Obstetrics & Gynecology:
Comparison of Maternal and Infant Outcomes From Primary Cesarean Delivery During the Second Compared With First Stage of Labor
Alexander, James M. MD1; Leveno, Kenneth J. MD1; Rouse, Dwight J. MD2; Landon, Mark B. MD3; Gilbert, Sharon MS, MBA15; Spong, Catherine Y. MD16; Varner, Michael W. MD4; Moawad, Atef H. MD5; Caritis, Steve N. MD6; Harper, Margaret MD7; Wapner, Ronald J. MD8; Sorokin, Yoram MD9; Miodovnik, Menachem MD10; O'Sullivan, Mary J. MD11; Sibai, Baha M. MD12; Langer, Oded MD13; Gabbe, Steven G. MD14; for the National Institute of Child Health and Human Development (NICHD) Maternal–Fetal Medicine Units Network (MFMU)
From the Departments of Obstetrics and Gynecology at the 1University of Texas Southwestern Medical Center, Dallas, Texas; 2University of Alabama at Birmingham, Birmingham, Alabama; 3Ohio State University, Columbus, Ohio; 4University of Utah, Salt Lake City, Utah; 5University of Chicago, Chicago, Illinois; 6University of Pittsburgh, Pittsburgh, Pennsylvania; 7Wake Forest University, Winston-Salem, North Carolina; 8Thomas Jefferson University, Philadelphia, Pennsylvania; 9Wayne State University, Detroit, Michigan; 10University of Cincinnati, Cincinnati, Ohio; 11University of Miami, Miami, Florida; 12University of Tennessee, Memphis, Tennessee; 13University of Texas Health Science Center at San Antonio, San Antonio, Texas; 14Vanderbilt University, Nashville, Tennessee the 15George Washington University Biostatistics Center, Washington, DC; and the 16National Institute of Child Health and Human Development, Bethesda, Maryland.
*For members of the NICHD MFMU, see the Appendix.
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, and HD36801).
The authors thank Elizabeth Thom, PhD, for protocol, data management, and statistical analysis, and Francee Johnson, BSN, and Julia Gold, BSN/APN, for protocol development and coordination between clinical research centers.
Corresponding author: James M. Alexander, MD, Department of Obstetrics and Gynecology, University of Texas Southwestern Medical Center at Dallas, 5323 Harry Hines Boulevard, Dallas, TX 75235-9032; e-mail: email@example.com.
OBJECTIVE: To compare maternal and neonatal outcomes when primary cesarean delivery is performed in the second stage of labor compared with the first stage.
METHODS: Between January 1, 1999, and December 31, 2000, a prospective observational study of primary cesarean deliveries was conducted at 13 university centers comprising the National Institute of Child Health and Human Development Maternal–Fetal Medicine Units Network. The primary outcomes of interest included a maternal composite (composed of at least one of the following: endometritis, intraoperative surgical complication, blood transfusion, or wound complication) and neonatal composite (which included at least one of the following: Apgar score of 3 or less at 5 minutes, neonatal death, neonatal intensive care unit admission, seizure, delivery room intubation in the absence of meconium, or fetal injury).
RESULTS: A total of 11,981 cesarean deliveries were available for analysis: 9,265 were performed in the first stage and 2,716 in the second stage. Cesarean deliveries performed in the second stage were associated with longer operative times, epidural analgesia, chorioamnionitis, and higher birth weight (all P<.001). The maternal composite index was slightly increased in women undergoing cesarean delivery in the second stage of labor, primarily due to uterine atony, uterine incision extension, and incidental cystotomy. This difference was significant after multivariable analysis (odds ratio 1.21, 95% confidence interval 1.07–1.37). After multivariable analysis, the neonatal composite did not differ significantly between groups (odds ratio 0.96, 95% confidence interval 0.84–1.08).
CONCLUSION: Cesarean delivery in the second stage of labor is associated with slightly increased maternal but not neonatal composite morbidity.
LEVEL OF EVIDENCE: II
Cesarean delivery in the second stage of labor accounts for approximately one fourth of all primary cesareans.1 Although the morbidity of cesarean in the second stage of labor has been reported in comparison with operative vaginal delivery, the morbidity in comparison with cesarean delivery in the first stage of labor is less well known.2–4 Maternal and infant outcomes may be affected by the timing of cesarean delivery. For example, second stage cesareans are more difficult technically due to engagement of the fetal head predisposing the mother to surgical injuries such as cystotomy. Also, the delay of cesarean delivery until the second stage of labor may put the fetus at risk for morbidity due to hypoxia. In an effort to examine these and other contemporary issues related to cesarean delivery, the National Institute of Child Health and Human Development (NICHD) Maternal Fetal–Medicine Units Network (MFMU) performed an observational study of primary cesarean births between January 1, 1999, and December 31, 2000. Using data from this registry, we compared maternal and infant outcomes when cesarean deliveries were performed in the second compared with the first stage of labor.
