Having sex on your period or whilst your partner is, and having an orgasm actually relieves cramps because they’re naturally pain relieving. Not only that but having sex on your period can also shorten yours or your partners period. Less bleeding- yay!
The amount of blood released by a woman on her period is only around 30-40 ml over a few days. So it isn't the bloodbath you may imagine. If it is only 30-40 ml per menstruation, that really is not much per minute. Hence the amount of blood released during sex will not be much at all. If you are really that worried about it being messy though, you can always put down a blanket or towel. It will also make clean-up easier.
Some women can get more aroused during sex and there can be heightened arousal, therefore sex will be more enjoyable. Many women claim to be more turned on during menstruation, which means more pleasure when stimulated.
Despite what some may believe, period blood is not harmful to a guys penis. Blood is not an irritant and nothing bad will happen if you have sex on your period. If you do not like the idea of it getting everywhere though a condom can be worn or a flexible tampon- DO NOT use a normal tampon.
As mother nature has provided you with blood coming out of a vagina, you will not need lubricant if you usually use it. Although you can still get pregnant and potentially get STI’s whilst having sex on your period so please use protection.