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Obstetrics & Gynecology 2002;99:731-739
© 2002 by The American College of Obstetricians and Gynecologists
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ORIGINAL RESEARCH

Changing Obstetric Practices Associated With Decreasing Incidence of Meconium Aspiration Syndrome

Bradley A. Yoder, MD, Erica A. Kirsch, MD, William H. Barth, Jr, MD and Michael C. Gordon, MD

From the Departments of Pediatrics and Obstetrics/Gynecology, Wilford Hall Medical Center, Lackland AFB, Texas.

Address reprint requests to: Bradley A. Yoder, MD, University of Texas Health Science Center at San Antonio, Department of Pathology, Room 321-E, 7703 Floyd Curl Drive, San Antonio, TX 78284; E-mail: yoder{at}pathology.uthscsa.edu.


   ABSTRACT
TOP
ABSTRACT
MATERIALS AND METHODS
 RESULTS
 DISCUSSION
 REFERENCES
 
OBJECTIVE: To describe changes in neonatal and obstetric practices that may have contributed to the decreasing incidence of meconium aspiration syndrome in our population during this time.

METHODS: We compared neonatal and obstetric characteristics of 61 infants diagnosed with meconium aspiration syndrome with 1365 infants born through moderate or thick meconium-stained amniotic fluid at more than 37 weeks’ completed gestation. Data were prospectively collected, and all respiratory diagnoses were concurrently made. Three distinct birth year groups were analyzed based on changing obstetric practice paradigms.

RESULTS: Meconium aspiration syndrome decreased nearly four-fold from 1990–1992 to 1997–1998 (5.8% to 1.5% of meconium-stained infants more than 37 weeks;P < .003).The only change in neonatal characteristics was a 33% decrease in births more than 41 weeks with a reciprocal 33% increase in births 38–39 weeks during 1997–1998. Significant changes in obstetric practice included more frequent diagnosis of nonreassuring fetal heart rate patterns, greater use of amnioinfusion, and increased cesarean delivery rate in 1997–1998. By logistic regression analysis, the only consistent risk factor for meconium aspiration syndrome across all three epochs was the presence of tracheal meconium.

CONCLUSION: Reduction in post-term delivery was the most important factor in reducing meconium aspiration syndrome.

Meconium aspiration syndrome is the leading cause of respiratory failure in term infants, affecting up to 5% of all infants born through meconium-stained amniotic fluid.1–5 Severe pulmonary dysfunction occurs in about one-half of the infants diagnosed with meconium aspiration syndrome, but the risk for death or need for extra-corporeal membrane oxygenation has decreased dramatically over the past decade.4–7 Advances in the postnatal management of meconium aspiration syndrome, such as low tidal volume ventilation (conventional and high frequency), surfactant replacement, and inhaled nitric oxide therapy may be important factors in this decline.8–11 Alternatively, changes in obstetric care such as amnioinfusion may have contributed to decreased severity of disease.12–15

Early recognition of infants at highest risk for meconium aspiration syndrome could be beneficial for optimizing the study of intrapartum and postnatal therapeutic modalities. A number of intrapartum risk factors have been identified for meconium aspiration syndrome, but a sensitive and specific tool for prediction of risk has not been successfully developed.4,16–25 In a prior report, we identified several important intrapartum and immediate postnatal risk factors for meconium aspiration syndrome.5 In a pilot study, we used data from that report to develop a delivery room model to predict infants at high risk for severe meconium aspiration syndrome.

We initiated a prospective study in all infants born through meconium-stained amniotic fluid to test the accuracy of this model to discriminate low and high risk for meconium aspiration syndrome. During the time of this study (1997–1998), we identified a significant reduction in the incidence of meconium aspiration syndrome in our population compared with the epoch in which we developed our model. This decrease severely limited our ability to test the model. As there had been no apparent change in the pediatric approach to infants born through meconium-stained fluid over the past decade in our center, we hypothesized that changes in obstetric management may have contributed to the noted decline. The purpose of this report is to describe changes in obstetric practice over the past several years that may have contributed to the decreasing incidence of meconium aspiration syndrome in our population.


