Trial of labor or repeat cesarean delivery in women with morbid obesity and previous cesarean delivery.

OBJECTIVE: Assess effects of body mass index (BMI) on trial of labor after previous cesarean delivery and determine whether morbidly obese women have greater maternal and perinatal morbidity with trial of labor compared with elective repeat cesarean delivery. METHODS: Secondary analysis from a prospective observational study included all term singletons undergoing trial of labor after previous cesarean delivery. Body mass index groups were as follows: normal 18.5-24.9, overweight 25.0-29.9, obese 30.0-39.9, morbidly obese 40.0 kg/m2 or greater, and were compared for failure and maternal and neonatal morbidities. The morbidly obese trial of labor and elective repeat cesarean delivery were compared for maternal and neonatal morbidities. Multivariable logistic regression analysis controlled for confounding variables. RESULTS: There were 14,142 trial of labor participants and 14,304 elective repeat cesarean delivery participants. Increasing BMI was directly associated with failed trial of labor after previous cesarean delivery: from 15.2% in normal weight (1,344) to 39.3% in morbidly obese (1,638), with combined risk of rupture/dehiscence increasing from 0.9% to 2.1% in morbidly obese women. Among morbidly obese women, trial of labor carried greater than five-fold risk of uterine rupture/dehiscence (2.1% versus 0.4%), almost a two-fold increase in composite maternal morbidity (7.2% versus 3.8%) and five-fold risk of neonatal injury (1.1% versus 0.2%) (fractures, brachial plexus injuries, and lacerations), but no neonatal encephalopathy. Morbidly obese women failing a trial of labor had six-fold greater composite maternal morbidity than those undergoing a successful trial of labor (14.2% versus 2.6%). CONCLUSION: Body mass index correlates with outcomes in trial of labor after previous cesarean delivery. Morbidly obese women undergoing a trial of labor were at increased risk for failure. Increased BMI was associated with greater composite morbidity and neonatal injury compared with elective repeat cesarean delivery, but absolute morbidities were small. Increased risks should be considered before trial of labor after previous cesarean delivery. LEVEL OF EVIDENCE: II-2.

Trial of Labor or Repeat Cesarean Delivery in Women With Morbid Obesity and Previous Judith U. Hibbard, md, Sharon Gilbert, ms, mba, Mark B. Landon, md, John C. Hauth, md, Kenneth J. Leveno, md, Catherine Y. Spong, md, Michael W. Varner, md, Steve N. Caritis, md, Margaret Harper, md, Ronald J. Wapner, md, Yoram Sorokin, md, Menachem Miodovnik, md, Marshall Carpenter, md, Alan M. Peaceman, md, Mary J. O'Sullivan, md, Baha M. Sibai, md, Oded Langer, md, John M. Thorp, md, Susan M. Ramin, md, Brian M. Mercer, md, and Steven G. Gabbe md, for the National Institute of Child Health and Human Development Maternal-Fetal Medicine Units Network* OBJECTIVE: Assess effects of body mass index (BMI) on trial of labor after previous cesarean delivery and deter­* For members of the National Institute of Child Health and Human Develop­ment Maternal-Fetal Medicine Units Network, see the Appendix. From the Department of Obstetrics and Gynecology, University of Chicago, Chicago, Illinois; George Washington University Biostatistics Center, Washington, DC; Department of Obstetrics and Gynecology, Ohio State University, Columbus, Ohio; University of Alabama at Birmingham, Birmingham, Alabama; University of Texas Southwestern Medical Center, Dallas, Texas; National Institute of Child Health and Human Development, Bethesda, Maryland; Department of Obstetrics and Gynecol­ogy, University of Utah, Salt Lake City, Utah; University of Pittsburgh, Pittsburgh, Pennsylvania; Wake Forest University, Winston-Salem, North Carolina; Thomas Jefferson University, Philadelphia, Pennsylvania; Wayne State University, Detroit, Michigan; University of Cincinnati, Cincinnati, Ohio; Columbia University, New York, New York; Brown University, Providence, Rhode Island; Northwestern University, Chicago, Illinois; University of Miami, Miami, Florida; University of Tennessee, Memphis, Tennessee; University of Texas Health Science Cen ter at San Antonio, San Antonio, Texas; University of North Carolina at Chapel Hill, Chapel Hill, North Carolina; University of Texas Health Science Center at Houston, Houston, Texas; Case Western Reserve University, Cleveland, Ohio; and Vanderbilt University, Nashville, Tennessee. Supported by grants from the National Institute of Child Health and Human Development (HD21410, HD21414, HD27860, HD27861, HD27869, HD27905, HD27915, HD27917, HD34116, HD34122, HD34136, HD34208, HD34210, HD40500, HD40485, HD40544, HD40545, HD40560, HD40512, and HD36801). In addition to the authors, the following core committee members participated in protocol development and coordination between clinical research centers: Francee Johnson, RN, and Julia