Women's Health Community

Dear Camom: Wow, very regular cycles for 23 years; this is an achievement! The most common reason for a menstrual pattern like you have described 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. The good news is that you have enough estrogen to make a lining that does shed.

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—your missed period. Alternatively the built up lining can begin to shed just off the top layer producing erratic/prolonged spotting

Causes for not ovulating are multifold: thyroid problems, pituitary problems, ovarian cysts, physical stressors (eg sudden increases in exercise, crash dieting), emotional stressors (problems with spouse/children or finances), increased body weight, anorexia, rotating shifts at work, etc.

Lastly, everything I have just shared with you pertains to women who are NOT using a form of hormonal birth control. If you are using an oral contraceptive, or DepoProvera, or other hormonal contraceptive you may miss a period (s) for an entirely different reason. Once pregnancy has been "ruled out" (because even reliable methods fail) one can usually assume that the missed period is "normal" or "OK". Unlike the scenarios discussed above, women on hormonal contraception have both estrogen and progesterone available. If the synthetic progesterone is dominant, it can artificially make the uterine lining very thin. So the woman misses her "Pill period" or it is very much lighter than normal. Of note, if you are on a form of hormonal contraception, and you miss a period (s), you will not have a uterine lining build up.

Bottom line, the most important thing is to completely rule out pregnancy. Given that your cycles have always been super regular one would hope that your own natural pattern will return next month. If not, or if you develop pelvic pain (eg ovarian cyst), see your OB/GYN or local family planning clinic.

Yours,
Jane