How does a fetus handle mom's fever?

Through Mom: Difficult to know the degree to which the fetus has developed its own capacity to fight infection, and its primary defenses are those of the mother and the placental barrier between mom and baby. Fever is felt by many to be a helpful mechanism in fighting some infections. The fetus will obviously be affected by its mothers illnesses.

Passively: Most data show a fetal system remains passive & shares moms temperature (high or low). While there has been speculation on fevers affect on the fetus, it appears benign. If mom experiences an illness where virus or bacteria enter the blood, baby can be infected & effect depends on degree and stage of development (ie rubella). A newborns thermal control system begins active work within their 1st hr.