Have you watched Orgasmic Birth? I know we're talking "orgasmic pregnancy" here but it's very related. I like the way they discuss how pregnancy and birth is all part of a woman's sexuality. It's okay and perfectly normal for you to enjoy and experience the same range of sexual responses during pregnancy and birth as you do during intercourse.

Who knows how the sensations will continue... as spock moves you may find the feeling goes away rather than gets more intense. Maybe keep unpacking these feelings and release yourself to the sensation. You may be one of the lucky women who gets to orgasm during birth!

I didn't feel what you're describing (just the full on sexy dreams), but another mother from my playgroup did. We were pregnant at the same time and she talked about almost having orgasms from baby's position... I was so jealous She also almost orgasmed during birth but stifled the feeling as she didn't like her attending midwife and didn't feel comfortable enough with her in the room.