March 30, 20122:00 PM ET
Operator: Good afternoon ladies and gentlemen and thank you for waiting. Welcome to the NIH Call on Changing Labor Patterns. All lines have been placed on listen-only mode and the floor will be open for your questions and following the presentation. Without further adieu it is my pleasure to turn the floor over to your host Mr. Bob Bock. Mr. Bock, the floor is yours.
Bob Bock: Thank you. Welcome to the National Institutes of Health media briefing on Changing Labor Patterns. Our speakers today will be S. Katherine Laughon of the Division of Epidemiology, Statistics, and Prevention Research atthe Eunice Kennedy Shriver National Institute of Child Health and Human Development at NIH. And Ware Branch, M.D., of Intermountain Healthcare and the University of Utah, Salt Lake City. So, I will now turn it over to S. Katherine Laughon.
Katherine Laughon: Hi. Good afternoon. The definitions for normal and abnormal labor are derived from a population of women in the 1950s, however, since that time both maternal characteristics and obstetric practices have changed considerably. So, our goal was to examine the differences in labor patterns using data from a contemporary study that was sponsored by the Eunice Kennedy Shriver National Institute of Child Health and Human Development called the Consortium on Safe Labor.
This particular study involved almost 140,000 women who presented in labor for delivery and we compared them for approximately 40,000 women from the Cooperative Care Natal Project, which was another study from the late 1950s, early 1960s. Our major finding is that labor patterns are longer now than approximately 50 years ago. So, I think that’s the summary, I’ll open the floor for questions. I’m sorry, one more thing.
A couple more points. Just mathematically, we did adjust for two known characteristics of our contemporary group to contribute to increased labor duration -- both increased maternal BMI and older maternal age -- and these only accounted for part of the increase. Certainly, epidural slows down labor but there also are other obstetric characteristics that could explain why labor is long, but we don’t have a complete explanation.
We do believe that there’s a reasonable chance that some aspect of the delivery room practice is responsible for this increase and more research is needed to identify these factors. Based on findings by other researchers, women may simply need more time to deliver than they used to. If labor is proceeding slowly, a physician may opt to give the woman more time before speeding up the pace of labor with a medication called oxytocin or before intervening with a cesarean delivery. So again, more research is needed to confirm this hypothesis.
I’d actually also like to see if Dr. Branch, if you have anything additional to add?
Ware Branch: No. I think you’ve covered it very well. It would probably be good to answer questions if the media might be interested.
Bob Bock: Thank you. Operator, we’ll take questions now.
Operator: The floor is now open for questions. If you do have a question, please press the number 7 on your telephone keypad. Questions will be taken in the order they are received. If at any point your question has been answered, you may press 7 again to disable your request.
The first question comes from Nicholas Bakalar of the New York Times. Nicholas?
Nicholas Bakalar: Hi. Thanks for speaking to us. You know, what I’m wondering about is the question of Pitocin. You say that there’s been a tremendous increase in the use of Pitocin and yet labor has slowed down. I’m confused about two things: first of all about the numbers. You say that the use of Pitocin went from 12 percent in the 50s to 31 percent today but at another point you referred to it as a 19 percent increase, which doesn’t seem right. It seems like much bigger than that 19 percent increase.
Katherine Laughon: To answer your first question, you’re correct. I’m looking at table one just as the overall characteristics of the cohort and in this DPP 12 percent of women received oxytocin versus in the CSL 31 percent. Perhaps, you might have been looking at the other tables where we broke it down specifically by parity.
Nicholas Bakalar: (inaudible). Right. Actually I was looking at the text.
Katherine Laughon: Okay.
Nicholas Bakalar: (inaudible). But never mind. (inaudible).
Katherine Laughon: Okay. But you’re right. So, oxytocin does increase labor and a lot of women in the modern cohort received oxytocin. Perhaps labor is even longer in modern obstetrics. Nonetheless, this is how modern labor currently is being practiced and labor is longer even though they’re receiving more oxytocin.
Ware Branch: I might add to that that one area of current investigation in obstetrics is whether increased maternal weight in increased BMI may be linked to less functional labor and less responsiveness to oxytocin. Those things are currently the subject of considerable investigation.
Nicholas Bakalar: Thank you.
Operator: The next question comes from Richard Knox of NPR. Richard?
