What effect does repeated, regular stimulus have on infants?

They can be born with a various type of birth defects 

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.

Answera tightly sealed house with an unvented water heater;