Smells like I’m on my period

I’m 37w1d and I’ve noticed that I smell like I’m having a period. No discharge or anything like that. It doesn’t smell bad, just like I’m having a heavy period and wearing a pad. I’ve had BV and yeast infections before so I know it isn’t that.

I did have sex last night and the night before, so maybe it’s sperm? But it’s never made it smell like a period.

Has anyone else experienced this?