38w5d pregnant, menstrual like cramps?

They don't feel like Braxton Hicks contractions, and they are pretty constant, but only at night. They don't come in waves or anything, it feels exactly like mild PMS. I have no idea if I'm dilated or not, the last time I was checked was at 36 weeks, and I was completely closed. We are hoping she can wait to be born until after the 7th..is that likely, or does this sound too much like impending labor??