   MATERIALS AND METHODS
TOP
ABSTRACT
 MATERIALS AND METHODS
RESULTS
 DISCUSSION
 REFERENCES
 
The study population consisted of all live infants greater than 37 weeks’ completed gestation born through meconium-stained amniotic fluid at Wilford Hall Medical Center from January 1, 1990, through December 31, 1998. Two trained nurses collected data for all births on standardized data sheets from the time of delivery. Maternal antepartum and intrapartum records were reviewed immediately after delivery. Neonatal data were prospectively recorded until discharge from the hospital. All clinical diagnoses, especially pulmonary complications, were concurrently monitored. Infants admitted to the newborn intensive care unit were monitored for details related to cardiopulmonary support, including duration of oxygen and mechanical ventilator support, and the use of other therapeutic modalities including surfactant replacement, high-frequency ventilation, inhaled nitric oxide therapy, and extracorporeal membrane oxygenation. All data were entered into a single database. Data were verified at the time of entry and reviewed on a monthly basis. Data on all infants admitted to the newborn intensive care unit were also cross-referenced to a separate database for that unit.

Antepartum complications coded in the database included maternal diabetes, fetal growth restriction, preeclampsia, oligohydramnios, and prolonged premature rupture of membranes. Several intrapartum characteristics were also recorded including the occurrence of a variety of nonreassuring fetal heart rate (FHR) patterns, mode of delivery, presumed chorioamnionitis, appearance of the amniotic fluid, and the use of amnioinfusion. Amniotic fluid was characterized by the obstetric provider as light, moderate, or thick as previously reported.5 In cases where the appearance of the amniotic fluid changed during the labor process, the thickest appearance was recorded.

Management of the neonate immediately after birth was monitored and recorded. Since January 1990, our center has employed a selective approach to the airway management of infants with meconium-stained fluid.5 Infants with clear amniotic fluid were managed without tracheal suctioning. The obstetrician routinely suctioned the oral and nasopharyngeal airway of any fetus exposed to meconium-stained fluid before delivery of the shoulder and thorax. After delivery, infants with light meconium-stained fluid were managed similar to infants with clear amniotic fluid. Postdelivery neonatal management of infants born through moderate or thick meconium-stained fluid was based on the infant’s condition immediately after birth. Infants with good tone, respiratory effort, and cry did not receive routine laryngoscopy or tracheal suctioning. Depressed infants had laryngoscopy performed. Suction was applied through either an endotracheal tube or a 10-F suction catheter with wall suction of at least 100 mmHg. Use of assisted ventilation by bag mask or via endotracheal tube was applied as needed following the guidelines of the American Academy of Pediatrics/American Heart Association Neonatal Resuscitation Program.

All pulmonary diagnoses were prospectively defined. Meconium aspiration syndrome was defined by the following: 1) presence of meconium-stained amniotic fluid; 2) tachypnea, retractions, grunting, or other abnormal signs on physical examination consistent with pulmonary disease; 3) need for supplemental oxygen or ventilator support; 4) a compatible chest radiograph; and 5) low suspicion for infection. Diagnostic criteria for other neonatal respiratory diseases including pneumonia, transient tachypnea of the newborn, pulmonary hypertension, and air leak have been previously published.5

To estimate the influence of changing care practices over the study period, three subgroups were identified. Group 1 comprised infants born from 1990 through 1992. Amnioinfusion was not used during this time period, and the institutional cesarean delivery rate was less than 10% (Table 1Go). Group 2 included those infants born in the transition period from 1993 through 1996. In early 1993, we adopted a risk factor-based policy for the prevention of early onset neonatal Group B Streptococcal sepsis as recommended by the ACOG.26 During this time, any patient with a prior affected newborn, any colony count Group B Streptococcal bacteruria, a gestational age less than 37 weeks, intrapartum fever to 100.4F, or rupture of membranes greater than 18 hours received intrapartum antibiotic prophylaxis with either penicillin or ampicillin. Amnioinfusion was used in less than 5% of labors with meconium-stained fluid, and the cesarean delivery rate was 13%. Group 3 comprised infants born in the years 1997 and 1998. During this time, we attempted to study our predictive model for meconium aspiration syndrome and noted a marked decrease in meconium aspiration syndrome incidence. Also during this time period, amnioinfusion was used in over 35% of labors with moderate or thick meconium-stained fluid, and the institutional cesarean delivery rate increased to 15%. Before 1997, antepartum fetal surveillance for women reaching 41 completed weeks’ gestation included a single nonstress test. In 1997, we adopted a policy of twice-weekly fetal nonstress tests and weekly assessments of amniotic fluid volume with ultrasound in this group. Oligohydramnios (amniotic fluid index less than 5) was considered an indication for induction of labor.