McCampbell, RN; protocol/data management and statistical analysis: Elizabeth Thom, PhD; and protocol development and oversight: Atef Moawad, MD. Presented in poster format at the 25th Annual Meeting of the Society for Maternal-Fetal Medicine, Reno, Nevada, February 7-12, 2005. Corresponding author: Judith U Hibbard, MD, Professor, Maternal-Fetal Medi­cine, Department of Obstetrics and Gynecology, University of Illinois at Chicago, 820 South Wood Street, MC 808, Chicago, IL 60612; e-mail: [e-mail]. © 2006 by The American College of Obstetricians and Gynecologists. Published by Lippincott Williams & Wilkins. ISSN: 0029-7844/06 mine whether morbidly obese women have greater maternal and perinatal morbidity with trial of labor compared with elective repeat cesarean delivery. METHODS: Secondary analysis from a prospective ob­servational study included all term singletons undergoing trial of labor after previous cesarean delivery. Body mass index groups were as follows: normal 18.5-24.9, over­weight 25.0-29.9, obese 30.0-39.9, morbidly obese 40.0 kg/m2 or greater, and were compared for failure and maternal and neonatal morbidities. The morbidly obese trial of labor and elective repeat cesarean delivery were compared for maternal and neonatal morbidities. Multi­variable logistic regression analysis controlled for con­founding variables. RESULTS: There were 14,142 trial of labor participants and 14,304 elective repeat cesarean delivery participants. Increasing BMI was directly associated with failed trial of labor after previous cesarean delivery: from 15.2% in normal weight (1,344) to 39.3% in morbidly obese (1,638), with combined risk of rupture/dehiscence increasing from 0.9% to 2.1% in morbidly obese women. Among morbidly obese women, trial of labor carried greater than five-fold risk of uterine rupture/dehiscence (2.1% versus 0.4%), almost a two-fold increase in composite maternal morbidity (7.2% versus 3.8%) and five-fold risk of neo­natal injury (1.1% versus 0.2%) (fractures, brachial plexus injuries, and lacerations), but no neonatal encephalopa­thy. Morbidly obese women failing a trial of labor had six-fold greater composite maternal morbidity than those undergoing a successful trial of labor (14.2% versus 2.6%). CONCLUSION: Body mass index correlates with out­comes in trial of labor after previous cesarean delivery. Morbidly obese women undergoing a trial of labor were at increased risk for failure. Increased BMI was associated with greater composite morbidity and neonatal injury compared VOL. 108, NO. 1, JULY 2006 OBSTETRICS & GYNECOLOGY 125 Copyright© American College of Obstetricians and Gynecologists ( with elective repeat cesarean delivery, but absolute mor­bidities were small. Increased risks should be considered before trial of labor after previous cesarean delivery. (Obstet Gynecol 2006:108:125-33) LEVEL OF EVIDENCE: 11-2 A trial of labor after previous cesarean delivery has /Vgarnered much interest in the last two decades. Initially hailed as an integral factor in reducing the rising cesarean delivery rate,12 more recent concerns have focused on the safety of trial of labor for both mother and infant.3-' Questions still remain regarding appropriate candidates for trial of labor, and concerns focusing on risks and benefits for particular women or groups of women remain unanswered. Obesity is increasing in this country in both young adults and children, promising that issues surrounding mode of delivery for the obese gravida will persist into future decades.8,9 A recent statewide analysis noted that 1 in 7 cesarean deliveries is attributable to overweight and obesity.10 The mor­bidly obese gravida is an enigma in that strong arguments can be made both for and against permit­ting a trial of labor after previous cesarean delivery in these women. The impact of morbid obesity on mode of delivery, particularly in those with a previous cesarean, has only been examined in small popula­tions and with disparate results, suggesting successful trial of labor rates in the morbidly obese as low as 13% and as great as 70%, and rates of infectious morbidity reported as high as 53%.11-11 It is unclear whether those morbidly obese women failing a trial of labor are at even greater risk for morbidity than counterparts electing a repeat surgical delivery, and no report to date has addressed uterine rupture in this population. Furthermore, none of these investigations have addressed perinatal morbidity in the morbidly obese attempting trial of labor. Successful trial of labor in these gravidas may prevent serious compli­cations known to be associated with surgery in the morbidly obese. The purpose of this investigation was to 1) assess the effects of body mass index (BMI) on trial of labor after previous cesarean delivery, and 2) determine whether the morbidly obese have greater maternal and perinatal morbidity with trial of labor compared with elective repeat cesarean delivery. MATERIALS AND