I want to know if its true that the 3 days after your menses you wont get pregnant even if there's sperm in the body?
If you are a women where your period comes on time every month you will usually ovulate 7-10 days after your last period. That is when you are the most fertile. They do have ovulation kits that you can get and tell you when you are ovulating. Keep in mind these tests are not 100%. There is also taking the temp., way. Take your temp and get a baseline. In the morning with your first void take your temp. And record it. Make sure you do this the same time everyday. Once your temp elevates you are going into the ovulation period.
After a period, you will have ovulation every cycle, most normal cycles are 28 days, like the moon, but that doesn't mean that you cannot get pregnant in between because sometimes ovulation is irregular, as well, sperm can survive in a woman's body for slightly over a week. So using this method for contraception not good, but often used when trying to conceive. Check body temperature, when there is an increase, or light discharge, this is often an indication of ovulation.