| No, it’s not unhealthy for a woman to use combined hormone contraceptives to put off menstruation for months or years. The lining of the uterus does not thicken in these circumstances. In fact, over time, it becomes very thin, which is why some women stop having periods altogether after being on 28-day combined hormonal contraception for several months or years.
The progestins in combined methods prevent the lining from thickening. Unchecked, unhealthy thickening of the uterus could be caused by estrogen when no progestins are present to keep that from happening. But because estrogen alone cannot prevent pregnancy, there are no estrogen-only birth control methods.
So, it is fine, and not unhealthy, for a woman on a combined hormonal contraceptive to not have periods. | 
