Women's Health Community

Dear Anon: It is less likely that you are pregnant, but if you are having pregnancy symptoms that should be ruled out first. If the test is negative, then my best GUESS is breakthrough bleeding (BTB).

Alas, 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 careful to take pills at 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). If the lining gets very thin a woman may not have enough lining to even make a flow. This may be what happened with your Nortrel pills. Sometimes the lining is unstable because the hormones can make parts of the lining out of synch.

The Sprintec has a different type of synthetic progesterone than Nortrel. That can be enough to change the side effect and/or bleeding profiles.

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. Some women will have perfect cycle control on almost any pill--others may have to try several brands to find the right one for them.

Yours,
Jane