Understanding the Perimenopause

Abstract

The perimenopause is usually defined as the time between when a woman notices a change in her menstrual function and the time at which she is amenorrheic for a year, hence, menopausal [1]. The usual beginning of the perimenopause is in the mid-to-late forties, at an age when reproductive function has usually ended. It is a relatively rare event that a woman in her mid-forties will become pregnant with her own gametes even with medical assistance [2]. Starting in her thirties, fertility decreases as a woman ages. This decrease in fecundity is not accompanied by any physical alteration that a woman could recognize. While there is a slight but measurable fall in fecundity, starting from age 30 relative to younger ages, at age 38 a steeper fecundity decline begins [3]. This decline increases through the early forties. By age 45, naturally occurring pregnancy is a rare event. By the early-to-mid forties the spontaneous miscarriage rate increases to over 50% [4]. There is a concomitant increase in karyotypic abnormalities. To view the changes a different way, a couple in their twenties having regular coitus has a greater than 20% chance of pregnancy in a given cycle. At age 40, this chance decreases to less than 5%. The most common perimenopausal event that women notice is a change in menstrual cycle frequency, which includes somewhat shorter cycles or occasionally missed or longer cycles. The changes in cycle length are the defining events identifying the start of the perimenopause. There may also be a change in the character of the bleeding. In addition, many women specifically complain of breast discomfort or even enlargement during this time period. It is well known that a woman is born with all the oocytes she will ever have. From birth through menopause these eggs are gradually lost, mostly through atresia, until several years after