METHODS This was a secondary analysis of a previously re­ported prospective cohort observational study con­ducted from 1999 to 2002 at 19 participating centers.' All were part of the National Institute of Child Health and Human Development Maternal-Fetal Medicine Units Network, with participation varying from eight centers for the entire 4 years, five for the first 2 years, and six for part of the last 2 years. Data were collected on a daily basis from each center by initially screening the Labor and Delivery database or log book for all patients with a previous cesarean delivery undergoing trial of labor or repeat cesarean delivery. Information was extracted from the medical records of each mother-infant pair in a nonblinded fashion as long as the gestational age was at least 20 weeks or the infant weighed at least 500 g. Data included demographic, obstetric, intrapartum, postpartum, and neonatal in­formation. Uterine rupture was defined as a disruption or tear of the uterine muscle and visceral peritoneum or a separation of the uterine muscle with extension to the bladder or broad ligament, while uterine dehiscence was defined as a disruption of the uterine muscle with intact serosa. Definitions for other morbidities have been reported previously.' Neonatal follow-up con­tinued to 120 days after delivery or discharge from the hospital. For those infants admitted to the neonatal intensive care unit (NICU) detailed information was collected regarding the clinical course. More specific data were obtained in the situation when there was a diagnosis of maternal uterine rupture, neonatal hy­poxic ischemic encephalopathy, seizures, or cardio­pulmonary resuscitation in the first 24 hours of life, head imaging at term, 5-minute Apgar score less than 4, or umbilical cord pH less than 7.0. This study includes all term, singleton pregnan­cies with BMI, defined as kilograms per meter squared (kg/m2), of 18.5 kg/m2 or more at delivery. Lower BMIs were excluded because these were con­sidered underweight. Body mass index was subdi­vided into four categories: normal weight 18.5-24.9, overweight 25.0-29.9, obese 30.0-39.9, and mor­bidly obese 40.0 kg/m2 or greater. Maternal and neonatal outcomes in the trial of labor group were compared for trends among the four BMI categories. The morbidly obese patients undergoing trial of labor were compared with the morbidly obese elective repeat cesarean delivery group with respect to mater­nal and neonatal complications. The morbidly obese trial of labor patients were then examined in more detail to compare failed trial of labor with successful with regard to maternal and neonatal outcomes. Continuous variables were compared with the Wilcoxon rank-sum test, and categorical variables with the use of the x2 test or Fisher exact test, where appropriate. Mantel-Haenszel test for trend15 was used for dichotomous variables among BMI catego­ries, whereas for continuous variables thejonckheere- 126 Hibbard et al Morbid Obesity and Trial of Labor After Cesarean OBSTETRICS & GYNECOLOGY Copyright© American College of Obstetricians and Gynecologists ( Terpstra test1*' was used. Odds ratios (ORs) and 95% confidence intervals (CIs) were calculated for the risk of adverse outcomes in the morbidly obese group undergoing a trial of labor compared with elective repeat cesarean delivery and comparing failed with successful trial of labor. Composite morbidity was defined as one or more of the following maternal complications: endometritis, rupture, dehiscence, transfusion, surgical injury, hysterectomy, thrombo­embolic disease, and hospital stay 4 days or longer. Multivariable logistic regression analysis was used to adjust for potential confounding factors for the com­posite end point of rate of maternal adverse events and for uterine rupture in the morbidly obese trial of labor group. Nominal two-sided P values are re­ported, with statistical significance defined as a P < .05 without adjustment for multiple comparisons. Analysis was performed with SAS 8 (SAS Institute Inc, Cary, NC). Institutional review board approval was obtained at all 19 study sites for the cesarean delivery and vaginal birth after cesarean delivery (VBAC) registry. RESULTS Of the total of 378,063 births in the 4-year study period, 45,988 were singletons with a history of prior cesarean delivery. Trial of labor was undertaken by 17,898 women, and elective repeat cesarean delivery by 15,801 patients, whereas 12,289 underwent repeat cesarean delivery for either indicated cesarean deliv­ery, or they presented in labor with no documented plan for trial of labor. The current analysis focuses on trial of labor and elective repeat cesarean delivery patients, and further exclusions for these two groups included 3,357 women with preterm delivery because these fetuses were most likely smaller and trial of labor more easily accomplished or gestational age undetermined, 1,885 women for missing BMI, and 11 gravidas