Constant dull ache/period feeling- early labour?

Victoria

Hi there, I’m 38+1 and feel that really heavy feeling/ dull ache that you get when you have your period. It’s not cramps specifically as doesn’t come and go, just that constant period pressure feeling. Anyone have any experience if this is early labour or just a sign the baby is engaged (I’ve had very bad pelvic pain the last few days so assume his head is down low!)