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  		Table 1. Changing Institutional Obstetric Practice Patterns Among All Deliveries by Birth Year Study Group
 
The primary outcome variable was the diagnosis of meconium aspiration syndrome. Bivariate analyses comparing differences between infants with meconium aspiration syndrome with those without were performed by two-tailed t test, {chi}2, and Fisher exact test. To evaluate the effect of birth year on outcomes and practices, Mantel-Haenszel {chi}2 was used to compare differences in categoric variables with respect to the three study subgroups, continuous data were compared by one-way analysis of variance, and ordinal measures were compared using Kruskal-Wallis test. Stepwise logistic regression was subsequently used to test for independent risk factors on the occurrence of meconium aspiration syndrome, with Hosmer-Lemeshow goodness-of-fit determination.27 All statistical procedures were performed using SPSS for Windows, 9.0 (SPSS Inc., Chicago, IL). This study was approved by the medical center Institutional Review Committee. Based on the observational nature of the study, informed consent was determined to not be necessary.


   RESULTS
TOP
ABSTRACT
 MATERIALS AND METHODS
 RESULTS
DISCUSSION
 REFERENCES
 
During the study period, 2240 (17.3%) of 12,935 live births more than 37 weeks’ gestation were exposed to meconium-stained amniotic fluid. Meconium aspiration syndrome was diagnosed in 61 (2.7%) infants. Mechanical ventilation was applied to 27 (44%) of the 61 infants with meconium aspiration syndrome. Among infants born through moderate or thick meconium-stained fluid, there was a trend toward lower rates of mechanical ventilation for any reason by birth year study groups (1990–1992 = 13 of 449 versus 1993–1996 = 21 of 581 versus 1997–1998 = five of 396, P = .61), as well as mechanical ventilation for meconium aspiration syndrome (1990–1992 = seven of 449 versus 1993–1996 = 14 of 581 versus 1997–1998 = three of 396, P = .12). There were no deaths caused by meconium aspiration syndrome, and one infant was managed with extracorporeal membrane oxygenation. No infants with meconium aspiration syndrome were transported from our unit to another newborn intensive care unit for supportive care. Meconium aspiration syndrome occurred only among infants with moderate or thick meconium-stained fluid (n = 1426). We found that the incidence of meconium aspiration syndrome significantly decreased over the years of study from 1990 through 1998 (Figure 1Go). Although the incidence appeared to first decline in 1995, the most dramatic decrease occurred in 1997 and 1998. In addition to the decreased incidence of meconium aspiration syndrome, we noted significant (P < .001) birth year-related reductions in the diagnosis of pneumonia (1990–1992 = 6.9% versus 1993–1996 = 3.1% versus 1997–1998 = 2.5%, P < .001) and of any respiratory diagnosis (1990–1992 = 16.5% versus 1993–1996 = 10.7% versus 1997–1998 = 6.6%, P < .001). There were no differences over time in the diagnoses of pulmonary hypertension, transient tachypnea of the newborn, pneumothorax, respiratory distress syndrome, or lung hypoplasia syndromes. As expected, the incidence of meconium aspiration syndrome increased for each week of gestation from 38 through 42 weeks (Figure 2Go).



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  		Figure 1. Incidence of meconium aspiration syndrome by year of birth from 1990 through 1998. P = .003 by Mantel-Haenszel {chi}2.

Yoder. Obstetric Practices and Meconium Aspiration Syndrome. Obstet Gynecol 2002.

 


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  		Figure 2. Effect of gestational age on the incidence of meconium aspiration syndrome. Births 1990–1998. P < .001 by Mantel-Haenszel {chi}2.

Yoder. Obstetric Practices and Meconium Aspiration Syndrome. Obstet Gynecol 2002.

 
Table 2Go compares the antepartum and intrapartum characteristics of infants born through moderate or thick meconium-stained fluid by diagnosis of meconium aspiration syndrome. Oligohydramnios, need for cesarean delivery, and a variety of nonreassuring FHR patterns were significantly more common among infants diagnosed with meconium aspiration syndrome (P < .001). Use of amnioinfusion was not different between infants with meconium aspiration syndrome and those without. The presence of meconium in tracheal aspirates, low Apgar scores, low arterial cord pH, and the need for resuscitative intervention were significantly more frequent among infants diagnosed with meconium aspiration syndrome as shown in Table 3Go.