Richard Knox: Yeah. Thanks very much. I have read the paper but I think that in your opening remarks you’ve kind of left us up in the air about a lot of important aspects of it. One particular detail I’m trying to get at is just how much longer hard labor has been the most recent (inaudible) versus 50 years ago. And I realized the difference for primiparas versus multiparas and people with later birth. I wonder if you could just characterize how much longer are we talking about? And then I have some other questions as well.
Katherine Laughon: Sure. For nulliparas, or first-time mothers, the median time was 2.6 longer, 2.6 hours longer in the modern cohort compared to the 1960s. And--
Richard Knox: So, the (inaudible) the total labor time would be what instead of what?
Katherine Laughon: Oh. The total labor-- If you look at the tables, if you look at table two, this is for nulliparas. If a woman came in based at-- we started at four centimeters, so the median time was 3.9 hours in the older cohort and 6.5 hours in the safe labor cohort. And then the 95th percentile to the upper limit was 18.5 hours in the older cohort compared to 24 hours in the safe labor cohort.
Richard Knox: Yeah. Thank you.
Katherine Laughon: Um-hum.
Richard Knox: So, what are you saying about the likely reasons for this big difference over this time period about what the obstetrical practice patterns that may in your view help explain it? Are you saying that there’s too much induction of labor, is it too much use of Pitocin, too liberal use of epidurals? How you parse the likely reasons for this big increase?
Katherine Laughon: Well, part of the reason is explained by an increase in epidural use. And that is known to prolong labor by approximately 40 to 90 minutes. Of course, it’s a very accepted practice to help improve pain control during labor, but it doesn’t explain all of the increase and really from this paper we’re not able to fully understand what are the reasons that are leading to longer labor time. I just think that--
Richard Knox: So--
Katherine Laughon: Sorry. Um-hum.
Richard Knox: But you do think I gather that a good part of the explanation does lie in what obstetricians are doing these days versus what they used to do.
Katherine Laughon: Well, it’s hard to know fully what is causing the increased labor time. I mean, we do mention in the comment section that certainly a large proportion of women that are pregnant these days do undergo an induction of labor. So, maybe there’s something different about the women that undergo induction versus the women that are allowed to go into spontaneous labor--
Ware Branch: Right.
Katherine Laughon: --or the same thing, the women that have pre-labor cesarean section. Maybe there’s something difference about those women and that’s why the women that elect to go into spontaneous labor-- it’s just longer. But what those differences are and what the reasons are, we just aren’t able to know from the study.
Ware Branch: It is important to recognize that our retrospective analysis included women that were felt to be in spontaneous labor. But at the same time the differences in practice patterns today versus some 50 years ago may have, as has just been mentioned, created a cohort of women who are different in their labor patterns because some have been taken out, leaving a different population, perhaps, for spontaneous labor.
Katherine Laughon: Right. We really just need more research to try to figure out what are the reasons that are leading to longer labor patterns today.
Richard Knox: I don’t want to monopolize but I wonder if I could have one other follow-up. You do say in the paper that you think these findings are likely to be controversial; why, and among whom?
Katherine Laughon: Well, I’m not sure that they’re controversial, but I think the main thing is that labor is longer and so clinicians are using definitions of what’s abnormal labor that’s based on population 50 years ago. And given the changing maternal and obstetric practice, the maternal characteristics and changing demographics, what we’re really saying is that maybe we need to revisit these definitions in a modern labor cohort.
Ware Branch: (inaudible).
Richard Knox: Well, controversial was your word.
Ware Branch: May I say something? Then I’ll get (inaudible)--
Katherine Laughon: Yes. (inaudible).
Ware Branch: I think one reason that the findings will be viewed with some controversy, has to do with the fact that we’re comparing two medical cohorts, two labor cohorts truly 50 years apart and one always worries about differences in methodology that would be hard to understand or to see as it were and so some skeptics are going to say gee, you know you really don’t know the details of what was going on 50 years ago to compare them fairly to your cohort today. So, there’s going to be that kind of discussion and it’s legitimate I think.
But some of the controversy that would derive from this kind of publication has to do with the fact that such things as epidural -- some experts would say epidural shouldn’t be challenged; it’s a wonderful pain relief mechanism. And that’s true. And so the controversy that arises is: “should practice be readdressed in some facets versus others?”
Richard Knox: Thank you.
Ware Branch: Um-hum.
Operator: The next question comes from Julie Snyder of pregnancy.org. Julie?
