Relatively speaking this is true, key word relative. Fertilization and implantation can still occur even during your actual period so in actuality there is no real "safe window"....only "biologically speaking conception is not favorable after your period".Supposedly, there is a "safe window" a few days after your period, where the risk of getting pregnant is very slim.
This is called anecdotal evidence..."I did it, nothing happened, therefore there is a safe time". Obviously this is not true. Ask any woman who conceived when they thought they were in the clear and safe.he said that he's had sex with a woman before during the "safe window" and nothing ever happened
If you do not want to be pregnant then unprotected sex is not the way to go no matter how many buts or pleases are said.