MCHB/EPI Miami Conference — December 7 - 9, 2005

Preterm Delivery: Current Challenges — Transcript

NANCY GREEN: Thank Bao-Ping and thank you to the organizers for inviting me to come to speak to this remarkable group and this remarkable setting which always strikes me as an incredible juncture of nature and manufacture and certainly we're very grateful for the topic of preterm birth as it relates to the prematurity campaign that the March of Dimes has focused on and there are a number of March of Dimes staff members in the audience. I'm going to acknowledge my collaborators at the end but just to mention much of the data that I'm going to show you is from the March of Dimes parinatal data center led by Dr. Joann Patrini who's in the back there. Okay.

So consistent with I think Claudia's elegant presentation I'm going to focus on a layer of not of placenta but a layer of the epidemiology of preterm birth mainly the late preterm and I think this group already knows that in terms of numbers this is where the power is. So really we're beginning to dig into who are these babies and what's going on. Okay.

So as you've heard from Bao-Ping and your readings preterm birth is increasing annually actually the most recent data from 2004 suggests that the rates are even higher, 12.5 percent up from 12.3 percent the year before and that represents a 30 percent increase over the last couple of decades and there are enumerable factors, some biologic, some practice, some epidemiologic and social associated with the increase in preterm birth and amongst those factors are the medical practices that was eluded to and I'll show you a little bit of data on that. The increase in cesarean sections now up to 29 percent of all births and also multiples with again as you've heard a very constant rate of very preterm birth and I'm going to show you a number of, well, several studies mostly new in the literature on looking at clinical outcomes comparing the late preterm, 34 to 36 weeks with the full term but I'd like to say that the literature on those clinical outcomes is young and small, so it's actually easy to show you most of the data and clearly more needs to be done to look at this population and also to understand how they do in the longer run. We don't have any post discharge or post neonatal period data yet. Okay.

So this group knows what I'm talking about. As I mentioned the late preterm, I'm going to use the term late preterm but it's also--the other term is near term. Some people view it as 34 to 36 weeks, some as 35 to 36 weeks and there was a recent (inaudible) there was a meeting held by NICHD looking at this group and there, too, we argued about terminology and gestational definitions and so that work is ongoing and will be published in a special supplement in the seminars of parinatology in 2006. Okay. So if you just look at the slices of the pie amongst a singleton preterm births and most of the epi data I'm going to show you focuses on the singletons. What's really quite striking is that 40 percent of all preterm births are at 36 weeks, so actually if you think about that our national campaign to collaborating with most if not all of you and certainly CDC and HRSA and the other government agencies present here if you think about our goal to decrease preterm birth in a very simplistic way, if you have the number of births at 36 weeks, you know, you get to the goal of decreasing preterm birth to about ten percent of the population. So and certainly if you look at the near term or the late preterm, 34 to 36 weeks, that's 74 percent of all singleton preterm births so it's quite striking.

So I'm going to talk a little bit about who are these infants and it's a heterogeneous group and so the clinical data I'm going to show you in a minute I think largely reflects the heterogeneity of this group and actually Bao-Ping showed that nice (inaudible) diagrams of the overlap between preterm birth and low birth weight IUGR and there's also another group in this mix of kids with birth defects and other complications. So it's a very heterogeneous group but the reason that actually we favor using the segment of 34 to 36 weeks has to do with the obstetric management and that is a cut off for use of maternal antenatal steroids, not past 34 weeks. That used to decrease the incidence of respiratory distress and shouldn't be lost that that cut off of 34 weeks in terms of antenatal steroids also impacts obstetric practice in that it's often a time point beyond which to politics are not liberally given or at least are in some centers withheld. So I think from a management perspective it's very important, also from a pediatric management perspective many of these kids bounced to the so called normal nursery and for those of us who in our training spent time in this normal nursery which is, sort of, a nightmare of management and these kids often don't do that well and bounce up to the NICU or require a lot of anxiety from the perspective of the providers and I think that there are implications for nursing in these nurseries as well.