MATERIALS AND METHODS
The MFMU was established in 1986 by the NICHD to study clinical issues in obstetrics. The cesarean registry was an observational study designed to assess several contemporary issues related to cesarean delivery. Between January 1, 1999, and December 31, 2000, all women undergoing a primary cesarean delivery with an infant of at least 500 g or 20 weeks gestation at a participating center were prospectively ascertained. Each of 13 centers participating in this NICHD MFMU Network study obtained institutional review board approval before enrollment.
The primary outcomes for this study have been previously reported.5 In brief, detailed information regarding medical and obstetric history, intrapartum course, postpartum complications, and infant outcome were abstracted directly from maternal and infant charts by specially trained and certified research nurses. All data were entered into a computer, without unique participant identifiers, and transmitted electronically to the George Washington University Biostatistics Center on a weekly basis. Electronic edit reports were generated each week and transmitted back to each center for correction or clarification. For this analysis, maternal and neonatal outcomes were compared between those women who underwent primary cesarean delivery in the second stage of labor and those who underwent primary cesarean delivery in the first stage. Demographic information and labor characteristics were compared. Chorioamnionitis was defined as a temperature 38°C or more and no other infection; operative time was the time from skin incision to skin closure. The primary outcomes of interest for this secondary analysis were a maternal composite outcome and a neonatal composite outcome. The maternal composite outcome included one or more of the following: endometritis (defined as a persistent postpartum temperature 38°C or more with uterine tenderness and no other infection), intraoperative surgical complications, blood transfusion, or wound complication (includes infection at skin incision site, seroma or hematoma). Intraoperative complications included uterine atony, uterine or hypogastric artery ligation, intraoperative transfusion, broad ligament hematoma, cystotomy, a T or J uterine incision extension, or ureteral or bowel injury. The neonatal composite included at least one of the following: Apgar of 3 or less at 5 minutes, neonatal death, neonatal intensive care unit admission for at least 24 hours, seizure, delivery room intubation in the absence of meconium, or fetal injury. The individual components of the composites were also examined.
Statistical analysis included the Wilcoxon rank sum test for continuous variables and the χ2 or Fisher exact test for categorical variables. Unless otherwise noted, the response rate to the variables was 95% or greater. Multivariable logistic-regression analyses were performed for two composite outcomes, adjusting for demographic and labor differences in the two groups, as well as for center of enrollment dichotomized by type of medical insurance at delivery. Nominal two-tailed P values are reported with statistical significance considered as a P value of <.05. No adjustment was made for multiple comparisons. SAS 8 software (SAS Institute, Cary, NC) was used for analysis.
During the 2-year study period, there were a total of 184,387 deliveries in the MFMU Network. 23,491 women underwent primary cesarean delivery and 13,269 of these were in women with a singleton, vertex gestation of at least 37 weeks who delivered a liveborn, nonanomalous fetus. A total of 1,288 participants were excluded due to incomplete information about cervical dilation, leaving 11,981 primary cesarean deliveries for analysis meeting the inclusion criteria. Of these, 9,265 were performed in the first stage of labor and 2,716 in the second stage. Selected maternal demographic characteristics are shown in Table 1. Women undergoing cesarean delivery in the second stage were more likely to be older, nulliparous, white, and had a smaller body mass index at delivery.
Selected intrapartum characteristics are shown in Table 2. As anticipated, labor was more than 1 hour longer in women who underwent cesarean in the second stage. Dystocia was the most common indication for cesarean in both groups; however, cesarean for fetal distress and other indications were more commonly seen in women who had cesareans in the first stage of labor. Cesarean deliveries performed in the second stage were significantly longer, both overall and from the time of the initial skin incision to delivery of the infant (P<.001). However, the absolute increases in surgical times were small.
Selected maternal outcomes are shown in Table 3. Intraoperative complications were significantly increased in women undergoing cesarean delivery in the second stage due to a higher incidence of uterine atony, a T or J uterine incision extension, and incidental cystotomy. Shown in Table 4 are neonatal outcomes according to the stage of labor at cesarean delivery. The women who underwent cesarean delivery in the second stage had slightly larger infants, the mean increase in birthweight being 126 g. Fetal injury was more common in women who underwent cesarean delivery in the second stage of labor. Neonatal intensive care unit admission of 24 hours or more was more common in women who underwent first-stage cesarean delivery.
