The critical period for development, when exposure to disease prenatally can have the most devastating effects of growth, is

during the first 3 months.

It's 3 months

Explanation:

Although people tend to feel well at this stage (3months) it is important to remember that the virus/bacteria is still active. As it continues to reproduce and infect new cells also damages a person's immune system at this period of time.

answer; top-down processing;