I'm 38 weeks pregnant. placenta is now clear of cervix, but close enough that if i dilate, i'll most likely bleed. is orgasm (w/o penetration) safe?

May be: You are near term with a risk of bleeding. I would recommend holding off on sexual activity till after delivery.

Asking for trouble: With a low-lying placenta, labor forces the head against the placenta; this usually tamponades serious bleeding until delivery. Orgasm causes some contractions of the uterus, which may result in bleeding, but once contractions stop, no longer have the head pressing against the placenta to stop bleeding.