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ORIGINAL RESEARCH |
From Department of Obstetrics and Gynecology, Saint Louis University, St. Mary’s Health Center, St. Louis, Missouri; and Department of Obstetrics and Gynecology, Texas Tech Health Sciences Center, Amarillo, Texas.
Address reprint requests to: Thomas D. Myles, MD, Saint Louis University, Department of Obstetrics and Gynecology, St. Mary’s Health Center, 6420 Clayton Road, Suite 559, St. Louis, MO 63117; E-mail: mylesth{at}slucare1.sluh.edu.
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ABSTRACT |
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METHODS: We reviewed all 7818 patients who delivered at the University of Illinois at Chicago from 1996 to 1999. Excluding nonvertex and multiple gestations, 6791 reached the second stage. Group 1 (n = 6259) consisted of patients with a second stage of 120 minutes or less; group 2, greater than 120 minutes (n = 532 [7.8%]); group 2A, 121–240 minutes (n = 384 [5.7%]); and group 2B, greater than 240 minutes (n = 148 [2.2%]). We compared pregnancy outcomes for these groups with respect to maternal and neonatal morbidity factors using 
2, Student t, and Wilcoxon rank-sum tests (significance, P < .05).
RESULTS: Vaginal delivery rates were 98.7% (group 1), 84.0% (group 2), 90.2% (group 2A), and 65.5% (group 2B). Group 2 had higher rates of perineal trauma, episiotomy usage, chorioamnionitis, postpartum hemorrhage, and operative vaginal delivery than group 1 (P < .001, all comparisons). Group 2B had higher rates of episiotomy usage, operative vaginal deliveries, and perineal trauma than group 2A (P < .001, all comparisons). The neonatal morbidity rates were similar for the three groups. Diabetes, preeclampsia (P < .023), macrosomia, nulliparity, chorioamnionitis, oxytocin usage, and labor induction were each independently associated with an increased risk of a prolonged second stage (all but preeclampsia, P < .001).
CONCLUSION: A prolonged second stage is associated with a high rate of vaginal delivery, but a high rate of maternal, though not neonatal, morbidity was observed. Certain antenatal and intrapartum conditions are associated with a prolonged second stage of labor.
Hamilton arbitrarily defined a second stage of labor longer than 120 minutes as prolonged.1 Recently Menticoglou et al2 reported that up to 11% of nulliparous patients could have a second stage of labor lasting longer than 3 hours and that the majority of these women delivered vaginally. Maternal risk factors described for a prolonged second stage include nulliparity, use of epidural analgesia, oxytocin usage, length of the active phase of labor, total maternal weight gain, fetal weight, and occiput posterior presentation.3–5
In 1952, Hellman and Prystowsky6 reported an increase in infant mortality when the second stage exceeded 150 minutes. Continuous improvements in fetal monitoring and neonatal care have alleviated previous concerns related to the effect of a prolonged second stage of labor on neonatal metabolic status and infant mortality. Several authors have reported that no differences exist for umbilical artery pH, 5-minute Apgar scores, and neonatal intensive care unit (NICU) admissions for infants delivered under tocographic monitoring with a prolonged second stage of labor.3,4,7 However, studies2–9 evaluating these neonatal morbidities did not separate or evaluate neonates delivered after an extremely prolonged second stage of labor (greater than 240 minutes).
In 1920, DeLee10 suggested that application of forceps should be considered when prolonged second stage of labor is diagnosed. Currently, maternal complications due to prolonged second stage of labor include postpartum complications such as hemorrhage, fever, and infection.7,8 Patients with a prolonged second stage also undergo an increased number of instrumental deliveries.2,4,5,8 Information regarding other maternal morbidities or complications have not been well described.2–9
Our purpose here is to evaluate both the maternal and neonatal outcomes or morbidities of pregnancies with a prolonged second stage of labor (greater than 120 minutes). We also evaluate for antenatal–intrapartum risk factors as well as medical complications that may be associated with a prolonged second stage of labor.
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MATERIALS AND METHODS |
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Recorded maternal information included age, race, parity, gestational age at delivery, preterm delivery (less than 37 weeks), diabetes (gestational and preexisting), preeclampsia, chorioamnionitis (defined as two temperatures above 38C [100.4F] requiring antibiotic treatment), usage of oxytocin, labor epidural, induction of labor, meconium-stained amniotic fluid, postpartum hemorrhage (estimated blood loss greater than 500 mL for a vaginal delivery and greater than 1000 mL for a cesarean delivery), mode of delivery, operative vaginal delivery, cesarean delivery indication (as documented by the attending physician), episiotomy, and perineal trauma (third or fourth degree lacerations).
