Women's Health Community

Dear An: Thanks for waiting for a reply. If you had your normal "pill period" on your birth control pills the following is my best GUESS.

Breakthrough bleeding (BTB) can be a common side effect of most types of hormonal birth control (eg pills/patch/ring/shot/Mirena IUD). Among birth control pill users BTB frequently occurs after a missed or late pill. In your case it sounds like you are taking your pills at about the same time daily. More remotely, BTB in a pill user can arise if she has gotten a chlamydia infection. Yet, if you both are monogamous this is not going to apply.

When a woman uses hormonal birth control it can make the lining of the uterus more unstable--so it is easier to have some of it begin to shed. Sometimes the lining is less stable because the hormones make the lining much thinner (actually this is good as a thin lining is a healthy lining).A very thin lining is more common in longer term BCP users. Sometimes the lining is unstable because the hormones can make parts of the lining out of synch. This is more common during the initial months of BCP use.

Usually BTB is scant and thus the small amounts of blood tend to be dark brownish/black (like motor oil sludge). This is because the blood has more contact with the oxygen in the air. It is not usually the sign of a worrisome condition.

Bottom line, BTB on hormonal methods of birth control is a nuisance side effect. The protection from pregnancy is still in effect. If your poor cycle control persists you should return to your GYN or clinic. Often a change in the brand, or formula, of birth control pill will fix the problem.

Yours,
Jane