Birth control

Not one pill (unless they are the last week which are just sugar pills). The anterior pituitary glad produces hormones that trigger the ovarian release of progesterone and estrogen. When you get a spike in estrogen (usually caused by a drop in progesterone) ovulation is triggered. Maintaining high levels of progesterone is what happens when you are pregnant which is what MOST pills replicate. Even missing one pill can cause the drop in progesterone and spike in estrogen that causes ovulation. Since sperm can live for 5 days and your eggs can live for 2, that means missing even one pill can be bad news.

On the up side, there are SO MANY NEW METHODS if you do have a hard time remembering. The patch, the OrthaOva ring, the IUD (although most doctors will only let you have that if you've had a baby). So good luck!