The menstrul cycle is carried out primarily by hormones. It has to do with everything from sexual hormones to mental hormones. Acetylcholine is the primary mental hormone while estrogen is the primary female sexual hormone(just as testosterone is the primary male hormone.) If you are not extremely late (2-3 weeks) then don’t worry. A women can miss her period do to many factors; especially stress, which everyone is prone to. If you miss you’re period, even altogether for the whole month, don’t think pregnancy is the primary candidate. It takes 30 days of everything going “right” for your period to be “on schedule.” If your period is a little off schedule, or even if you miss one altogether, the majority of the time it is due to a hormonal imbalance. Only seldom is it due to pregnancy. Still, home pregnancy tests can be used as early as two weeks before a missed period.