Norethindrone
"The first time I used it after my first pregnancy while breastfeeding, it was great. It even extended my cycle and I'd often have a lighter shorter  period every other month. But after my second pregnancy it seems to be doing the oposite! I've already had my period 3 times this month! Don't know what caused it to have a drastic change in side effects for me. Other than, the unpredictable cycle, I've had no other problems with it."