In the days to weeks leading up to delivery, your body is doing prep work, and you may not even know that it's happening. You might not have any contractions at all, you go to your doctor's appointment, and they tell you that you're dilated and effaced a little bit, and you're wondering, "How could this have happened if I wasn't contracting?" You're body will start to release hormones called prostaglandins that act on the cervix and ripen it. That's the actual medical term we use. It can ripen just like a fruit. A fruit can be ripe or not ripe, and a cervix can be ripe or not ripe. A cervix that's not ripe will be way far back in your pelvis. It's pretty hard for us to find when we're trying to check your cervix. Then as it ripens, it begins to move forward. Another quality of a ripened cervix is it's consistency. It can be soft, medium or hard. So when it's ripened, it's actually soft. Another element to the ripening process is the 'thick and thin' of the cervix. On the day you got pregnant, your cervix was pretty thick - almost the thickness of someone's finger.
At the beginning of the 3rd trimester, it might start to thin slightly, but we don't want it to thin too much until later on in the process. But again, in the days to weeks leading up to delivery, it will start to thin, and at that point, it's a good thing. Once you're approaching your due date, and your cervix has become softened, it's moved forward in your pelvis, it's begun to thin out, then it will respond well if your brain starts to release oxytocin, which is a hormone that tells your uterus to contract. Once you have regular and intense contractions, those can cause your cervix to dilate if it's ripened beforehand.
I had a friend that said, after she had her baby, "I was in labor for 5 days and they sent me home 5 times." She was frustrated. The fact of the matter is, she wasn't actually in labor until the hours leading up to the delivery of her baby, when her cervix was actually changing, or dilating. In those 4+ days leading up to the point where her cervix started changing, her cervix was probably in the process of ripening. If you have a lot of regular and intense contractions, a cervix that's not ripe will do nothing. You can still hurt a lot and feel like you're dilating, and nothing is happening. So it's actually really normal, especially for first-time moms who have never experienced labor before, to be sent home at least once before they have their baby.
So maybe you go to your doctor's appointment at 38 weeks, and he tells you you're 1.5 cm, you're 60% effaced, the baby is at -2 station, and you have no idea what all of that means. Basically, what you want to know is if you're going to have a baby that week or not. It's really hard to tell. Even if someone has a cervix that isn't ripe on a Monday, they could very well deliver in the following week before their next OB appointment. Or if someone has a very favorable cervix and they think they're going to deliver the next day, they may still stay pregnant for a week. There is no good way to predict when you're going to have your baby. The best thing you can do is watch for signs of labor, and that includes regular and intense contractions. Labor is just one of those things where "No pain, no gain" - you have to hurt to have a baby. So look for regular and intense contractions once you're 37 weeks (that's when you're full-term), and once they're 3-5 minutes apart, and you're breathing through them, and that's been going on for a couple of hours, then it's time to go to the hospital.
But there are other reasons why you would want to go in sooner, whether you're contracting or not. If you have any vaginal bleeding, if you feel like your water broke, or you're not feeling your baby move as much as you usually do, you go in, in spite of contractions or no contractions. There are a couple of things that would get you admitted to the hospital. The 1st is that your cervix is actively changing from hour to hour, which is the true definition of labor. So if you show up for contractions, the first thing we'll do is check your cervix, and then we'll watch you for an hour, cross our fingers, shut the door, tell you to work hard, come back and see what happened an hour later. If you dilated, then your doctor will say, "Yep, she's in labor. She gets to stay." If your cervix hasn't changed and everything else looks good, that's when you would go home.
Your 2nd admit ticket is that your water has broken, whether you're contracting or not. So again, this is a reason, in and of itself, to go to the hospital, because the amniotic sac acts as a barrier between the inside and outside world, and once your water has broken, there's a risk for infection, so you need to go into the hospital and get checked out. The 3rd and 4th reasons for admission are that something is wrong with you or the baby, so stick with the first two. I hope the best for you.