Paragard

I have recently just gotten the paragard iud and have been having unprotected sex with my fiancé. I have let him cum inside me several times, including during my fertile window this month. I know that the iud is over 99% effective, but I was wondering if there's anyone on here who had gotten pregnant with it in? I guess (even though I have it) I am still a little skeptical of how well it works with no hormones. Is it a bad idea to let your significant other cum inside you still? Or should you be able to trust in the iud? Thoughts, comments?