Julie Snyder: Hi. I have a handful of questions too, one of them you’ve sort of covered: it was when you say practice patterns what specifically you’re referring to as in the present practice patterns? And--
Katherine Laughon: Right. We didn’t have all of the practice patterns that we are able to look at in our study. The one potential one that we’ve already talked about is an epidural, which certainly previously has been shown to prolong labor, that’s pretty well known. But what other practice patterns could be contributing to these I think we just need future research to try to figure it out.
Ware Branch: Things that are hard to discover is: in the late ‘50s and early ‘60s how much did people get up out of bed during labor and walk about, for example? We now know that in modern times since in excess of 80 percent or 85 percent of patients have epidurals; once that’s in place, they’re in bed.
Julie Snyder: Um-hum. Okay. Good, yeah. That one makes sense for certain. And a little gravity it doesn’t hurt things a bit.
Ware Branch: Well, I don’t think we can say that. All I’m saying is there’s a difference--
Julie Snyder: Well, you can’t, I can, though.
Ware Branch: Okay. You can say that.
Julie Snyder: I can’t quote you as saying that for certain.
Ware Branch: No, no, you cannot.
Julie Snyder: Right. What effects do you expect these findings to have on current obstetrical practices?
Katherine Laughon: Well, I can tell you that in a previous study that’s already been published we found that especially a lot of the C-sections that were performed for failure to progress occurred before women got into the active phase of labor. We used to think that the active phase of labor is when the cervical change starts to accelerate. So on the curve you can start to see the inflection point and we used to think based on the population in the 1950s that this occurred around 3 centimeters to 4 centimeters.
And you can clearly see from the curve on this paper that it’s not so obvious when first-time mothers become active. The curve is more gradual and for multiparous it occurs around 6.5 centimeters instead of 5.5 centimeters. So, as long as the health of the mom and baby are okay in labor clinicians might be able to wait longer for women to get into active phase before intervening and doing a cesarean delivery. And the same thing as far as oxytocin use as long as a woman’s making change and is progressing at a rate that now we know is normal for modern obstetrics, then we might be able to wait before administering oxytocin as well.
Ware Branch: Yep. Indeed.
Julie Snyder: Okay. I have just one more. Is there anything specific that an expectant mom could take home from your findings?
Ware Branch: Kate?
Katherine Laughon: Yeah. I mean, I think it’s just that. I think for women that are really motivated to have a natural labor and delivery that they can feel more comfortable that if their labor is going more slowly as long as it’s within what’s been described now in the modern population that they might be able to wait longer before administering oxytocin or doing a cesarean delivery.
Ware Branch: Said in a slightly different way, well-informed patients might want to seek out practitioners who understand the apparent differences in labor patterns then versus now so that their labor can be managed in modern terms appropriately in favor of vaginal delivery when safe.
Julie Snyder: Great. Thank you.
Operator: The next question comes from Kathleen Doheny from WebMD. Kathleen, go ahead.
Kathleen Doheny: Hi. Good morning. One question has been answered so I just have two quick ones. If you’re in ideal labor range for today at what point can a long labor affect the baby or is that too individual to say?
Ware Branch: Ooh, that’s a tough one. Yeah. Kate?
Katherine Laughon: The first question is, is there an ideal labor range today?
Kathleen Doheny: Correct.
Katherine Laughon: I think this is the first step is providing the information as far as what labor looks like. One of the things I can say from looking at labor patterns is for an individual woman an average labor time is not as helpful because women follow very different labor.
Katherine Laughon: In individual and (inaudible) different labor pattern. So, I think what’s more helpful of these numbers of the 95th percentile so that you can know that an individual woman is going beyond what’s within a normal range of labor. Certainly, we provide the numbers in the table for those.
Ware Branch: That’s in Table 2 isn’t it?
Katherine Laughon: Correct. Yes.
Kathleen Doheny: Okay, got it.
Ware Branch: Okay. Yeah.
Kathleen Doheny: So, then the second question therefore is unanswerable, right? At what point can a long labor affect the baby?
Katherine Laughon: Right. We didn’t look at that specifically in this paper.
Kathleen Doheny: Um-hum. Thank you.
Ware Branch: I think that’s accurate, yes.
Operator: The next question comes from Cheryl Wetzstein of the Washington Times. Cheryl, go ahead.
Cheryl Wetzstein: Excellent. Hello. Your paper talks about the use of episiotomy and forceps as being not used as much today. I wondered if that’s correct and how would that impact any change in the labor?
