Obs will normally do it if you're dialated and they can reach your cervix around your 39wks if you want to induce labor naturally; however, it doesn't always work. 2 years ago I had mine done at 39 weeks around 11am by 2:30 am I was having contractions and went into labor. But, I am pregnant again 39 weeks (on 03/08/17) my OB did it again and this time it didn't work
I got mine done at 37wks at 2cm dilated now I'm 37.2 and I lost my mucus plug today
Well, it IS supposed to spur your cervix to open. I had contractions after mine . . . but not the baby until 2 weeks later. So, it doesn't necessarily mean you'll go into labor but you may. If you don't want it, tell your doc. they probably think they are helping you out as most women are ready to get it over with at 39 weeks. Let us know how it goes and what you decide, okay?