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  		Table 2. Antepartum and Intrapartum Characteristics of Infants Delivered Through Moderate or Thick Meconium-Stained Amniotic Fluid by Diagnosis of Meconium Aspiration Syndrome
 

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  		Table 3. Delivery Room and Postnatal Characteristics of Infants Delivered Through Moderate or Thick Meconium-Stained Amniotic Fluid and the Diagnosis of Meconium Aspiration Syndrome
 
We analyzed the influence of the birth year on several antepartum, intrapartum, and neonatal risk factors for meconium aspiration syndrome. There were significant increases in the use of antenatal ultrasound, the diagnosis of chorioamnionitis, delivery by cesarean, and the use of amnioinfusion over the time of this study (data not shown). As shown in Table 4Go, these differences persisted in the subgroup of infants born through moderate or thick meconium-stained fluid. Other prenatal complications including diabetes, pregnancy-related hypertension, oligohydramnios, fetal growth restriction, and prolonged rupture of membranes were not different by birth year group. Marked differences in the identification of nonreassuring FHR patterns were also found between the birth year groups (Table 4Go). There was a three-fold increase in the overall diagnosis of any nonreassuring FHR pattern between 1990–1992 and 1997–1998. This difference was primarily due to an increase in the recognition of variable decelerations (1990–1992 = 13% versus 1997–1998 = 54%, P < .001), although intrapartum diagnosis of late decelerations and bradycardia also increased significantly between 1990–1992 and the other two birth year groups.


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  		Table 4. Influence of Birth Year Group on Maternal Antenatal Characteristics and FHR Patterns for Infants Delivered Through Moderate or Thick Meconium-Stained Amniotic Fluid
 
As shown in Table 5Go, the distribution of gestation shifted significantly over the years of study. The highest-risk group for meconium aspiration syndrome, infants born at 41 or more weeks’ gestation, decreased from over 40% in 1990–1992 to less than 28% by 1997–1998, a 33% reduction. There was a reciprocal 33% increase in the percentage of infants born in the lower-risk 38–39 weeks’ gestation over the same time span. The percent of infants with 5-minute Apgar scores less than 7 decreased with each proceeding birth year group but did not reach statistical significance. Birth year group differences were not found for other high-risk variables including need for advanced resuscitation, presence of meconium when the trachea was suctioned, and arterial cord pH.


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  		Table 5. Influence of Birth Year Group on Neonatal Characteristics for Infants Delivered Through Moderate or Thick Meconium-Stained Amniotic Fluid
 
Stepwise logistic regression revealed an independent association between several factors and the diagnosis of meconium aspiration syndrome (Table 6Go). The presence of meconium in the trachea (selective approach to tracheal suctioning) was the most important risk factor for meconium aspiration syndrome. A diagnosis of chorioamnionitis and increasing year of birth were the only variables associated with decreased risk for meconium aspiration syndrome. Regression analysis by the defined birth year groups clearly demonstrated that infants born through meconium-stained fluid in the two earlier birth year groups had significantly greater risk for meconium aspiration syndrome than infants born in 1997–1998. When regression analyses were performed within each birth year group, the only consistent independent predictor for meconium aspiration syndrome across all three birth year groups was the presence of tracheal meconium (Table 7Go).


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  		Table 6. Influence of Gestation and Birth Year Groups on Logistic Regression Analysis for Meconium Aspiration Syndrome in Infants Born Through Moderate or Thick Meconium-Stained Amniotic Fluid
 

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  		Table 7. Risk Factors for Meconium Aspiration Syndrome Among Infants Born Through Moderate or Thick Meconium-Stained Amniotic Fluid: Logistic Regression Analysis by Birth Year Study Group
 

   DISCUSSION
TOP
ABSTRACT
 MATERIALS AND METHODS
 RESULTS
 DISCUSSION
REFERENCES
 
Meconium aspiration syndrome is the most common cause of respiratory disease in the term infant. Previous large studies have reported rates of two to seven cases of meconium aspiration syndrome per 1000 live births.1,2,4 In the largest study to date, Wiswell et al reported on over 176,000 neonates born in military medical facilities from 1973 through 1987.2 Over this 15-year period, the incidence of meconium aspiration syndrome ranged between four to nine per 1000 live births and between 3–8% of all infants born through meconium-stained fluid. Our reported rates of four to eight per 1000 live births (or 5–6% of meconium-stained fluid births) between 1990–1996 are similar to those of Wiswell et al,2 suggesting the decreased incidence of meconium aspiration syndrome in 1997–1998 represents a real change.