Katherine Laughon: Right. That’s a really important point. If you look at Table 1 combining forceps and/or vacuum about 40 percent of women in the CVP had what we call an operative vaginal delivery versus only 6 percent in the safe labor and episiotomy 68 percent of women in the CPP versus 18 percent in the modern cohort. And so the main thing is, is that it just makes comparing, what we call the second stage which is when a woman is completely dilated and starts pushing until she delivers the baby. It makes it really hard to compare those times because most women in the 1950s and ‘60s weren’t allowed to push naturally and deliver the baby.
Cheryl Wetzstein: They had to be delivered with the forceps then huh?
Katherine Laughon: Well, I’m not sure that they had to be delivered it’s just that was the common practice back then.
Cheryl Wetzstein: Okay.
Ware Branch: It’s very difficult to point to cause-and-effect there regarding operative vaginal delivery but I think the findings would suggest that one should take another look at the use of operative vaginal delivery and training for operative vaginal delivery for its appropriate use in achieving vaginal delivery.
Ken Weinstein: Okay. Then very good.
Operator: Again, if you do have a question please press the number 7 on your telephone keypad. We have another question on the line from Nicholas Bakalar. Nicholas?
Nicholas Bakalar: Yeah, it’s me again. I was wondering, you know, you have certain obstetrical practices you have (inaudible), epidural, and episiotomy; that might affect the length of wait.
Nicholas Bakalar: Then on the other hand there are characteristics of these (inaudible)--
Nicholas Bakalar: --BMI babies--
Ware Branch: Larger babies.
Nicholas Bakalar: Larger babies that might also affect it.
Nicholas Bakalar: Just within the bounds of your own findings here from your study, how much is due to practice and how much is due to those changing characteristics?
Ware Branch: Oh, wow. I don’t know how Kate sees this but I don’t think we can quantify that.
Katherine Laughon: Yeah. I mean--
Ware Branch: We speculate that some is due to change in obstetric practice and certainly that speculation should drive us to look at labor process management more intensely than we have in recent times.
Katherine Laughon: I mean, I think that we just did the best that we could with the variables and information that we had. The variables that we were able to adjust for, maternal age and race and BMI, gestational age when they came in and delivered, whether or not they presented with ruptured membranes and the birth weight of the baby, when we took those into account labor was still longer. And so that’s what the third column in the tables, the adjusted median difference, that means we’ve taken all of those characteristics into account and what’s left over, that difference, it’s still pretty significant. And--
Nicholas Bakalar: Then the implication of that is that it really is practice that’s causing the difference.
Katherine Laughon: Correct. I mean, as best we could tell, sure.
Ware Branch: Yeah.
Katherine Laughon: There may be unmeasured factors that we just don’t know.
Katherine Laughon: We need future research to try to figure out what’s fully contributing to this longer labor.
Operator: We have another question on the line from Cheryl Wetzstein. Cheryl, go ahead.
Cheryl Wetzstein: Thank you so much. Yes, I noticed that your data was gathered up to the early 2000s and of course, we’ve had record high numbers of older women giving birth. It’s just a break in the barriers, in the late 30s they’re giving birth, early 40s, and also many times a multiple birth and I just wondered what your observation might be as to how will this impact the labor times and the whole climate of obstetrics at this time?
Katherine Laughon: It’s actually an important question and some collaborators in the Consortium on Safe Labor are currently investigating labor times by maternal age. So, stay tuned.
Ware Branch: I think that’s the right answer.
Cheryl Wetzstein: Okay. Thank you.
Cheryl Wetzstein: Um-hum.
Operator: We have a question on the line from Richard Knox of NPR. Richard?
Richard Knox: Hi again. Thanks. I just want to clarify something that Dr. Branch said a little while ago, about a episiotomy and training for--
Ware Branch: Operative delivering.
Richard Knox: --operative-- for episiotomy.
Ware Branch: I don’t mean to imply training for episiotomy. But I’m talking about operative delivery, yes.
Richard Knox: Well, maybe I just need to understand what you mean by training operative vaginal delivery.
Ware Branch: Uh-huh. Right. Well, I mean, one of the questions on the table based on our observation is whether a change in operative delivery may be a contributor, the rate of operative delivery may be a contributor to how long time to delivery takes. I can’t say for sure that that’s true, but I do know that the rate of operative vaginal delivery has declined quite dramatically especially in the last, I would say, decade or so. And so, we do far less of that in practice across the country today.