The maternal composite outcome was identified in 1,819 (19.6%) of women undergoing cesarean in the first stage of labor as compared with 589 (21.7%) in the second stage (odds ratio 1.13, 95% confidence interval 1.02–1.26), and the neonatal composite outcome was identified in 2,117 (22.9%) of women undergoing cesarean in the first stage of labor as compared with 538 (19.8%) in the second stage (odds ratio 0.83, 95% confidence interval 0.75–0.93). Table 5 shows the unadjusted and adjusted odds ratios for the maternal and neonatal composite outcomes. The maternal composite index was slightly increased in women undergoing cesarean delivery in the second stage of labor. Adjustment was made for maternal age at delivery, parity, body mass index at delivery, operative time, labor onset to delivery time, oxytocin use, indication for cesarean, chorioamnionitis, and center dichotomized by health insurance coverage at delivery. The adjusted maternal composite outcome remained significantly increased with cesarean delivery in the second stage, whereas the adjusted neonatal composite outcome did not.
Our study of the morbidity of primary cesarean delivery in the first and second stage of labor showed marginally increased maternal but not neonatal morbidity in those women who underwent cesarean delivery in the second stage of labor. We observed slightly longer operating times and an increased, albeit uncommon, risk of cystotomy, suggesting that cesarean delivery in the second stage of labor may be more technically difficult. This is likely due to engagement of the fetal head in the pelvis, the difficulty in delineating the bladder, and the larger infants that are perhaps more difficult to remove from the uterus. The incidence of uterine atony in second stage cesareans also increased and we speculate that this may be attributable to longer labor and uterine fatigue. We also found fetal injury to be more common in those women who underwent second stage cesarean delivery; however, the neonatal composite outcome was unaffected even after adjustment for group characteristics. This finding was recently reported in a study of fetal injury and where fetal injury was shown to be most common in those procedures done under the most pressing clinical circumstances such as cesarean delivery for fetal distress.6
Cesarean delivery for dystocia is justified by finding abnormalities in labor, most of which occur late in its course. Our study was designed to identify maternal or fetal morbidity, if any, that might be sustained if cesarean delivery were performed late in labor, specifically the second stage. Older studies have identified adverse fetal outcome when the second stage of labor is abnormally long.7–9 Indeed current management guidelines for the acceptable duration of the second stage are based on these older studies.10 Our study found no differences in a composite infant outcome after adjusting for confounders when cesarean delivery is performed in the second stage of labor compared with the first. Although fetal injury was more common when cesarean delivery was performed in the second stage of labor, this was uncommon and as previously reported, is most often associated with the conditions leading to the cesarean delivery rather than the surgery per se. Maternal morbidity, specifically uterine atony, T or J uterine incision extension, and cystotomy, was more common in women undergoing cesarean in the second stage, but it was minimally so, affecting an additional two of every 100 women. These findings suggest that a trial of labor that extends into the second stage does not in and of itself place the pregnancy at increased risk for adverse outcome. Thus, attempts at achieving an adequate trial of labor should not be prematurely abandoned due to concern about maternal or neonatal morbidity in the second stage.
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In addition to the authors, other members of the National Institute of Child Health and Human Development Maternal–Fetal Medicine Units Network are as follows:
University of Texas Southwestern Medical Center, Dallas, TX—S. Bloom, J. Gold, D. Bradford; University of Alabama at Birmingham, Birmingham, AL—J. Hauth A. Northen, S. Tate; Ohio State University, Columbus, OH—J. Iams, F. Johnson, S. Meadows, H. Walker; University of Utah, Salt Lake City, UT—M. Belfort, F. Porter, B. Oshiro, K. Anderson, A. Guzman; University of Chicago, Chicago, IL—J. Hibbard, P. Jones, M. Ramos-Brinson, M. Moran, D. Scott; 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. Steffy; University of Cincinnati, Cincinnati, OH—T. Siddiqi, H. How, N. Elder; 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—D. Conway, S. Barker, M. Rodriguez; The George Washington University Biostatistics Center, Washington, DC—E. Thom, H. Juliussen-Stevenson, M. Fischer; and National Institute of Child Health and Human Development—D. McNellis, K. Howell, S. Pagliaro. Cited Here...
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