excluded for BMI less than 18.5 kg/m2. This resulted in a total of 14,142 trial of labor and 14,304 elective repeat cesarean delivery patients at term, 37 weeks or more of gestation, with BMI of 18.5 kg/m2 or greater available for analysis. The overall success rate for trial of labor in the study cohort was 73.0%. Demographic characteristics of all trial of labor and elective repeat cesarean delivery patients are shown in Table 1. Of the morbidly obese patients (BMI > 40.0 kg/m2) with a previous cesarean delivery, 1,638 attempted a trial of labor, and these were compared with 2,315 that had elective repeat cesarean delivery at term. Demographic characteristics for these mor­bidly obese comparison groups are also documented in Table 1. It is evident in Table 2, which compares maternal outcomes by BMI categories, that there was an in­creasing trend of failed trial of labor after previous cesarean delivery with higher maternal BMI. The failure rate in women of normal weight was 15.2%, and this increased to 39.3% in the morbidly obese. Additionally, more uterine rupture, 1.2%, and dehis­cence, 0.9%, occurred in the morbidly obese women than in the other BMI categories, but these differences were not statistically significant. However, women in the morbidly obese group were more likely to suffer rupture when compared with those in the other three BMI categories combined, P = .02. Considering a combined rupture/dehiscence rate, the risk for uter­ine disruption was significantly increased, P = .03, in the morbidly obese. Endometritis and hospital stay also significantly increased with rising BMI catego­ries. Neonatal outcomes by BMI groups are presented in Table 3 revealing that the rates of term low 5-minute Apgar scores and term admissions to the NICU rose with higher maternal BMIs. However, there was no increase in injury, sepsis, stillbirth/ abortion, or neonatal death with heavier mothers, and there was no case of hypoxic-ischemic encephalopa­thy in this cohort of neonates. To explore the outcomes in the morbidly obese women in more detail, this BMI category of patients was analyzed with respect to trial of labor versus elective repeat cesarean delivery. Table 4 documents a univariable analysis of the maternal complications sustained in both groups. An OR for rupture cannot be calculated because none occurred in the elective repeat cesarean delivery group. However, when rup­ture and dehiscence were considered together the trial of labor group had significantly higher risk (OR 5.6, 95% CI 2.7-11.7). After adjusting for maternal age, race, insurance status, birth weight, chorioamnionitis, diabetes, gestational hypertension/hemolysis, ele­vated liver enzymes, low platelets (HELLP) syn­drome, chronic hypertension, and prior vaginal de­livery in a multivariable logistic regression model, the OR for composite morbidity in the trial of labor group, excluding length of stay, was 1.8, 95% CI 1.3-2.5. Maternal adverse events in the morbidly obese were greater among those who failed trial of labor compared with those who were successful (Table 5). A multivariable analysis for uterine rupture in the mor­bidly obese group was performed controlling for the number of previous cesareans and type of labor (induced/augmented compared with spontaneous). The adjusted OR for rupture in the failed trial of labor group was 14.4, 95% CI 3.3-62.7. All outcomes VOL. 108, NO. 1, JULY 2006 Hibbard et al Morbid Obesity and Trial of Labor After Cesarean 127 Copyright© American College of Obstetricians and Gynecologists ( Table 1. Demographic Characteristics of All Morbidly Obese, Trial of Labor, and Elective Repeat Cesarean Delivery Patients Characteristic All TOL and ERCD Patients Morbidly Obese (s 40.0 kg/m') TOL (n = 14,142) ERCD (n = 14,304) TOL (n = 1,638) ERCD (n = 2,315) Body mass index (kg/m2) 32.1 ± 6.6 33.6 ± 7.0 45.2 ± 5.4 45.6 ± 5.5 Maternal age at delivery (y) 28.8 ± 5.8 30.0 ± 5.6 27.8 ± 5.4 29.3 ± 5.4 Race or ethnic group White 5,325 (37.7) 6,673 (46.7) 357 (21.8) 895 (38.7) African American 5,042 (35.7) 3,074 (21.5) 1,007 (61.5) 909 (39.2) Hispanic 3,028(21.4) 3,893 (27.2) 211 (12.9) 446(19.3) Other/unknown 747 (5.3) 664 (4.6) 63 (3.8) 65 (2.8) Payer at delivery Private 6,164 (43.6) 7,367(51.5) 516(31.5) 1,011 (43.7) Public 6,229 (44.1) 4,706 (32.9) 983(60.1) 1,049 (45.3) None/self-pay 1,747(12.4) 2,228(15.6) 138 (8.4) 254(11.0) Parity 2.0 ± 1.3 1.7 ± 1.0 2.1 ± 1.4 1.8 ± 1.0 More than one previous CD 603 (4.3) 5,363 (37.5) 94 (5.7) 947 (40.9) Prior vaginal delivery 6,919(49.2) 2,152 (15.1) 828 (50.9) 383(16.6) Last CD > 2 y 10,123(75.1) 9,173(66.1) 1,213(78.4) 1,502 (67.6) Prior indication for last CD CPD/FTP 4,519(34.2) 5,125 (38.6) 608 (39.5) 859 (39.6) Fetal tracing 3,039 (23.0) 1,670(12.6) 427 (27.7) 282 (13.0) Malpresentation 3,313 (25.1) 1,464 (11.0) 247(16.0) 174 (8.0) Other 2,350(17.8) 5,020 (37.8) 258(16.8) 854 (39.4) Diabetes 806 (5.7) 1,371 (9.6) 200(12.2) 387(16.7) Chorioamnionitis 