Richard Knox: And by operative vaginal delivery do you mean episiotomy?
Ware Branch: Forceps or vacuum. No, forceps or vacuum.
Richard Knox: Oh, I see okay. Well, that’s different.
Ware Branch: The episiotomy is a different procedure.
Richard Knox: Yes, I understand. That’s why--
Richard Knox: --I’m confused. So, when you say perhaps these findings suggest that one should take another look at the use of forceps and suctions of deliveries what are you really saying? Should we reevaluate and maybe use them more than we do now or?
Ware Branch: I’m kind of reluctant to take too much of a stance on that but I believe that in the mix of factors related to achieving successful and safe vaginal birth the role of operative delivery, which has fallen off precipitously for nonclinical reasons, should be reevaluated.
Richard Knox: Nonclinical reasons such as?
Ware Branch: Fear of fetal injury and consequences thereof.
Richard Knox: Yes. Can I ask both of you to address as simply as you can what your findings in the study in these two comparison groups suggest to you about the relationship between obstetrical practice and the longer labors and our very high cesarean rates these days?
Katherine Laughon: I think that our definitions of abnormal labor, as I said, were developed in a population of women approximately 50 years ago, they were very different contemporary obstetrical population. So, I think that we’ve shown that labor is longer and it may just be it’s natural now that labor is longer and so we may need to reevaluate intervening for a C-section, specifically for the reason of what we call labor dystocia or labor that we think is not progressing normally.
Ware Branch: Indeed.
Richard Knox: Do you want to elaborate on that Dr. Branch?
Ware Branch: Well, I think she said it well. That in the past-- I mean, the past definitions of “normal labor” have been used to draw the line in the course of the labor as to when it’s time to intervene with a cesarean, that’s a fairly sensible process management scheme, I think. But what we’ve shown is that labor is actually longer even achieving a vaginal birth today than it was 50 years ago and that certainly calls for a reassessment of when one should draw the line for cesarean delivery. And I think that’s what Kate has said as well.
Katherine Laughon: Um-hum. Right. And knowing that our cesarean delivery rate is so high, previously we found it was 30 percent in the main study from this cohort, if you think about all the women that ended up having a C-section for what was thought to be prolonged labor, labor might be even longer in the modern obstetrical cohort. We don’t know that because we weren’t able to follow those women.
Richard Knox: So, basically, your data suggests that the yardstick for when to do a cesarean may be outdated.
Katherine Laughon: Correct.
Ware Branch: Correct. That’s absolutely correct. And I think that’s an important point made by this comparison and by other features of the Consortium on Safe Labor study.
Richard Knox: Good. Thank you.
Operator: We have a question on the line now from Robin Weiss of about.com. Robin?
Robin Weiss: Hi, thank you for taking my questions. Understanding that the national cesarean rate is over 32 percent which I know is the most recent data, so it’s a little bit less when you took your data and that does include pre-labor cesarean, how does an intrapartum cesarean rate of 12 percent from your study compared to national averages?
Ware Branch: Boy, that’s-- let’s see, Kate do you know the national average right this minute?
Katherine Laughon: Yeah. I’m not sure, off the top of my head what the national average is and--
Ware Branch: Right. I don’t want to misquote that, you know.
Katherine Laughon: Yeah. The one thing I do know is that what was really surprising to us is that one out of three nulliparas, so one out of three first-time moms ended up with a C-section in this cohort. So, high.
Ware Branch: Um-hum. Right. As I sit here I don’t know the national average for nulliparous and multiparous patients in the average facility around the country.
Robin Weiss: Right.
Ware Branch: It may be worth noting that this CSL cohort was gathered from centers around the country representing the entirety of the geography but those centers were centers interested in, to some degree, by way of their participation in this study, they were interested in labor and labor management and I wouldn’t be surprised if a 12 percent overall intrapartum cesarean rate was relatively lower than the national average but I can’t be sure because I don’t have the figures in front of me.
Robin Weiss: Okay.
Katherine Laughon: Yeah. The intrapartum cesarean delivery rates are in another one of our papers, The Contemporary Cesarean Delivery Practice in the United States.
Katherine Laughon: So, it was published in the same journal in AJOG in 2010, so.
Ware Branch: There you go. Yep.
Katherine Laughon: All the numbers are in that paper.
Robin Weiss: All right. Thank you.
