Can High Fever During Pregnancy Cause Developmental Disorders?
When a pregnant woman develops a fever, it’s natural to worry about how it might affect her developing baby. The relationship between maternal fever and potential developmental problems is an important health topic that deserves clear, straightforward explanation.
The most significant concern with high fever during pregnancy involves the first trimester, which is the critical period when a baby’s major organs and systems are forming. Any fever of 38.9 degrees Celsius (102 degrees Fahrenheit) or higher that lasts for 24 hours or longer during this early stage of pregnancy significantly increases the risk of neural tube defects and other birth defects. Research shows that women who experience such high fevers during the first trimester have a 1.8-fold increased risk of major structural malformations compared to women who don’t have fevers.
The specific birth defects associated with first-trimester fever exposure include neural tube defects, which show a 1.5 to nearly 3-fold increased risk. Congenital heart defects and oral clefts also show similar increased risks. In some cases, high fevers have been linked to stillbirth, with studies showing increased frequency in pregnancies with severe fever.
Beyond birth defects, there has been growing research interest in the connection between maternal fever during pregnancy and autism spectrum disorder. Studies have found that recurrent fevers during pregnancy can increase the risk of autism by up to 300 percent, particularly in pregnant patients with severe or prolonged infections. However, it’s important to understand that maternal fever itself appears to be the risk factor, not the treatment used to manage it.
This distinction matters greatly. Some research has suggested a link between acetaminophen (Tylenol) use during pregnancy and autism, but high-quality studies have shown that the actual explanation lies in the mother’s health status. Mothers with a history of pain disorders, high fevers, health problems, or migraines are slightly more likely to have a child diagnosed with autism and are also more likely to take acetaminophen. The fever and underlying infection, not the medication, appear to be the true concern.
Fever can also pose risks during the second and third trimesters. A fever above 39 degrees Celsius (102.2 degrees Fahrenheit) during labor increases the rate of neonatal encephalopathy to 4.4 percent compared to 1.1 percent with temperatures between 38 and 39 degrees Celsius. Additionally, fever in the second or third trimester can trigger contractions, potentially inducing premature labor.
The underlying cause of the fever matters as well. Fever itself doesn’t directly harm the baby, but the infection causing the fever may put the baby at risk. Various infections can cause fever during pregnancy, including the flu, urinary tract infections, COVID-19, pneumonia, and foodborne illness. Some infections like cytomegalovirus can pass through the placenta and cause problems such as microcephaly and deafness in the baby.
Medical professionals recommend that pregnant women with fevers seek evaluation to identify the underlying cause and determine if treatment is needed. According to the Society for Maternal-Fetal Medicine, an untreated fever, especially in the first trimester, increases the risk of miscarriage, premature birth, and birth defects. This is why obstetricians typically advise their pregnant patients to use acetaminophen to control fever, as it is considered the safest over-the-counter medication available during pregnancy.
The key takeaway is that high fever during pregnancy, particularly in the first trimester, does warrant medical attention and treatment. The risks associated with untreated fever appear to outweigh the risks of using acetaminophen to manage it. Any pregnant woman who develops a fever should contact her healthcare provider for proper evaluation and guidance on appropriate treatment options.
Sources
https://www.tuasaude.com/en/fever-while-pregnant/
https://www.infectiousdiseaseadvisor.com/features/infections-during-pregnancy/