Okay. So I'm going to show you some data again from the parinatal data center at March of Dimes on cutting into who these babies are in this 34 to 36 week group and you can see here that by racial ethnic group what you've heard before in different shapes of curves that there's a disproportionate percentage of preterm births in the African/American population but what I'll show you hopefully on the next side is that--and this is a complicated slide, so I'm going to spend a moment going through it that the rate of increase is largely in the white and Hispanic populations. So this stacked coin bar graph divides singleton preterm birth by race and ethnicity comparing '92 and 2002 data so on the left Hispanic and then going to the right non-Hispanic white, non-Hispanic black and the total. So if you look at the right hand side of the image for a moment looking at the dark blue which is 34 to 36 weeks you can see that that is the group that has increased over the last decade from 6.9 percent in '92 now to 7.7 percent in 2002 with the other--not only the less than 32 weeks flat but also the 32 and 33 week flat and if you then move your eyes over towards the left which is the non-Hispanic white you can see that that's actually the area of the largest increase from 5.7 percent the 34 to 36 weeks in '92 to 7 percent in '02 and so that's growing.

The Hispanic group is paralleling the non-Hispanic white trend and what's interesting is that I think the non-Hispanic black in that same gestational length group has gone down from 10.9 percent to 10.5 percent. So clearly when we think about this rise in preterm birth this gives us some clues as to where we need to put our efforts and this just goes a little bit finer and again very complicated but if you just look at the very top, the dark blue, which is the 36 weeks then the royal blue being 35 weeks, if you have very good vision you can see that the non-Hispanic white in this--that that's, you know, (inaudible) this is where the money is in terms of rising preterm births that the 36 weeks gestation has gone from 3.1 percent to 3.9 percent of the non-Hispanic white with (inaudible) but somewhat less dramatic increase in the 35 weeks and again similarly in the Hispanics '92 to 2002 that the 36 week, again, looking only at the top of the stack has gone from 3.7 percent to 4.1 percent, so pretty dramatic increases.

Okay. Now, this is a complicated slide, so bear with me. This actually was the creation of my (inaudible) in the parinatal data center. So this looks at the trends in caesarian sections and inductions, so this so-called medically indicated group of deliveries based on birth certificate data and the vertical bars denote the 34 to 36 week gestations but overall you can see that the trends from '92, yeah, '92 and 2002 are that inductions are indeed going up as Bao-Ping mentioned earlier and that caesarian sections are increasing but particularly for the lower gestational ages. So certainly medical intervention is increasing and then if you look specifically at the 34 to 36 weeks you can see quite dramatic increases in the inductions but also substantial increases in the caesarian sections for this group. So again, corroborating what you already know and what you've heard in terms of the importance of obstetric management in the demographics.

Okay. Now, I'm going to show you some infant mortality data and then I'm going to shift to morbidity data. As you know at 34, 36 weeks the mortalities are low but and this is dated '95 in the green and 2002 in the red and comparing on the left 34 to 36 weeks with 37 to 41 weeks and I think this is actually dramatic that that for say '02 that the infant mortality rates are 7.7 per thousand for the 34 to 36 week and 2.5 to the 37 to 41 weeks. Now, that is not to say that there is that much difference in mortality between these two groups. That's ridiculous in terms of management, what happens to them in the nursery. I think these data are telling us that the groups are different, that many more of the 34 to 36 week infants probably have birth defects, infections and we really actually need to dig into to this to see what the causes of death are to better understand it but I use this data to indicate that they are somewhat different although clearly somewhat overlapping entities not that delivery a few weeks early directly has a major impact on mortality. I'm going to skip the next slide.

This is just neonatal mortality which corroborate what I've said about infant mortality. Okay. So what are the morbidities? And as I'm suggesting we really do need to separate the causes of late preterm birth and the effects, certainly in terms of our immediate morbidities, though, these clearly are related to birth a little bit too early and those morbidities are respiratory distress, jaundice, feeding difficulties, hypoglycemia, temperature instability, sepsis and while all of these have, again, low associated mortalities the impact on cost and I'll show you a little bit of data and you saw some of that from Bao-Ping earlier is substantial. They are associated with increase in neonatal ICU use and readmission and increased cost and (inaudible) no data on long term outcomes and we'd very much like to help stimulate some of that analysis.

