A girl's first and second periods can usually be separated by up to 6 months. A female might also wait up to four months between her second and third cycles. Normal irregular periods might last up to two years. Menstrual periods can be disrupted by stress. By talking about it, you may try to assist your daughter deal with her stress. Stress can cause the body to produce more of the hormone cortisol which in turn can lead to premature maturation of the brain and other organs including the uterus. This can occur before all the reproductive organs are fully developed and affect a woman's ability to have children. The average length of time that a woman can go without a period is around 3-5 years but some can live as long as 10 years without one. The reason why so many women report missing their periods over such a long period is because they cannot see them coming. A lot of times when a woman doesn't have her period for three years it is because she is pregnant. She just needs to get tested to make sure everything is okay then get back on track with her cycles. If you aren't having your period and it has been more than three years then see your doctor immediately.