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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2. Murphy DJ. Failure to progress in the second stage of labour. Curr Opin Obstet Gynecol 2001;13:557–61.
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6. Alexander JM, Leveno KJ, Hauth J, Landon MB, Thom E, Spong CY, et al. Fetal injury associated with cesarean delivery. Obstet Gynecol 2006;108:885–90.
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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.