Teratogen Update: Fever in Pregnancy.

Area of Science:

• Reproductive Medicine
• Developmental Biology
• Teratology

Background:

• Maternal fever (hyperthermia) during pregnancy is common.
• Emerging evidence links transient maternal hyperthermia to adverse fetal outcomes.

Purpose of the Study:

• To review animal and human studies on maternal hyperthermia and pregnancy outcomes.
• Examined associations with structural birth defects, neurodevelopmental disorders, fetal growth restriction, and pregnancy loss.

Main Methods:

• Conducted a narrative review of published literature.
• Included experimental animal models and observational human studies on maternal hyperthermia and pregnancy outcomes.

Main Results:

• Teratogenic effects of maternal hyperthermia are dose- and timing-dependent, with highest risk in the first trimester.
• Associated outcomes include neural tube defects, craniofacial anomalies, congenital heart defects, neurodevelopmental disorders, fetal growth restriction, and pregnancy loss.
• Potential mechanisms involve heat-induced cellular stress and maternal immune activation; folic acid and antipyretics may reduce risk.

Conclusions:

• Consistent findings across models suggest a biologically plausible teratogenic effect of maternal fever.
• Limitations include reliance on observational data, difficulty in temperature measurement, exposure assessment variability, and confounding factors.
• Maternal fever is a potentially modifiable risk factor; preconception folic acid and fever management are supported preventative strategies.