Why do young women with PCOS have irregular menstrual cycles?
Having PCOS means that a young woman’s ovaries are not getting the right hormonal signals from the pituitary gland. Without these signals they will not ovulate regularly. Their periods may be irregular or absent. • Normally the menstrual cycle starts when the brain sends LH and FSH to the ovaries. A big surge of LH is the signal that tells the ovaries to ovulate, or release a ripe egg. • The egg travels down the fallopian tube and into the uterus. Progesterone from the ovary tells the lining of the uterus to thicken. • If the egg isn’t fertilized, the lining of the uterus is shed and the menstrual period will start. • After the menstrual period, the cycle begins all over again. The PCOS cycle shows where the menstrual cycle stops just before ovulation. As a result, girls with PCOS may ovulate occasionally or not at all so periods may be too close together or more usually, too far apart. Some girls may not get a period at all. • With PCOS, LH levels are often high when the menstrual cyc
