What happens if a female recive her period every 2/3 months ?

It's OK: It is not dangerous to have infrequent periods, and a number of birth control pills now offer this option. If you're not on the pill, fewer periods means fewer opportunities to get pregnant, most likely, as ovulation usually occurs within 10-14 days from the first day of menstrual flow. Even with irregular periods, that interval is fairly consistent. You usually have only one ovulation per cycle.