From the third month until birth, a developing human is called a(n) fetus newborn embryo zygote

A developing human baby is called a fetus 

The answer is epidermis

You should only go in for less than 10 minutes at a time, or avoid them altogether, especially in the early weeks. studies have shown an increased risk for birth defects in babies of women who had an elevated temperature before 7 weeks of  pregnancy.