Numerous studies have identified major risk factors associated with the diagnosis of meconium aspiration syndrome including nonreassuring FHR patterns, fetal acidosis, meconium in the trachea, cesarean delivery, and low Apgar scores.4,5,16–25 Our study confirms these as important risk factors for subsequent meconium aspiration syndrome. Despite the significant decrease in the incidence of meconium aspiration syndrome in our population, there were no identifiable differences in the commonly recognized neonatal risk factors for meconium aspiration syndrome over the time period studied. Specifically, the frequency of intratracheal meconium among suctioned infants was not different, rates of fetal acidosis were similar, and the need for delivery room resuscitation was unchanged. The frequency of low 1-and 5-minute Apgar scores was also similar. During the years of this study, there were no changes in obstetric or pediatric airway management of the infant at the time of delivery. Infants born through meconium-stained fluid routinely had the oronasopharynx suctioned by the obstetric provider before delivery of the shoulders or trunk. Throughout this study, a selective approach to tracheal suction of the newborn infant was applied as previously described.5 This approach has recently been confirmed in a large multicenter trial to not be associated with an increased risk of meconium aspiration syndrome.6 The only identifiable change in neonatal characteristics was a significant shift in estimated gestation at the time of birth. This difference may be critical given the fact that the highest rates for meconium aspiration syndrome in each birth year group occurred among infants born at 41 weeks’ gestation or more.

Over the past decade, we identified a number of important changes in institutional obstetric practice that could contribute to the decrease in meconium aspiration syndrome including the use of amnioinfusion, increased antenatal ultrasound application, more frequent clinical diagnosis of chorioamnionitis, increased epidural use, higher rates of cesarean delivery, and increased diagnosis of nonreassuring FHR patterns. Given the marked increase in the use of amnioinfusion between 1990–1992 and 1997–1998, we suspected that amnioinfusion might be a major factor in the decreasing incidence of meconium aspiration syndrome. However, we found no difference in the use of amnioinfusion and the subsequent diagnosis of meconium aspiration syndrome within either of the birth year groups where it was applied. These results are consistent with the report by Usta et al who found no difference in the incidence of meconium aspiration syndrome or other neonatal outcomes among 440 pregnancies managed with amnioinfusion versus 497 that were not.28 Although a recent meta-analysis on amnioinfusion evaluating a variety of small prospective trials suggests a beneficial effect from amnioinfusion, our data and those of Usta et al28 suggest that a large, prospective, multicenter study is still needed to evaluate the independent efficacy of amnioinfusion in the prevention of meconium aspiration syndrome.12–15,29,30

Another possible contributor to the decreased meconium aspiration syndrome rate was the more aggressive approach initiated in 1997 to assess fetal well-being during the third trimester. The significant decrease in mean gestational age and proportion of infants delivered at 41 weeks’ gestation or more during 1997–1998 suggests that this approach may have led to earlier identification and intervention of at-risk pregnancies. Unfortunately, data related to labor induction was not available in this study. Given the strong association of meconium aspiration syndrome with markers of intrapartum compromise, one would expect evidence for less fetal-neonatal compromise in the 1997–1998 birth year group.3 However, the rates for low arterial cord pH, need for bag mask resuscitation, low 1-minute Apgar scores, and presence of tracheal meconium were no different across the three birth year groups. Additionally, there were no differences for these factors between gestational age groups within each birth year group. Alternatively, the increased proportion of infants delivered before 41 weeks’ gestation could be related to the widespread use of early pregnancy ultrasounds.31 Logistic regression analysis within the birth year subgroups must be viewed cautiously because of the relatively small number of infants within each each subgroup diagnosed with meconium aspiration syndrome, particularly in 1997–1998. Additionally, the independent effect of each of these markers may be relatively weak given the high overall frequency of each relative to the low occurrence rate of meconium aspiration syndrome.