763 (5.4) 16(0.1) 110(6.7) 2 (0.1) Chronic hypertension 194 (1.4) 258(1.8) 63 (3.8) 114 (4.9) Other maternal medical conditions* 1,556(11.0) 1,727(12.1) 268(16.4) 356(15.4) Gestati onal hyperten si on/ HFJ J J' 654 (4.6) 450(3.1) 155 (9.5) 144 (6.2) Type of labor Spontaneous 4,960 (35.7) - 401 (25.2) - Augmented 5,108 (36.8) - 565 (35.5) - Induced 3,819(27.5) - 626 (39.3) - Gestational age at delivery (wk) 39.6 ± 1.2 39.1 ±0.9 39.7 ± 1.3 39.1 ± 1.0 Birth weight (g) 3,413.0 ± 473.9 3,474.7 ± 473.7 3,493.8 ± 503.4 3,586.8 ± 524.1 TOL, trial of labor; ERCl), elective repeat cesarean delivery; Cl), cesarean delivery; CPD/FTP, cephalopelvic disproportion/failure to progress; HELLP, hemolysis, elevated liver enzymes, low platelets syndrome. Data are presented as n (%) or mean ± standard deviation. Dash represents not applicable. Every comparison in the overall population as well as in the morbidly obese is significant, with P < .001, except for type of labor where it is not applicable, and in the morbidly obese for BMI (P = .02), for chronic hypertension (P = .ll), and for other maternal medical conditions (P = .40). More than l°/o of the data were missing in the overall population and the morbidly obese, respectively, for the last cesarean delivery more than 2 years (3.8, 4.7), prior indication for last cesarean delivery (ti.8, ti.2), and for type of labor in the TOL groups only (l-8, 2.8). * Other maternal medical conditions include asthma, thyroid disease, seizure disorder, renal disease, and connective tissue disorder. cxccpt thromboembolism and hysterectomy were greater in the morbidly obese failed trial of labor group, and the composite morbidity, excluding hos­pital stay, was 6.1-fold greater. Even after adjusting for maternal age, race, insurance status, birth weight, chorioamnionitis, diabetes, gestational hypertension/ HELLP, chronic hypertension, prior vaginal delivery, and type of labor, the composite morbidity, excluding hospital stay, was greater in the failed trial of labor group (OR 6.4, 95% CI 3.9-10.4). Perinatal outcomes for infants of the morbidly obese women were examined, comparing those de­livered after trial of labor with elective repeat cesar­ean delivery (Table 6). The odds of injury to the neonate were increased five-fold, and the proportion with 5-minute Apgar scores less than 7 was also higher in those delivered after trial of labor. Again, there were no cases of hypoxic-ischemic encephalop­athy. To determine if this morbidity was more com­mon in those delivered after failed trial of labor, the morbidly obese trial of labor gravidas were further analyzed, revealing only that Apgar score of 7 or less at 5 minutes (failed 8.1% versus successful 3.1%, OR 2.7, 95% CI 1.7-4.3) and term NICU admissions 128 Hibbard et al Morbid Obesity and Trial o f Labor After Cesarean OBSTETRICS & GYNECOLOGY Copyright© American College of Obstetricians and Gynecologists f-jfc Table 2. Maternal Outcomes by Body Mass Index Categories for Trial of Labor Patients Body Mass Index Category (kg/m') Normal: Overweight: Obese: Morbidly Obese: 18.5-24.9 25.0-29.9 30.0-39.9 > 40.0 Outcome (n = 1,344) (n = 4,747) (n = 6,413) (n = 1,638) P* Failed trial of labor 204(15.2) 1,057 (22.3) 1,920(29.9) 644 (39.3) < .001 Hospital stay s 4 days 126 (9.4) 616(13.0) 1,212 (18.9) 496 (30.3) < .001 Endometritis 21 (1.6) 124 (2.6) 192 (3.0) 75 (4.6) < .001 Rupture 8 (0.6) 36 (0.8) 46 (0.7) 20(1.2) .12 Dehiscence 4 (0.3) 35 (0.7) 45 (0.7) 15(0.9) .12 Rupture/dehiscence 12 (0.9) 71 (1.5) 91 (1.4) 35 (2.1) .03 Transfusion 24(1.8) 54 (1.1) 100(1.6) 25(1.5) .59 Thromboembolism* 1 (0.07) 1 (0.02) 2 (0.03) 1 (0.06) 1.00 Wound complication* 2 (0.1) 17 (0.4) 22 (0.3) 11 (0.7) .06 Maternal surgical injury® 6 (0.4) 23 (0.5) 14 (0.2) 10(0.6) .58 Hysterectomy 4 (0.3) 6 (0.1) 14 (0.2) 5 (0.3) .57 Data are presented as n (%). * Analysis was performed with the Mantel-Haenszel test for trend across all categories, t Thromboembolism includes deep vein thrombosis or pulmonary embolism. * Wound complication includes wound infection, seroma, or hematoma. 5 Maternal injury includes broad ligament hematoma, cystotomy, bowel injury, or ureteral injury. Table 3. Neonatal Outcomes by Body Mass Index Categories for Trial of Labor Patients Outcome Body Mass Index Category (kg/m2) Normal: 18.5-24.9 (n = 1,344) Overweight: 25.0-29.9 (n = 4,747) Obese: 30.0-39.9 (n = 6,413) Morbidly Obese: > 40.0 (n = 1,638) p* Birth weight (g) 3,196.5 ± 445.5 3,370.5 ± 451.3 3,469.2 ± 471.5 3,493.8 ± 503.4 < .001 Gestational age (wk) 39.3 ± 1.2 39.5 ± 1.2 39.7 ± 1.2 39.7 ± 1.3 < .001 Apgar, 5 min s 7 26 (1.9) 120(2.5) 217(3.4) 83(5.1) <.001 Apgar, 5 min s 3 7 (0.5) 15 (0.3) 29 (0.5) 8 (0.5) .61 Injury* 10 (0.7) 49(1.0) 82 (1.3) 18(1.1) .17 Fracture 0 (0.0) 6 (0.1) 15 (0.2) 1 (0.1) .30 Brachial plexus 1 (0.1) 10 (0.2) 9(0.1) 3 (0.2) 1.00 laceration 3 (0.2) 15 (0.3) 24 (0.4) 5 (0.3) .59 Other 6 (0.4) 20 (0.4) 36 (0.6) 10 (0.6) .28 Proven sepsis 3 (0.2) 14 (0.3) 21 (0.3) 5 (0.3) .64 NICLJ admission 99 (7.4) 364 (7.7) 640 (10.0) 225(13.8) < .001 Stillbirth/abortion/neonatal death 3 (0.2) 12 (0.3) 21 (0.3) 8 (0.5) .14 N1C-U, neonatal intensive care unit. Data are presented as n (%) or mean ± standard deviation. ‘Analysis was performed with the Mantel-Haenszel test for trend for dichotomous variables and with the Jonckheere-Terpstra test for continuous variables, t Seven infants were recorded as having more than one injury. (failed 21.5% versus successful 8.8%, OR 2.8, 95% Cl 2.1-3.8) were greater in the failed trial of labor group compared with the successful, and there were no differences with regard to neonatal injuries. DISCUSSION Morbid obesity impacts women attempting a trial of labor after previous cesarean delivery in a number of very important respects. We have demonstrated that BMI was directly associated with failed trial of labor, such that in the morbidly obese nearly 40% were unsuccessful in their attempt compared with only 15% in the normal BMI women and with 27% overall. Compared with women in other BMI categories, this same group of gravidas has a significantly higher (P = .03) combined rupture/dehiscence rate, 2.1%, as well as more endometritis and longer hospital stays. Fur­ther analysis of the morbidly obese trial of labor group in fact revealed that, in comparison with those undergoing elective repeat cesarean delivery, they had a greater than five-fold increase in the combined rupture/dehiscence rate (OR 5.6, 95% Cl 2.7-11.7), VOL 108, NO. 1, JULY 2006 Hibbard et al Morbid Obesity and Trial of Labor After Cesarean 129 Copyright© American College of Obstetricians and Gynecologists f Table 4. Univariable Analysis of Maternal Complications in Morbidly Obese Patients: Trial of Labor Versus Elective Repeat Cesarean Delivery* Outcome TOL (n = 1,638) ERCD (n = 2,315) OR (95% Cl) Hospital stay s 4 days 496 (30.3) 603 (26.0) 1.2 (1.1-1.4) Endometritis 75 (4.6) 45(1.9) 2.4 (1.7-3.5) Rupture 20(1.2) 0 (0.0) - Dehiscence 15 (0.9) 9 (0.4) 2.4 (1.0-5.4) Rupture/dehiscence 35 (2.1) 9 (0.4) 5.6 (2.7-11.7) Transfusion 25(1.5) 29(1.3) 1.2 (0.7-2.1) Maternal surgical injury1- 10 (0.6) 7 (0.3) 2.0 (0.8-5.3) Hysterectomy 5 (0.3) 9 (0.4) 0.8 (0.3-2.4) Wound complication* 11 (0.7) 44 (1.9) 0.3 (0.2-0.7) Thromboembolic disease8 1 (0.06) 1 (0.04) 1.4 (0.1-22.7) Composite morbidity 524 (32.0) 635 (27.5) 1.2 (1.1-1.4) Composite morbidity, excluding stay 117(7.2) 88 (3.8) 1.9(1.5-2.6) TOL, trial of labor; ERCD, elective repeat cesarean delivery; OR, odds ratio; CI, confidence interval. Data are presented as n (°/o). Dash represents not applicable. * Morbidly obese: body mass index > 40.0 kg/m2. t Maternal surgical injury includes broad ligament hematoma, cystotomy, bowel injury, or ureteral injury. ? Wound complication includes wound infection, seroma, or hematoma, not. included in composites. § Thromboembolic disease includes deep vein thrombosis or pulmonary embolism. Table 5. Maternal Outcomes of the Morbidly Obese Body Mass Index Group* Outcome Failed TOL (n = 644) Successful VBAC (n = 994) OR (95% Cl) Hospital stay s 4 days 435 (67.5) 61 (6.1) 31.8 (23.4-43.3) Endometritis 56 (8.7) 19(1.9) 4.9 (2.9-8.3) Rupture 18(2.8) 2 (0.2) 14.3 (3.3-61.7) Dehiscence 12 (1.9) 3 (0.3) 6.3(1.8-22.3) Rupture/dehiscence 30 (4.7) 5 (0.5) 9.7 (3.7-25.0) Transfusion 21 (3.3) 4 (0.4) 8.3 (2.9-24.4) Maternal surgical injury* 9(1.4) 1 (0.1) 14.1 (1.8-111.4) Hysterectomy 4 (0.6) 1 (0.1) 6.2 (0.7-55.7) Wound complication* 11 (1.7) 0 (0.0) - Thromboembolism8 1 (0.2) 0 (0.0) - Composite morbidity 450 (69.9) 74 (7.5) 28.8 (21.5-38.5) Composite morbidity, excluding stay 91 (14.2) 26 (2.6) 6.1 (3.9-9.6) TOL, trial of labor; VBAC, vaginal birth after cesarean; OR, odds ratio; CI, confidence interval. Data are presented as n (%). Dash represents not. applicable. * Morbidly obese: body mass index > 40.0 kg/m2. t Maternal surgical injury includes broad ligament, hematoma, cystotomy, bowel injury, or ureteral injury. * Wound complication includes wound infection, seroma, or hematoma, not. included in composites. § Thromboembolism includes deep vein thrombosis or pulmonary embolism. and although no differences were noted in thrombo­embolic events, wound complication, hysterectomy, transfusion rates, or maternal injuries when evaluated separately, there was a nearly two-fold increase in composite maternal morbidity. Within the morbidly obese trial of labor group, those failing the attempted vaginal delivery suffered six-fold greater morbidity over their successful counterparts. This risk was actu­ally similar to the 6.8 times increased risk of one or more maternal adverse events in the overall popula­tion failing trial of labor compared with those who were successful.7 Additionally, the neonates of the morbidly obese were noted to have a five-fold greater risk for injury after delivery with trial of labor com­pared with the elective repeat cesarean delivery