are these contractions

I was just sitting here and I felt a pain in my right lower stomach, the only way I can explain is when you stretch and you pull/stretch a muscle in your lower stomach and it hurts/cramps for a little while then wears off. I've felt like I'm on my period all day but it wears off and this has been going on for more than 12 hours. I'm just wondering if it's the start because I'm 39 weeks and been having pains for a while