The difference in meconium aspiration syndrome over the course of this study might also be attributed to a change in the criteria used for the diagnosis of meconium aspiration syndrome. However, the same diagnostic criteria were applied throughout the 9-year period of this study, and all diagnostic criteria were applied concurrently by only one of the authors (BAY) on all study patients. The decreased rate for neonatal pneumonia suggests that the decreased incidence of meconium aspiration syndrome was not related to a shift in diagnostic patterns favoring pneumonia over meconium aspiration syndrome. The lack of any time-related differences in rates for other respiratory problems such as respiratory distress syndrome, transient tachypnea of the newborn, pneumothorax, or lung hypoplasia syndromes also suggests that the neonatal population was otherwise unchanged over the course of this study and that the decreased rate for meconium aspiration syndrome was a valid occurrence.

In summary, we identified a four-fold decrease in the rate of meconium aspiration syndrome over the last 2 years of a 9-year period from 1990 through 1998. Well-described neonatal risk factors for meconium aspiration syndrome were consistently present over the course of this study but were not associated with the decreased rate. Significant changes in obstetric practice associated with the decreased rate of meconium aspiration syndrome in this study included increased use of amnioinfusion, more frequent diagnosis of nonreassuring FHR patterns, higher cesarean delivery rates, near universal early antenatal ultrasound evaluation, and a significant decrease in the proportion of post-dates births. We cannot determine at this time whether a single variable, or the interaction of several of these variables in concert, may be responsible for the observed decrease in meconium aspiration syndrome. Given the relatively low rates of meconium aspiration syndrome, very large population studies will be needed to adequately evaluate this issue in the future.


   Footnotes
 
The views in this article are those of the authors and do not reflect the official policy of the Department of Defense or the US Government.

PII S0029-7844(02)01942-7

Received September 27, 2001. Received in revised form November 29, 2001. Accepted December 18, 2001.


   REFERENCES
TOP
ABSTRACT
 MATERIALS AND METHODS
 RESULTS
 DISCUSSION
 REFERENCES
 
1. Coltart T, Byrne D, Bates S. Meconium aspiration syndrome: A 6-year retrospective study. Br J Obstet Gynaecol 1989;96:411–4.[Medline]

2. Wiswell T, Tuggle J, Turner B. Meconium aspiration syndrome: Have we made a difference? Pediatrics 1990; 85:715–21.[Abstract/Free Full Text]

3. Katz V, Bowes W Jr. Meconium aspiration syndrome: Reflections on a murky subject. Am J Obstet Gynecol 1992;166:171–83.[Medline]

4. Hernandez C, Little B, Dax J, Gilstrap L, Rosenfeld C. Prediction of the severity of meconium aspiration syndrome. Am J Obstet Gynecol 1993;169:61–70.[Medline]

5. Yoder B. Meconium-stained amniotic fluid and respiratory complications: Impact of selective tracheal suction. Obstet Gynecol 1994;83:77–84.[Abstract/Free Full Text]

6. Wiswell T, Gannon C, Jacob J, Goldsmith L, Szyld E, Weiss K, et al. Delivery room management of the apparently vigorous meconium-stained neonate: Results of the multicenter, international collaborative trial. Pediatrics 2000;105:1–7.[Abstract/Free Full Text]

7. Hintz S, Suttner D, Sheehan A, Rhine W, Van Meurs K. Decreased use of neonatal extracorporeal membrane oxygenation (ECMO): How new treatment modalities have affected ECMO utilization. Pediatrics 2000;106:1339–43.[Abstract/Free Full Text]

8. Clark R, Yoder B, Sell M. Prospective randomized trial of HFO and CV in neonatal respiratory disease. J Pediatr 1994;124:447–54.[Medline]

9. Findlay R, Taeusch H, Walther F. Surfactant replacement therapy for meconium aspiration syndrome. Pediatrics 1996;97:48–52.[Abstract/Free Full Text]

10. Moller J, Kohl M, Reiss I, Diederich W, Nitsche E, Gopel W, et al. Saline lavage with substitution of bovine surfactant in term neonates with meconium aspiration syndrome transferred for extracorporeal membrane oxygenation: A pilot study. Crit Care 1999;3:19–22.[Medline]

11. Clark R, Kueser T, Walker M, and the CINOR Group. Low-dose nitric oxide therapy for persistent pulmonary hypertension of the newborn. N Engl J Med 2000;342: 469–74.[Abstract/Free Full Text]

