Norethindrone
"I've been on the 'mini pill' for a few years now. I'm close to 35 and I smoke so my Gyno doesn't want me on the combination pill. I have had zero bad effects from this pill, I'm a sexually active female and have never had any problems with pregnancy while on this pill. Heres the KEY, ladies - let me put it in caps so everyone can follow along - YOU HAVE TO TAKE THIS PILL AT THE SAME TIME EVERY SINGLE DAY, if you don't you will get the break through bleeding that can happen to some girls who just pop it whenever they remember - and possibly get pregnant since you're not keeping the needed level of hormones in your body to prevent pregnancy. This pill is safe and it's effective in preventing pregnancy providing you take it daily at the same time."