Neonatal factors investigated included gender, birth weight, macrosomia (defined as a birth weight greater than 4000 g), 5-minute Apgar score, umbilical artery pH, NICU admission, hospital length of stay, and perinatal death. Hospital policy required obtaining umbilical cord gases with all cesarean or operative vaginal deliveries as well as deliveries of infants with low Apgar scores. Additional studies were done at the discretion of the attending physician. Patients who had an intrauterine fetal demise before the second stage of labor or an infant with a lethal congenital anomaly were not included in the perinatal mortality analysis.
With SPSS 9.0 (SPSS Inc., Chicago, IL), we compared the groups (and subgroups) using Student t tests, Wilcoxon rank-sum tests, 2 tests, and multivariable analysis as appropriate. Odds ratios (ORs) were also calculated for several comparisons. The nonparametric tests noted above were used for the noncontinuous data. Separate comparisons were also made with respect to several subgroups including multiparous, nulliparous, term, and preterm patients as well as mode of delivery to confirm the validity of combining all of the data. Significance for all tests was set at P < .05.
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RESULTS |
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Tables 1
and 2 depict the comparisons of the maternal and neonatal data for group 1 (n = 6259) and group 2 (n = 532) patients. All significant findings remained significant after multivariable analysis. The separate evaluations (for each comparison) of term, preterm, nulliparous, and multiparous patients did not affect the results unless specified within the text. The percentage of each type of care provider (midwife, resident, or attending physician) did not differ by group (1, 2, 2A, or 2B). The ethnic diversity of our obstetric population was essentially evenly distributed across groups. Patients who identified themselves as white were more likely to have a prolonged second stage of labor (P < .001).
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On average, diabetic patients had longer second stages of labor (50.7 minutes versus 38.7 minutes, P < .009). More diabetic patients had prolonged second stages (OR 1.8; confidence interval [CI] 1.3, 2.5). The increased risk of a prolonged second stage in diabetic patients was independent of both birth weight and macrosomia. Macrosomia was associated with a prolonged second stage of labor (OR 2.5; CI 1.9, 3.4; P < .001).
Second-stage durations were 51.6 minutes and 38.9 minutes for patients with preeclampsia and nonpre-eclamptics, respectively (P < .01). All laboring patients diagnosed with preeclampsia before delivery were given magnesium sulfate. Preeclamptic patients were more likely to have a prolonged second stage (OR 1.5; CI 1.04, 2.2; P < .023). Significance for preeclampsia’s association with a prolonged second stage of labor remained for term patients only after controlling for the other significant factors.
Patients with chorioamnionitis had longer second stages (91.6 minutes, versus 37.9 minutes for no chorioamnionitis, P < .001). Their OR for a prolonged second stage was 4.9 (CI 3.5, 6.9). After subgroup analysis, significance remained only for the term patients (OR 6.2; CI 4.3, 9.0). Oxytocin (OR 2.3; CI 1.9, 2.8) and labor induction (OR 1.6; CI 1.3, 2.0) were also observed to be independent risk factors for a prolonged second stage of labor. These two associations were only observed in the term patients (P < .001, both variables).
Patients delivering male infants experienced longer second stages (41.3 minutes versus 37.7 minutes, P < .016). The male-associated prolonged second stage of labor was present only in the term patients (OR 1.3; CI 1.1, 1.6; P < .005). However, significance was lost when this factor was corrected for the presence or absence of macrosomia.
With regard to maternal morbidity, the risk for perineal trauma was increased regardless of whether an episiotomy had been performed on the group 2 patients. The increased risk of postpartum hemorrhage remained significant only for the term group 2 patients; preterm patients did not have an increased risk for postpartum hemorrhage.
Neonatal outcomes (Table 2
) were similar for groups 1 and 2 irrespective of delivery mode. No differences were seen when comparing groups 1 and 2 with respect to cord pH less than either 7.00 or 7.20. Slightly more term infants from group 2 were admitted to the NICU (2.2% versus 1.1%, P < .032); however, there was no significant difference in the frequency of prolonged hospital stay.
