Dear MrsRichs: The most common reason for a menstrual pattern like you have described (if you are not using hormonal birth control) is not having an ovulation every month. In a normal cycle, estrogen is produced all month. Estrogen is responsible for building up the lining of your uterus so you have something to shed each month.
In a normal cycle, progesterone production increases following ovulation and release of an egg.. Progesterone "stabilizes" the uterine lining in preparation for a possible implantation of a new pregnancy. If you are not pregnant that month the levels of estrogen and progesterone fall, triggering the release of the uterine lining—your period.
So, if you do not ovulate, the estrogen build up of the lining continues, but without the usual ovulation associated progesterone. Thus, the hormone levels don't decline, and the lining stays up inside the uterus—often as a missed/late period. Alternatively, the built up lining can begin to shed on its own creating erratic bleeding patterns which are usually "too-light" or super heavy and prolonged.
There can be many cause for missed ovulations: low thyroid , pituitary problems, ovarian cysts, physical stressors (eg sudden increases in exercise, crash dieting), emotional stressors (problems with partners, finances), increased body weight, anorexia, rotating shifts at work, etc. Age can be a factor as well. Ovulations become more erratic as we move into our 40's--especially the mid to late 40's.
Some other possible causes of sudden onset unscheduled bleeding can include: undetected pregnancy, use of a hormonal form of birth control causing breakthrough bleeding, or a new infection with gonorrhea or chlamydia. If you have pelvic pain (eg ovarian cyst or infection) you should see a GYN promptly. If this erratic bleeding persists you should see your GYN or even the local county family planning clinic.
You are encouraged to report negative side effects of prescription drugs to the FDA. Visit the FDA MedWatch website or call 1-800-FDA-1088.
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