Thanks for your question.
First, although no one has properly tracked it, spotting or “breakthrough” type minor bleeding before the full flow starts is not uncommon. To the best of my knowledge it doesn’t mean anything harmful. It’s just a risk for stained panties and costly in panty-liners!
I would guess we saw spotting before proper flow in about ten percent of 66 ovulatory women who kept menstrual cycle records for a year (1 [1]). Those women who had spotting before flow tended to see it in many cycles. We classified the first day of spotting as the start of flow if there were no days without spotting before the full period began.
What causes it? That’s still a mystery. We’re currently examining flow in those 66 ovulatory women and will be asking whether spotting before flow is more likely to occur in women who have less progesterone and shorter times from ovulation until the next period. I do know that spotting increased in young women who began very intense exercise training and lost weight (2 [1]).
What should you do about spotting before flow? For sure, I don’t recommend using oral or other hormonal contraceptives. I would start keeping the daily Menstrual Cycle Diary [2] and, if you are earnest in seeing what’s going on, also track your basal temperature. If you are having a luteal length less than 10 days long or not ovulation, for the spotting—and for other reasons like helping bone (3 [1]) and preventing endometrial cancer—I’d ask your doctor for a prescription for Cyclic Progesterone Therapy [3]. You could also use medroxyprogesterone for 14 days each cycle. This should take away the spotting. If not, keep taking the progesterone or medroxyprogesterone until the next full flow starts.
Hope this is helpful to you.
Reference List
1. Prior JC, Vigna YM, Schechter MT, Burgess AE. Spinal bone loss and ovulatory disturbances. N Engl J Med 1990;323:1221-7.
2. Bullen BA, Skrinar GS, Beitins IZ, von Mering G, Turnbull BA, McArthur JW. Induction of menstrual disorders by strenuous exercise in untrained women. N Engl J Med 1985;312:1349-53.
3. Prior JC, Vigna YM, Barr SI, Rexworthy C, Lentle BC. Cyclic medroxyprogesterone treatment increases bone density: a controlled trial in active women with menstrual cycle disturbances. Am.J.Med. 1994;96:521-30.
