Less Frequent Menstrual Periods
The functioning of the thyroid can have an effect on menstruation. For instance, an underactive can be the reason for a heavier than normal flow and more sever cramps than usual. On the other hand, an overactive thyroid can lead to periods that are shorter and lighter than usual and are spaced farther apart than normal. In these instances, there is a decreased chance of pregnancy as these menstrual periods are much less regular (and also because it can lead to a decreased interest in sex).
