Peri-menopause is the time period before menopause when hormonal fluctuations are common. Peri-menopause can last as long as 10 years; during this time, menstrual cycles may change in length, frequency, duration and intensity. During peri-menopause, ovulation may not occur every month; according to Gerson Weiss, M.D., about 20 percent of all women will have cycles where ovulation does not occur (anovulatory cycles) in addition to ovulatory cycles.
Long Menstrual Cycles
During peri-menopause, estrogen is still being produced by the ovary, but in varying amounts; some months, estrogen may not be high enough to stimulate egg production. Menstrual cycles where estrogen levels are low may be longer than normal, because some estrogen is being produced, even though no egg is being matured; the uterine lining just keeps thickening. Eventually, the lining becomes so thick it starts to slough off, creating what seems to be a short, irregular period with spotting that may start and stop.
Short Menstrual Cycles
According to Dr. Aniruddha Malpani, menstrual cycles shorter than 21 days are often associated with a lack of ovulation. Shortened cycles can be caused by a defect in egg production or egg release in anovulatory cycles, according to Dr. Weiss.
Estrogen levels, according to Dr. Jerilynn Prior, are often higher than normal during peri-menopause; she states that anovulatory cycles combined with high estrogen levels may contribute to heavy menstrual flow in peri-menopause. Dr. Prior quotes A. Oldenhave of the Leiden University in the Netherlands as saying that heavy periods, or menorrhagia, occurred in more than 20 percent of anovulatory cycles in peri-menopause.
Endometrial dysplasia is caused by too much estrogen and not enough progesterone. Because estrogen is being produced in anovulatory cycles, the uterine lining thickens. But progesterone is lacking, because progesterone is produced by the corpus luteum, the leftover part of the ruptured follicle after ovulation. If no egg is ovulated, there's no progesterone produced. Endometrial hyperplasia increases the chance of developing uterine cancer, according to the American Congress of Obstetricians and Gynecologists (ACOG).