Having an orgasm can cause contractions too just B H I had them everytime from 20 wks on with my son and had him at 39wks1d
You're not likely to induce labor that early with sex. It does cause BH which are not harmful. If you have O it will make the BH more intense as well. I was having sex 1-3 times/day for over 2 weeks still ended up induced and I was dilated/thinned.
They do say that sperm brings labour on (but you do have to do it quite alot)..personally i sware by it as it worked in my last pregnancy but i will make my husband pull out at the mo as i am only 29weeks and do not want my baby early,so you could try that but you do need yo have quite alot of sex to induce labour.
Sperm can cause your cervix to ripen and or thin out. I'm 36 weeks and my doctor suggested as much sex as I could stand (I've had all previous pregnancies induced on some level so we're hoping I go on my own this time). At 27 weeks I wouldn't be concerned though. It's normal to have braxton hicks and you may just want to mention it. I wouldn't worry though. Those are braxton hicks and their just your bodies way of preparing for labor.