Chart your basal temperature (temp first thing in the a.m. before you even get out of bed). The day that it spikes is supposed to be the day that you ovulate. It will stay elevated for a few days during your period then it should even out again. While you are charting your temperature, also chart the consistency of your mucus (yes, I said MUCUS) -the slimy stuff down below! It will go from thick/white to slimy/clear on the days leading up to ovulation. When it is the thinnest and most stringy in your fingers, that's the day to have sex if you want to increase your chances of getting pregnant.
at 12:35 AM on Jul. 3, 2008