Comparisons between group 2A (second stage 121–240 minutes, n = 384) and group 2B (second stage of labor greater than 240 minutes, n = 148) are in Tables 3 and 4; significant values remained significant after multivariable analysis. Significant differences between each of these groups and group 1 are noted where applicable. The separate evaluations of term, preterm, nulliparous, and multiparous patients did not affect the results unless specified within the text. Only the term group 2B patients had an increased risk for an operative vaginal delivery when compared with group 2A.
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No significant differences were seen between groups 2A and 2B with respect to preeclampsia, diabetes, nulliparity, oxytocin usage, labor induction, preterm delivery, and a history of preterm delivery, whereas we noted macrosomia to be a risk factor for a very prolonged second stage (2A versus 2B; OR 2.2; CI 1.3, 3.8). Groups 2A and 2B both differed significantly from group 1 for all of these variables. However, the significant differences seen between both groups 2A and 2B and the patients in group 1 for both oxytocin usage and labor induction remained only for the term patients (all Ps < .001).
With respect to maternal morbidity, the group 2B patients who did not have an episiotomy had a greater frequency of perineal trauma than similar group 2A patients (group 2B, 16.2%, versus group 2A, 6.5%; P < .03). The combination of group 2B and an operative vaginal delivery was associated with the greatest risk for perineal trauma (40.4% versus group 2A, 24.0%; P < .02). The risk for significant perineal trauma in patients with a spontaneous vaginal delivery increased with the length of the second stage of labor (group 1, 6%; group 2A, 9.2%; group 2B, 12.2%; P < .001).
With respect to neonatal morbidities (Table 4), there were no differences observed for the infants in group 2B (when compared with either group 1 or group 2A) with respect to term NICU admission, Apgar scores less than 7, umbilical artery pH less than either 7.20 or 7.00, or hospital length of stay. There were also no differences when group 1 was compared with group 2A for each of these potential neonatal morbidities. The increased risk of shoulder dystocia observed in group 2B relative to group 1 was noted to be significant only in the multiparous subset (13.6% versus 0.0%, P < .001).
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DISCUSSION |
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This observational study presents information regarding intrapartum outcomes for patients with prolonged (more than 120 minutes) and very prolonged (more than 240 minutes) second stages. For the purpose of this work we performed a MEDLINE (PubMed) review of the literature from 1966 to 2002 (English and French) to identify previously reported maternal risk factors as well as maternal–neonatal complications associated with a prolonged second stage of labor (key words: "second stage of labor," "prolonged second stage," risk factors [including "diabetes" and "preeclampsia"], and "second stage complications"). Based upon our search, little is written on the subset of patients delivering beyond 4 hours in terms of either risk factors (for such a prolonged second stage) or maternal morbidity. Our separation of these patients into a distinct group allows for identification of their increased maternal morbidity. Maternal morbidity increased as the second stage increased beyond 2 hours and increased further beyond 4 hours. Based upon our findings, the group of patients at risk for a very prolonged second stage (more than 240 minutes) differs little from those at risk for a second stage of 121–240 minutes. Our identified risk factors for a prolonged second stage include nulliparity, preeclampsia, diabetes (any type), macrosomia, male infant, labor epidural, labor induction, oxytocin usage, and chorioamnionitis. Of these factors, only labor epidural and fetal macrosomia were associated with an increased risk for a very prolonged second stage.
Our analysis indicates an increased risk for maternal morbidity when there is a prolonged second stage of labor. This risk appears to be related to the actual length of the second stage. The higher rates of perineal trauma,9 instrumental delivery,2,4,5,9 and postpartum hemorrhage7–9 noted in our study confirm previous reports. Contrary to these reports, Kuo et al5 identified no increased risk for postpartum hemorrhage or severe perineal lacerations. The increased frequency of episiotomy usage for the patients with a prolonged second stage of labor seen in our study was not described in these other studies.2–9 In addition, these studies2,4,5,7–9 did not break down the length of the second stage into subsets so as to separately evaluate patients with a very prolonged second stage of labor. Furthermore, corrections for delivery type or episiotomy use are not present in the studies that discussed the above-mentioned maternal morbidities.2,4,5,7–9 The higher risk for perineal lacerations in the patients with a very prolonged second stage of labor is likely primarily due to time. Support of this explanation is provided by both de Leeuw et al11 and Donnelly et al.12 These authors noted that the length of the second stage was directly related to the occurrence of significant perineal lacerations, but neither presented data beyond 120 minutes.
