Muscle spasms/pulse feeling pelvic areas?!

Cassandra • 26 years old. First pregnancy and I can't wait till Jan. 19th!
I've started feeling something like a muscle spasm/pulse 5-10 pulses under the stomach, the center of my pelvic area about where the top of my underwear hits. Happens maybe once or twice a day usually when resting I'm 30 weeks with my first. Any ideas what this could be? Too low to be kicks I'm sure.