Okay. So this is data from Marvin Wang from Mass General. It's a small study but looking at length of hospital stay and from full term in the gray which you can probably barely see and then the black so it's skewed so your attention is where I want you to look at the 35 to 37 week group and you can see that the average length of stay is clearly higher with plenty of outliers for this near term group. Okay. And in another study looking at the frequency of respiratory distress sepsis and apnea 34, 35 and 36 weeks and 34 is polka dots, 35 is a solid bar and 36 is striped, looking at RDS, sepsis and apnea separately you can very clearly see that there are dramatic differences even between gestational weeks. Again, I'm not suggesting that it's because they're a week early but they're often associated with other factors but I think that this very nicely documents that there are significant morbidities and that it does vary if you look finally at by week of gestation and then looking at clinical outcomes this is full term versus near term. This is again from Marvin Wang's data looking at a number of clinical complications, temperature instability, hypoglycemia, needing an IV, respiratory distress and clinical jaundice, the red arrows indicate where the near term infants are that began. These infants have higher rates of complications compared to their full term counterparts.

Okay. And this you can't read so don't panic but looking at excess hospital costs and I would just refer you to this very good paper by Gilbert et al and OBGYN in 2003 looking at excess in hospital cost by gestational week and confirming what you would know or intuit that is that per birth that these, you know, 34, 35, 36 weeks babies don't have that much higher cost although some up to six to ten fold higher but, you know, certainly the numbers as I showed you before are so great that it really helps drive the excess health costs for these infants.

Okay. So this is a study that I have to confess I manipulated from Gabriel Escobar from the Kaiser Data. Gabriel's not here, right? Okay. So looking at rehospitalization rates, so again I refer you to his paper to get the real data but I didn't change the numbers, just compacted. So looking at NICU admission, basically what this says is for kids who are 34 to 36 weeks or even less than 34 weeks if they have spent a day or more in the NICU compared to those who never passed through the doors of the NICU, who went right to the well-child nursery that the rates of readmission are very much different. So those infants who never went to a NICU had a three-fold higher odds ratio of readmission than those who didn't. So while I'm saying that there are differences in these babies I'm also suggesting that we need to look at these, even the non-complicated 34 to 36 week babies because we may be under treating them at the time of--in the immediate post-partum period. It's just a question I'm raising and then if you look at (inaudible) there's two studies here. Not to go into detail but most of you know that (inaudible) which peaks at four to seven days post delivery there are higher rates in these 34 to 36 weeks infants and I'm just going to mention that American Academy of Pediatrics last year came out with new guidelines for assessing neonatal jaundice which does not include universal laboratory assessment or (inaudible) assessment of levels of jaundice and that those guidelines go down to 35 weeks. So I guess what I'm suggesting is that here in this particular complication of the late preterm that jaundice is something we need to pay more attention to.

Okay. Now, this actually an excellent paper by Gladstone et al in An American Journal of (inaudible) looking at the near term infant at one tertiary medical center and then that 34 week babies represented 1.6 percent of deliveries, 9 percent of NICU admissions and 19 percent of NICU bed days. So again corroborating that these are often complicated kids that we really do need to pay attention to because of the numbers and in fact I'm not going to say this but that others have said that moderately preterm infants this looking at the 36 weeks are underprivileged newborns, you know, like I said I didn't say that.

Okay. So there are significant clinical issues for these babies and these ideas were generously donated by Mark (inaudible) from NICHD and these are the issues and again you heard a little bit about this earlier from the other speakers that prolonging a high risk pregnancy from 32 to 36 weeks versus shortening a less high risk pregnancy from term. So I think that's an issue that the morbidity or mortality may or may not have been due to the shorter gestation but in some cases may be and that these as I mentioned that these infants probably do need more attention in the nursery and there are certainly medical and socio economic risks associated with these kids as well given, you know, what Claudia Holzman told you about poverty and the association with good clinical follow up.

So I think there are a lot of issues here to think about and March of Dimes, as I said, is, sort of, digging into this and if anybody would like to discuss some data set analysis we'd be happy to discuss it with you and we're collaborating with a number of groups including the (inaudible) which I can never--Women's and Obstetric Nurses Organization that actually has an initiative called the near term initiative looking at management issues in nurseries for these infants. So I applauded their activities and I just wanted to acknowledged Michael (inaudible), Joann Patrini, Vonnie who's here, Carla Damus (inaudible) who is over here, Becky Russell and Mark (inaudible) from NICHD and thank you for your attention.