12. Macri C, Schrimmer D, Leung A, Greenspoon J, Paul R. Prophylactic amnioinfusion improves outcome of pregnancy complicated by thick meconium and oligohydramnios. Am J Obstet Gynecol 1992;167:117–21.[Medline]

13. Cialone P, Sherer D, Ryan R, Sinkin R, Abramowicz J. Amnioinfusion during labor complicated by particulate meconium-stained amniotic fluid decreases neonatal morbidity. Am J Obstet Gynecol 1994;170:842–9.[Medline]

14. Hofmayer G. Amnioinfusion for meconium-stained liquor. Curr Opin Obstet Gynecol 2000;12:129–32.[Medline]

15. Pierce R, Gaudier F, Sanchez-Ramos L. Intrapartum amnioinfusion for meconium-stained amniotic fluid: Meta-analysis of prospective clinical trials. Obstet Gynecol 2000; 95:1051–6.[Abstract/Free Full Text]

16. Starks G. Correlation of meconium-stained amniotic fluid, early intrapartum fetal pH, and Apgar scores as predictors of perinatal outcome. Obstet Gynecol 1980;56:604–9.[Abstract/Free Full Text]

17. Krebs H, Petres R, Dunn L, Jordan H, Segreti A. Intrapartum fetal heart rate monitoring. III. Association of meconium with abnormal fetal heart rate patterns. Am J Obstet Gynecol 1980;137:936–42.[Medline]

18. Mitchell J, Schulman H, Fleischer A, Farmakides G, Nadeau D. Meconium aspiration and fetal acidosis. Obstet Gynecol 1985;65:352–5.[Abstract/Free Full Text]

19. Dijxhoorn M, Visser G, Fidler V, Touwen B, Huisjes H. Apgar score, meconium and acidemia at birth in relation to neonatal neurological morbidity in term infants. Br J Obstet Gynaecol 1986;93:217–22.[Medline]

20. Dooley S, Pesavanto D, Depp R, Socol M, Tamura R, Wiringa K. Meconium below the vocal cords at delivery: Correlation with intrapartum events. Am J Obstet Gynecol 1985;153:767–70.[Medline]

21. Steer P, Eigbe F, Lissauer T, Beard R. Interrelationships among abnormal cardiotocograms in labor, meconium staining of the amniotic fluid, arterial cord blood pH, and Apgar scores. Obstet Gynecol 1989;74:715–21.[Abstract/Free Full Text]

22. Rossi E, Philipson E, Williams T, Kalhan S. Meconium aspiration syndrome: Intrapartum neonatal attributes. Am J Obstet Gynecol 1989;161:1106–10.[Medline]

23. Paz Y, Solt I, Zimmer E. Variables associated with meconium aspiration syndrome in labors with thick meconium. Eur J Obstet Gynecol Reprod Biol 2001;94:27–30.[Medline]

24. Meydanli M, Dilbaz B, Caliskan E, Dilbaz S, Haberal A. Risk factors for meconium aspiration syndrome in infants born through thick meconium. Int J Gynecol Obstet 2001; 72:9–15.[Medline]

25. Usta I, Mercer B, Sibai B. Risk factors for meconium aspiration syndrome. Obstet Gynecol 1995;86:230–4.[Abstract]

26. American College of Obstetricians and Gynecologists. Recommended approaches for antenatal Group B Streptococcal prophylaxis. ACOG Newsletter 1993;37:2.

27. Hosmer D, Hosmer T, le Cessie S, Lemeshow S. A comparison of goodness-of-fit tests for the logistic regression model. Stat Med 1997;16:965–80.[Medline]

28. Usta I, Mercer B, Aswad N, Sibai B. The impact of a policy of amnioinfusion for meconium-stained amniotic fluid. Obstet Gynecol 1995;85:237–41.[Abstract]

29. Erikson N, Hostetter M, Parisi V. Prophylactic amnioinfusion in pregnancies complicated by thick meconium. Am J Obstet Gynecol 1994;171:1026–30.[Medline]

30. Spong C, Ogundipe O, Ross M. Prophylactic amnioinfusion for meconium-stained amniotic fluid. Am J Obstet Gynecol 1994;171:931–5.[Medline]

31. Crowley P. Interventions for preventing or improving outcome of delivery at or beyond term. Cochrane Database Syst Rev 2000;2:CD000170.




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