Oh come on... I don't say things which I ain't sure of...
Read this 
Yes, if it's in the first days of your period. And also if you're
100 percent guaranteed it's your period you're seeing. It's
possible to have a delay in ovulation and subsequent "break
through" bleeding; also, the closer to the end of your period you
are, the closer to ovulating you are.
The most fertile times are six days before ovulation, so if your
period trails on to day seven or eight, having intercourse on those
later days may be approaching the danger zone.
It's by a board certified obstetrician-gynecologist ....
Btw intercourse means sex .. this is for those who are clueless