Operator: There are no other questions in the queue at this time. Again, if you do have a question please press the number 7 on your telephone keypad.
Operator: Another question on the line from Richard Knox of NPR. Richard?
Richard Knox: I don’t want to--
Ware Branch: You’re doing fine.
Richard Knox: Thank you so much. But I’m just-- this sounds like a dumb question but I’d just like to get Dr. Laughon to go to the next step in saying why it was really surprising to you to see a one in three cesarean rate among first-time moms?
Ware Branch: Uh-huh. Yeah.
Katherine Laughon: Well, I think we knew that the national cesarean delivery rate was rising and we thought and we were correct that the biggest contributor was due to women who had had a prior cesarean delivery electing not to undergo a trial-of-labor or what people call a VBAC. So, we knew that that was a large contributor to the rising national cesarean delivery rate but what we didn’t know is at the time, is when in labor were women having their cesarean deliveries.
And so, it was really interesting enough to find out that one out of three first-time mothers and the reason that’s important, it is because then in their subsequent pregnancies that will potentially increase the C-section rate further because if they like elect to have another repeat cesarean delivery. Really, if we wanted to decrease the national cesarean delivery rate, looking that way to decrease it in the first pregnancy is really important. That’s one of the reasons our current paper is really important because we really need to know that labor is longer in modern obstetrics so that we can avoid unnecessary deliveries if it’s just for slow labor. Does that make sense?
Richard Knox: Yes, thank you. This one mention in the paper towards the end about some of the cost implications of longer labors--
Ware Branch: Um-hum. Yeah.
Richard Knox: --and I wondered from the Intermountain data-- could you talk about that a little bit? What do you mean by that?
Ware Branch: In writing the discussion for this paper, we thought it would be interesting to at least make a general mention of the fact that longer labor is more expensive and we put that in there because we’re very much aware that health care costs are on the rise and are a national dilemma so we thought that that might cause readers of this article to focus just a little bit on their labor management process. If we’re really taking a couple of hours longer today than we did 50 years ago, and it costs us considerably more money then maybe that would drive us to improve our process or at least look into the details of why labor is longer, hoping that we might then improve our process.
Richard Knox: But I assume that the cost of a cesarean done prematurely is more than the cost of waiting a couple of more hours with (inaudible) fair.
Ware Branch: That’s fair. Yeah. Um-hum. Indeed.
Operator: We have another question on the line from Robin Weiss. Robin, go ahead.
Robin Weiss: Hi. Thanks. I’m sorry to come back but I have another question. (inaudible) as it relates to the definition of labor as far as mothers believe. Labor is longer, could it also be possible that women are coming to the hospital sooner?
Katherine Laughon: We actually looked at, you know, we don’t know the time of labor prior to when a woman presents to the hospital but one of the ways that we’ve tried to address that is looking at the cervical dilation of when they presented in labor. And in fact, if you look at the overall dilation in nulliparous they were a little bit more dilated on average than the women in the older cohort. So, we don’t think that that’s one of the reasons.
Robin Weiss: Well, because dilation is not necessarily labor. Women can be dilated well before labor begins. I’m wondering if-- and we also know that contractions aren’t necessarily labor because many women don’t understand that you can have contractions and if they aren’t getting stronger, longer, and closer together then guess what, they’re just contractions. And as annoying as they may be, it’s not labor.
I know one of the things that we’ve been seeing locally and that I’ve seen in some other smaller studies is that perhaps using different definitions of the beginning of labor for women to stay home, might be one of the ways to address that longer labor and then the additional costs of this longer labor.
Katherine Laughon: I think that you raise a good point. I think again, one of the ways that we tried to look at this is by comparing the times based on when a woman would have presented in labor and on the different cervical dilations. So, we calculated it from how long it took for them to go from 4 centimeters to complete, from 5 centimeters to fully dilated, from 6 centimeters to fully dilated, and no matter where you start labor is always longer in the longer cohort.
And really for nulliparous women, 6 centimeters is certainly pretty far along and labor is still longer by over an hour. So, I think that it’s not entirely due to what you’re suggesting.
Robin Weiss: Okay. Thank you.
Bob Bock: Okay. This is Bob Bock and I guess it looks like you’ve asked your questions, they were all good ones. If you don’t have any more then I think we will end this briefing.
Robin Weiss: Thank you guys.
Katherine Laughon: Thanks so much.
Operator: This does conclude today’s teleconference. You may now disconnect.
Robin Weiss: All right.