group, although there was no difference in injured neonates between those succeeding and those failing the trial of labor. Landon et al7, in a large prospective cohort from which the current investigation was derived, recently documented that trial of labor after previous cesarean delivery in the term general obstetric population is indeed associated with a 1.6-fold increase in maternal morbidity (5.5% trial of labor versus 3.6% elective 130 Hibbard et al Morbid Obesity and Trial of Labor After Cesarean OBSTETRICS & GYNECOLOGY Copyright© American College of Obstetricians and Gynecologists ( Table 6. Univariable Analysis of Neonatal Complications in Morbidly Obese Patients: Trial of Labor Versus Elective Repeat Cesarean Delivery* Outcome TOL (n = 1,638) ERCD (n = 2,315) OR (95% Cl) Apgar, 5 min < 7 83(5.1) 39(1.7) 3.1 (2.1-4.6) Apgar, 5 min s 3 8 (0.5) 5 (0.2) 2.3 (0.7-6.9) Injury'1' 18 (1.1) 5 (0.2) 5.1 (1.9-13.8) Fracture 1 (0.1) 0 (0.0) - Brachial Plexus 3 (0.2) 0 (0.0) - Laceration 5 (0.3) 4 (0.2) 1.8 (0.5-6.6) Other 10 (0.6) 1 (0.04) 14.2 (1.8-111.0) Proven sepsis 5 (0.3) 6 (0.3) 1.2 (0.4-3.9) NICLJ admission 225 (13.8) 292 (12.6) 1.1 (0.9-1.3) Stillbirth /abortion/neonatal death 8 (0.5) 5 (0.2) 2.3 (0.7-6.9) TOL, trial of labor; ERCD, elective repeat cesarean delivery; OR, odds ratio; CI, confidence interval; NICU, neonatal intensive care unit. Data presented as N (°/o). Dash represents not applicable. * Morbidly obese: body mass index > 40.0 kg/m2. t One infant was recorded as having both brachial plexus injury and fractured humerus. repeat cesarean delivery) and a 2.9 times increased risk (0.38% trial of labor versus 0.13% elective repeat cesarean delivery) of stillbirth, neonatal death, or hypoxic-ischemic encephalopathy, 0.46 cases of the latter per 1,000 women undergoing trial of labor. It is not surprising, in view of the rising cesarean rate, as well as obesity rate, that the obstetrician is faced with an increasing number of morbidly obese gravidas seeking counsel on the issue of choosing a trial of labor versus an elective repeat cesarean delivery. Because surgical deliveries in such patients are tech­nically difficult, prolonged, and carry higher risks of infection, thromboembolic events, and longer hospi­tal stays, most obstetricians usually wish to avoid this type of delivery if possible. Previous studies available to guide the obstetri­cian in specifically counseling morbidly obese pa­tients regarding trial of labor versus elective repeat cesarean delivery is sparse, derived from small num­bers, and reaches varying conclusions. Chauhan et al11 noted an 87% failure rate in a group of 30 morbidly obese women who attempted a trial of labor, with a 53% infectious morbidity rate, but there was no comparison with a control group of normal- weight women undergoing trial of labor. They were, however, compared with 39 similarly obese women undergoing elective repeat cesarean delivery. The large disparity from our much lower 40% failure rate in the morbidly obese might be explained by the mean BMI of 57 kg/m2 in their failed trial of labor patients, higher than the mean BMI in our morbidly obese trial of labor group, and possibly contributing to their lower success rate. Regarding trial of labor failure rates, our results were similar to those of Edwards et al12 who, in a retrospective cohort of 61 patients, noted a 43% failure rate with an average BMI of 46.5 kg/m2. They also noted a lower rate of infectious morbidity than the aforementioned investigation, 24.6% over­all, but still much greater than our 4.6%. A further analysis13 of the same morbidly obese trial of labor patients previously described by Chauhan et al11 was undertaken, comparing the morbidly obese cohort with lean women with regard to success rates, and noted that trial of labor success was significantly reduced in the morbidly obese. How­ever, 90% of the lean trial of labor control group had a previous vaginal birth in contrast to only 13% in the morbidly obese cohort, greatly confounding the comparison. Similar to the current work, Durn- wald et al17 retrospectively noted a decrease in the rate of successful trial of labor with increasing BMI (54.6% success rate in those with BMI S 30 kg/m2), but there was no separate analysis of those with BMI of 40 kg/m2 or greater, and there was no analysis of morbidity. Controlling for confounding factors in a retrospective investigation, Goodall et al11 recently documented a two-fold increase in failed trial of labor in 66 morbidly obese gravidas (s 40 kg/m2) compared with normal-weight coun­terparts, but their failure rate was only 30%. Neither of the two previously mentioned investigations compared the obese cohorts with their counterparts undergoing elective repeat cesarean delivery. The strength of the current work lies in the fact that it was based upon recent data prospectively gathered from 19 tertiary medical centers through­out this country. It involves a