Poss pregn, new job--insurance ques, HELP!!?

My sister just got a new job teaching high school. She just got hired. However, she does not have their insurance yet...still has to attend the new hire meeting and THEN make appt for insurance meeting. She just found out that she might be pregnant (yay happy!) BUT is worried that her pregnancy will not be covered by her new insurance (esp since probably ?? won't kick in until later b/c new year begins later in August). She doesn't have insurance now. Is pregnancy considered a "pre-existing" condition? Will she and baby-to-be be covered? Please help! We greatly appreciate it you guys!!