We observed, as did others,6–8 that a higher rate of chorioamnionitis was associated with a prolonged second stage. Kuo et al5 found no increased risk for puerperal fever for patients with a second stage of over 120 minutes. A controlled trial to address the need for prophylactic antibiotics during a prolonged second stage is needed.
Our observed risks for maternal morbidity remained significant regardless of nulliparity, term or preterm delivery, and mode of delivery. With the exception of postpartum hemorrhage, each of these complications was observed with an even greater frequency when the second stage went beyond 4 hours. Postpartum hemorrhage has been associated with both high birth weight and operative vaginal delivery,5,6,8,9 which are observed to occur in our patients with a prolonged second stage of labor. Although we did not evaluate the need for blood transfusions, our rate of postpartum hemorrhage is similar to that observed by Saunders et al.8
With respect to neonatal outcome, our findings were in agreement with previous reports.2,4,5,7–9 However, these studies did not separate out the pregnancies with a very prolonged second stage (greater than 240 minutes). This study provides additional information regarding neonatal outcome by virtue of the separation of the prolonged second stage of labor into two groups (121–240 minutes and greater than 240 minutes). No significant differences were seen between any of the second stage lengths and 5-minute Apgar scores less than 7 or umbilical artery pHs less than 7.00 or 7.20 regardless of term or preterm delivery, nulliparity or multiparity, or mode of delivery. As cord pHs were not obtained uniformly, it is possible that differences could occur. However, the percentages of patients having cord gases obtained were similar for groups 1, 2A, and 2B. Slightly more term infants born to our mothers with a prolonged second stage of labor were admitted to the NICU. The clinical importance of this is likely negligible, as the frequency of prolonged hospital stays did not differ. The slightly lower pH noted is consistent with the findings of Katz et al.13 They noted pH to decrease with time (second stage 0–120 minutes). The higher frequency of a prolonged second stage of labor in patients delivering either a male or a large infant also confirms previous reports.14
Our study also shows that certain preexisting maternal and intrapartum risk factors are associated with a prolonged second stage of labor. We observed that diabetes, preeclampsia, and chorioamnionitis were each independently associated with a prolonged second stage of labor. Based on our MEDLINE searches,2–9 none of the studies we identified reported these to be risk factors for a prolonged second stage of labor. Our observations of nulliparity, oxytocin usage, labor induction, and macrosomia as independent risk factors for a prolonged second stage confirm other studies’ results.3–5,14 The identification of macrosomia as an independent risk factor for a very prolonged second stage of labor was not reported in these studies, as they did not separately evaluate the patients with a second stage of labor greater than 240 minutes.
Macrosomia and dystocia are seen more frequently with diabetics.15,16 Xiong et al17 noted that preeclamptics had an increased frequency of large for gestational age infants. Our observation (for preeclamptics) is in agreement with the finding of Edwards and Witter,18 who also noted an increased length of the second stage of labor for their preeclamptic patients; however, they did not evaluate for a prolonged second stage. Although Satin et al19 noted an increased incidence of dystocia in patients who had chorioamnionitis diagnosed after the infusion of oxytocin, the occurrence of a prolonged second stage was not discussed in their article.
Using our data, an arbitrary cesarean delivery at 120 minutes (as suggested by current obstetric dogma5,7) would have led to 405 extra cesarean deliveries and raised the cesarean delivery rate of the entire group from 2.4% to 9.0%. Delaying routine cesarean delivery until 240 minutes would have raised the cesarean delivery rate to 3.8%. However, because the increased maternal morbidity that we observed can potentially have long-term effects,12,20 obstetricians should be very cautious in allowing the second stage to progress beyond 4 hours. Using this 4-hour cutoff would have only increased our overall cesarean delivery by 1.2%.
A potential limitation of this study is its retrospective design. An ideal study would allow for the randomization of patients with a prolonged second stage into two or three groups (cesarean, operative vaginal, expectant management). This would be exceedingly difficult for most centers. The large number of patients in our study likely lessens this limitation. Another potential limitation to our study is the unavailability of long-term follow-up for the neonates delivered after a prolonged second stage of labor. If infants developed problems after discharge, this could not be identified. Only the postnatal courses for the infants admitted to the NICU could be evaluated.