large cohort of patients, allowing for comparison of more than 1,600 morbidly obese gravidas undergoing trial of VOL. 108, NO. 1, JULY 2006 Hibbard et al Morbid Obesity and Trial o f Labor After Cesarean 131 Copyright© American College of Obstetricians and Gynecologists f-jfc labor with over 2,300 having elective repeat cesar­ean delivery, while also allowing a detailed analysis of the morbidly obese trial of labor cohort com­pared with lower BMI categories. Despite the pro­spective nature of the current work, it was impos­sible to know how individual women were counseled by their obstetricians regarding trial of labor versus elective repeat cesarean delivery. It was possible that individual practitioners counseled in favor of one mode of delivery, thus influencing their patients' choice and introducing bias. Further­more, in the trial of labor group, management of the patients' labor and details and timeliness of operative interventions are unknown. Finally, even though this was the largest cohort of morbidly obese women undergoing trial of labor of which we are aware, the numbers are not sufficient to address rare outcomes such as maternal or neonatal mor­tality or neonatal hypoxic ischemic encephalopa­thy. In summary, morbid obesity in trial of labor con­ferred not only a higher uterine rupture/dehiscence rate (2.1%) compared with their less heavy counterparts, but also rupture/dehiscence was increased five-fold over those electing repeat cesarean (0.4%). Furthermore, the six-fold greater maternal morbidity (14.2%) noted in the morbidly obese failing their trial of labor is of concern. It is disquieting that the neonates of the morbidly obese undergoing trial of labor had a greater chance of sus­taining injury (1.1% versus 0.2%) with this mode of delivery. Despite these concerns, the absolute risks of morbidity (7.2%) for the morbidly obese gravidas un­dergoing trial of labor remain small. Moreover, 60% of the morbidly obese were successful in their trial of labor, although our ability to know which patients will ulti­mately be in this favorable category is just beginning to emerge. Factors such as need for induction of labor, prior indication for cesarean delivery, in particular, cephalopelvic disproportion and failure to progress, or lack of previous vaginal delivery have been demon­strated to be associated with lower success rates in our overall population of women undergoing trial of labor18. We believe all these factors must be taken into consid­eration in counseling the morbidly obese regarding their choices for mode of delivery with previous cesarean birth. REFERENCES 1. NIH Consensus Development Task Force statement on cesar­ean childbirth. Am J Obstet Gynecol 1981;139:902-9. 2. Public Health Service. Healthy People 2000: National health promotion and disease prevention objectives: full report with commentary. 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Ramos-Brinson, M. Moran, D. Scott The George Washington University Biostatistics Center, Washington, DC: E. Thom, H. Juliussen-Steven- son, M. Fischer 132 Hibbard et al Morbid Obesity and Trial of Labor After Cesarean OBSTETRICS & GYNECOLOGY Copyright© American College of Obstetricians and Gynecologists ( Ohio State University, Columbus, OH: J. lams, F. Johnson, S. Meadows, H. Walker University of Alabama at Birmingham, Birmingham, AL: D. Rouse, A. Northen, S. Tate University of Texas Southwestern Medical Center, Dal­las, TX: S. Bloom, J. McCampbell, D. Bradford National Institute of Child Health and Human Develop­ment: D. McNellis, K Howell, S. Pagliaro University of Utah, Salt Lake City, UT: M. Belfort, F. Porter, B. Oshiro, K. Anderson, A. Guzman University of Pittsburgh, Pittsburgh, PA: K. Lain, M. Cotroneo, D. Fischer, M. Luce Wake Forest University, Winston-Salem, NC: P. Meis, M. Swain, C. Moorefield, K. Lanier, L. Steele Thomas Jefferson University, Philadelphia, PA: A. Sciscione, M. DiVito, M. Talucci, M. Pollock Wayne State University, Detroit, MI: M. Dombrowski, G. Norman, A. Millinder, C. Sudz, B. Stefly University of Cincinnati, Cincinnati, OH: T. Siddiqi, H. How, N. Elder Columbia University, New York, NY: F. Malone, M. D'Alton, V. Pemberton, V. Carmona, H. Husami Brown University, Providence, RI: H. Silver, J. Till- inghast, D. Catlow, D. Allard Northwestern University, Chicago, IL: M. Socol, D. Gradishar, G. Mallett University of Miami, Miami, FL:G. Burkett, J. Gilles, J. Potter, F. Doyle, S. Chandler University of Tennessee, Memphis, TN: W. Mabie, R. Ramsey University of Texas Health Science Center at San Antonio, San Antonio, TX: O. Langer, S. Barker, M. Rodriguez University of North Carolina at Chapel Hill, NC: K. Moise, K. Dorman, S. Brody, J. Mitchell University of Texas Health Science Center at Houston, Houston, TX: L. Gilstrap, M. Day, M. Kerr, E. Gildersleeve Case Western Reserve University, Cleveland, OH: P. Catalano, C. Milluzzi, B. 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