supply until you can safely resume.

Breastfeeding is a personal choice. Remember that if you have questions about your situation, you can seek help from your healthcare professional (doctor, nurse, pharmacist) or a lactation consultant.

Key Takeaways

Fever during pregnancy is defined as a body temperature of 38°C (100.4°F) or higher.
If left untreated, fever can pose risks to both the mother and the developing baby, especially in early pregnancy.
Rest, hydration, cool compresses, and wearing light clothing can help manage fever, but consulting your healthcare provider is essential.
Acetaminophen (Tylenol®) is the preferred medication for reducing fever during pregnancy, while ibuprofen and aspirin should be used with caution during certain periods of the pregnancy.
More studies are needed to fully understand the long-term effects of fever during pregnancy on maternal and fetal health.

Research Is Great, But It Is Not Perfect

Making informed health decisions during pregnancy also involves understanding the current scientific knowledge, which has some limitations. Here’s what our team have found about the quality and quantity of research on fever during pregnancy:

Not enough research on long-term effects: There isn’t enough information about how fever during pregnancy might affect the pregnant person or baby in the long run, especially when it comes to the child’s brain development and growth.
Different causes, different risks: Fever during pregnancy can happen for many reasons (infections, immune system issues, overheating), so it’s hard to say for sure how risky it is in every situation.
Some groups are not well studied: Research doesn’t always include people from different backgrounds, meaning it might not fully reflect how factors like income, environment, or genetics affect fever risks.
Unclear guidance on non-medication treatments: There isn’t much agreement on how well non-medication treatments like drinking fluids or cooling work, because studies don’t always use the same methods to test them.

These factors can affect the accuracy and reliability of current research, which is why it’s important to consult your healthcare team for personalized advice.

For more information, you can also consult the following resources:

Centers for Disease Control and Prevention (CDC): “Pregnant? Don’t Overlook Fever” https://www.cdc.gov/pregnancy/features/treating-for-two/fever.html
American College of Obstetricians and Gynecologists (ACOG): “Fever During Pregnancy” https://www.acog.org/womens-health/faqs/fever-during-pregnancy
MotherToBaby: “Hyperthermia” https://mothertobaby.org/fact-sheets/hyperthermia-pregnancy/

References

Naître et grandir. Fever During Pregnancy. Updated September 2021. https://naitreetgrandir.com/en/pregnancy/first-trimester/fever-during-pregnancy/.
Healthline. Fever During Pregnancy: Will It Affect My Baby? https://www.healthline.com/health/pregnancy/could-fever-harm-my-baby.
“Genetics and Inheritance Patterns.” MedlinePlus. https://medlineplus.gov/genetics/understanding/inheritance/ethnicgroup/.
National Center for Biotechnology Information. Fever and Hyperthermia. https://www.ncbi.nlm.nih.gov/books/NBK560754/.
Boston Medical Center. Ancestry-Based Genetic Services. https://www.bmc.org/genetic-services/ancestry-based.
Hcini, N., et al. “Causes and Consequences of Fever in Amazonian Pregnant Women: A Large Retrospective Study from French Guiana.” PLoS Neglected Tropical Diseases, vol. 17, no. 10, 2023, e0011721. doi:10.1371/journal.pntd.0011721.
Chansamouth, V., et al. “The Aetiologies and Impact of Fever in Pregnant Inpatients in Vientiane, Laos.” PLoS Neglected Tropical Diseases, vol. 10, no. 4, 2016, e0004577. doi:10.1371/journal.pntd.0004577.
MyHealth Alberta. Fever During Pregnancy. Current as of August 6, 2023. https://myhealth.alberta.ca/Health/pages/conditions.aspx?hwid=tm6620&lang=en-ca.
Villines, Z. “Fever During Pregnancy: Risks and When to Seek Help.” Medical News Today, December 24, 2019. https://www.medicalnewstoday.com/articles/327385.
Chersich, M. F., et al. “Associations Between High Temperatures in Pregnancy and Risk of Preterm Birth, Low Birth Weight, and Stillbirths: Systematic Review and Meta-Analysis.” BMJ, vol. 371, 2020, m3811. doi:10.1136/bmj.m3811.
Egloff, C., et al. “Causes and Consequences of Fever During Pregnancy: A Retrospective Study in a Gynecological Emergency Department.” Journal of Gynecology Obstetrics and Human Reproduction, vol. 49, no. 9, 2020, p. 101899.
Dreier, John W., et al. “Fever and Infections in Pregnancy and Risk of Attention Deficit/Hyperactivity Disorder in the Offspring.” Journal of Child Psychology and Psychiatry, vol. 57, no. 4, 2016, pp. 540-548.
Yang, G., et al. “Maternal Fever During Preconception and Conception Is Associated with Congenital Heart Diseases in Offspring: An Updated Meta-Analysis of Observational Studies.” Medicine (Baltimore), vol. 100, no. 9, 2021. doi:10.1097/MD.0000000000024899.
Sass, Laura, et al. “Fever in Pregnancy and the Risk of Congenital Malformations: A Cohort Study.” BMC Pregnancy and Childbirth, vol. 17, no. 1, 2017, p. 413.
Jiang, H. Y., et al. “Maternal Infection During Pregnancy and Risk of Autism Spectrum Disorders: A Systematic Review and Meta-Analysis.” Brain, Behavior, and Immunity, vol. 58, 2016, pp. 165-172. doi:10.1016/j.bbi.2016.06.005.
Werler, Martha M., et al. “Maternal Medication Use and Risks of Gastroschisis and Small Intestinal Atresia.” American Journal of Epidemiology, vol. 155, no. 1, 2002, pp. 26-31.
MotherToBaby. “Fever / Hyperthermia.” Fact Sheets, Organization of Teratology Information Specialists (OTIS), Feb. 2023. https://www.ncbi.nlm.nih.gov/books/NBK582757/.

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