When Should a Baby Be Born?

Dr. Jones: When should a baby be born? It's sort of a Goldilocks problem isn't it? When is too early? When is too late? And when is just right? This is Dr Kirtly Jones from the Department of Obstetrics and Gynecology at University of Utah Health Care. Today we are talking about when should babies be born, on The Scope.

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Dr. Jones: So how do you know when an apple is ripe? Just right. By color? By size? By season? Do you pull it off the tree? But if you're wrong you can't put it back. Do you wait till it falls until the tree thinks it's ripe? Well then it might get bruised. So is it the number of days? How do you calculate them? When is too early? When is too late? What about babies? When do we know that the baby is ripe?

Today we're talking with Dr. Erin Clark a perintologist, that's someone who specializes in high risk pregnancy, about when is the baby just right. Welcome to The Scope Dr. Clark.

Dr. Clark: Thanks for having me.

Dr. Jones: So how do we know when a baby is ripe? Is it 40 weeks? Is it nine months exactly? Is it certain amount of days? And how do we get that number?

Dr. Clark: The formal definition of when a woman is due is 40 weeks from the first day of her last menstrual period. We know generally that that's the date because that's around the time when most people spontaneously go into labor. We have great respect for when Mother Nature does it right. Certainly Mother Nature doesn't always get it right and outcomes for moms and babies are not always good. Ten percent of babies in the United States are born too early, but most of the time delivery occurs about that 40 week mark.

Dr. Jones: So when is it too late?

Dr. Clark: It's a complicated question but if we look at outcomes for moms and outcomes for babies, a variety of outcomes. Stillbirth, c-section rate, the ability of a baby to breath and do well after delivery. If we look at all of those outcomes, the lowest risk time, the sweet spot, so to speak, that perfectly right apple seems to happen at 39 weeks give or take a week or so. So between 39 and 40 weeks appears to be the lowest risk time.

There's very good data that suggest if we go before 39 weeks electively, sometimes there's a very good medical reason to do that, but before 39 weeks babies have more difficulties after birth. They can have difficulty regulating their temperature, they can difficulty with eating, they can have difficulty with breathing. We know that in a well dated pregnancy at 39 weeks or beyond, babies do really well.

There is a point though at which pregnancies can go too far and it's a gradual increase in risk that happens after the due date which is at 40 weeks. So again that sweet spot appears to be 39 to 40. In general we try to get women delivered about a week past their due date at the latest because those risks start to climb.

Dr. Jones: So what are those risks?

Dr. Clark: For babies there is a risk of stillbirth that climbs over time. That's the biggest and scariest risk because a baby who has a stillbirth does not survive to have any of the other outcomes. But there's also a high rate of c-section because the placenta while it's miraculously marvelous organ, it has a life span. And after the due date it starts to baby and labor is a stressful process for babies and if that organ is not functioning optimally, we see signs in labor by watching the baby's heart rate that the baby is just not getting the oxygen and nutrients that are necessary and so the c-section rate is higher.

There is also some other risks that are higher for moms. The rate of hemorrhaging associated with delivery, the rate of having a baby that doesn't fit because of size. Those things go up over time too. So when we look at those myriad of complications, all of them are at their lowest risk at that 39 to 40 week mark.

Dr. Jones: But it's not always so easy. So if you decide 39 to 40 is a good number, how do we get the baby out then?

Dr. Clark: Maybe this is the apple and the worm analogy.

Dr. Jones: Okay.

Dr. Clark: There's very good data, 39 to 40 weeks baby is ready to come out beyond 39. But the other question that you're getting at is when is mom ready? Sometimes the two are not in sync. But what has been shown is that if you don't induce labor in a timely fashion after the due date has passed, actually the c-section rate goes up and not down. The cervix is like a fist, before labor starts, it's hard, it's somewhat unyielding and as preparations for labor happens it gets softer.

Dr. Jones: Well that's a good thing because we want to get the baby in for those 40 weeks or 39.

Dr. Clark: Correct. It's appropriately unyielding. But as preparations for labor made it gets soft, it get thinner, it starts to open. These are signs that we like to see as women get ready for labor and even in a patient who has a cervix who's not quite ready, if they're going past their due date especially a week or more, we know that their lowest risk are to induce labor rather than wait.

There's the other question though of when is the earliest that's safe to induce labor without a medical indication? And 39 weeks appears to be the earliest based on what we talked about as far as risk for baby go up if we go any sooner than that. In a woman whose had babies before who has a cervix that is soft and ready for labor and who is known solidly to be at least 39 weeks gestation, induction of labor electively is felt to be a very reasonably medically safe practice.

What is less well known and what we need research is what about the woman who has not had babies before? There's many advocates, experts across the nation who say because of this data that suggest that 39 weeks is that lowest risk spot, maybe that should be a policy. Maybe we should induce everybody between 39 and 40 weeks because we know we would see less stillbirths, we would see less pregnancy complications like preeclampsia. Maybe that's the right approach.

Clearly there's a lot of push back saying Mother Nature, Mother Nature. We should let most of these labors go on until there's an indication to intervene. But it's still a big question, and it won't be answered until we take a group of women who have not had a baby before and randomly assign them to either watchful waiting. Seeing if they go into labor on their own and intervening if there's a medical reason. Or another group of women where when they hit 39 weeks and we say it's time to have a baby and regardless of what your cervix says as far as readiness, we're going to give you the medications that will stimulate labor.

Dr. Jones: So this is study that's ongoing?

Dr. Clark: This is a current study. This is a national multi-site study. In Utah we have several participating sites one of which is The University of Utah, one of which is Intermountain Medical Center in Murray, LDS Hospital in Salt Lake City, Utah Valley Regional Hospital in Provo, and McKay-Dee Hospital in Ogden. We are trying to enroll 6,000 women across the nation for participation in the study.

Dr. Jones: Are ladies anxious to sign up? I am assuming randomization is 50/50.

Dr. Clark: It's 50/50.

Dr. Jones: When they randomized and they get not the arm they wanted, are they doing okay?

Dr. Clark: Yeah, we have two camps of women. One is very much wanting spontaneous labor to happen. They want that story of my water broke in bed one cold winter night. They can tell over and over again to this child forever. They want that natural course. And they're not interested in participating and that is totally fine.

There's another group of women who says for logistical reasons this would be a really nice thing to have a time delivery about a week before my due date and there's some enthusiasm there for participation. Remember this is a group of women who are not eligible otherwise to have an elective induction a week early who, yes, are very interested in participating. The ones who are very much often want to be in that induction of labor arm and there are sometimes tears when they randomize the other way but again it gives them a chance at that earlier intervention whereby they wouldn't otherwise. So for some women it is a very nice option.

Dr. Jones: To round up, it sounds like you want your baby just right and somewhere between 39 and 40 weeks is, we think for babies, just right. Up to 41 is kind of practice now but maybe sooner is better. People, if they're having their first baby and want to contribute and they deliver at those places can sign up and hopefully you'll have a perfect little apple for Thanksgiving.

Dr. Clark: Right. That's the goal.

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