In conclusion, a prolonged second stage of up to 4 hours is associated with a 90.8% vaginal delivery rate. Patients with diabetes, chorioamnionitis, preeclampsia, oxytocin usage, labor induction, macrosomia, and nulliparity are all at an increased risk for a prolonged second stage. Physicians should consider informing their patients who have a second stage longer than 2 hours that an operative vaginal delivery may be required in approximately 21% of cases and that up to 16% of cases could result in severe perineal trauma. Because of these risks and the potential for shoulder dystocia observed beyond 240 minutes, the delivering physician should be prepared for these events at the time of delivery.
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Footnotes |
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Received October 4, 2002. Received in revised form January 31, 2003. Accepted February 27, 2003.
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REFERENCES |
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2. Menticoglou SM, Mannin F, Harman C, Morrison I. Perinatal outcome in relation to second-stage duration. Am J Obstet Gynecol 1995;173:906–12.[Medline]
3. Piper JM, Bolling DR, Newton ER. The second stage of labor: Factors influencing duration. Am J Obstet Gynecol 1991;165:976–9.[Medline]
4. Moon JM, Smith CV, Rayburn WF. Perinatal outcome after a prolonged second stage of labor. J Reprod Med 1990;35:229–31.[Medline]
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6. Hellman LM, Prystowsky H. The duration of the second stage of labor. Am J Obstet Gynecol 1952;63:1223–33.
7. Cohen WR. Influence of the duration of second stage labor on perinatal outcome and puerperal morbidity. Obstet Gynecol 1977;49:266–9.
8. Saunders NG, Paterson CM, Wadsworth J. Neonatal and maternal morbidity in relation to the length of the second stage of labour. Br J Obstet Gynaecol 1992;99:381–5.[Medline]
9. Gerber S, Vial Y, Hohlfeld P. Pronostic maternal et neonatal lors d’une deuxieme phase d’scouchement prolongee. J Gynecol Obstet Biol Reprod 1999;28:145–50.[Medline]
10. DeLee JB. The prophylactic forceps operation. Am J Obstet Gynecol 1920;1:34–44.
11. de Leeuw JW, Struijk PC, Vierhout ME, Wallenburg HCS. Risk factors for third degree perineal ruptures during delivery. Br J Obstet Gynaecol 2001;108:383–7.
12. Donnelly V, Fynes M, Campbell D, Johnson H, O’Connell R, O’Herlihy C. Obstetrics events leading to anal sphincter damage. Obstet Gynecol 1998;92:955–61.[Abstract]
13. Katz M, Lunenfeld E, Meizner I, Bashan N, Gross J. The effect of the duration of the second stage of labour on the acid-base state of the fetus. Br J Obstet Gynaecol 1987;94: 425–30.[Medline]
14. Lieberman E, Lang JM, Cohen AP, Frigoletto FD, Acker D, Rao R. The association of fetal sex with the rate of cesarean section. Am J Obstet Gynecol 1997;176:667–71.[Medline]
15. Weeks JW, Major CA, de Veciana M, Morgan MA. Gestational diabetes: Does the presence of risk factors influence perinatal outcome? Am J Obstet Gynecol 1994; 171:1003–7.[Medline]
16. Casey BM, Lucas MJ, Mcintire DD, Leveno KJ. Pregnancy outcomes in women with gestational diabetes compared with the general obstetric population. Obstet Gynecol 1997;90:869–73.[Abstract]
17. Xiong X, Demianczuk NN, Buckners P, Saunders LD. Association of preeclampsia with high birth weight for gestational age. Am J Obstet Gynecol 2000;183:148–55.[Medline]
18. Edwards C, Witter FR. Preeclampsia, labor duration and mode of delivery. Int J Gynaecol Obstet 1997;57:39–42.[Medline]
19. Satin AJ, Maberry MC, Leveno DJ, Sherman L, Kline DM. Chorioamnionitis: A harbinger of dystocia. Obstet Gynecol 1992;79:913–5.
20. Allen RE, Hosker GL, Smith ARB, Warrell DW. Pelvic floor damage and childbirth: A neurophysiological study. Br J Obstet Gynaecol 1990;97:770–7.[Medline]
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