Risk factors for meconium aspiration in meconium stained amniotic fluid.

Meconium aspiration syndrome (MAS) is a life-threatening respiratory disease in infants born through meconium stained amniotic fluid (MSAF). The purpose of this study was to determine risk factors for MAS in the newborns of mothers who had meconium stained amniotic fluid in labour. A retrospective study of all full-term pregnancies with MSAF from May 2003 to October 2004 was designed at a teaching hospital. Development of MAS was the primary outcome. Maternal details, mode of delivery and neonatal details (Apgar score, reassuring or non-reassuring fetal heart rate tracing and birth weight) were evaluated. During the study period, there were 2,603 deliveries of whom 302 (11.6%) had MSAF. MAS developed in 64 of these infants (21.1%). Compared with healthy neonates with MSAF, those with MAS had higher rate of non-reassuring fetal heart rate (FHR) tracing, thick meconium and Apgar score < or =5 at 5 min. The neonatal birth weight was lower in the MAS group, maternal age, parity, gestational age and mode of delivery were not significantly different in the two group. We found the severity of meconium, low Apgar score at 5 min and non-reassuring FHR tracing was associated with MAS in MSAF pregnancies.     

Meconium staining and meconium aspiration syndrome. Is there seasonal variation?

OBJECTIVE: To determine whether the incidence of pregnancies complicated by meconium-stained amniotic fluid (MSAF) or meconium aspiration syndrome (MAS) differs with seasonal changes. METHODS: An established perinatal database was used to identify all term (> or = 37 weeks) singleton gestations resulting in a live birth from January 1, 1997 to December 31, 1999. Patients were divided into groups based on the season of delivery: winter (December-February), spring (March-May), summer (June-August), and fall (September-November). Rates of MSAF (%MSAF/total deliveries) and MAS (%MAS/total deliveries) were calculated and compared among seasons. Local climatic data (average monthly temperature and monthly precipitation) were obtained from the National Weather Service. Multiple logistic regression analysis was performed to control for the effects of confounding variables and odds ratio (OR) with 95% confidence intervals (CI) were calculated. p < 0.05 was considered significant. RESULTS: Over the 3-year study period there were a total of 14,888 deliveries meeting the criteria. MSAF occurred in 3,206 (21.5%) deliveries and MAS developed in 92 (0.6% of total, 2.9% of MSAF). There were no differences in the rate of MSAF (p = 0.2) or MAS (p = 0.6) between seasons. By logistic regression neither season, temperature, nor precipitation were associated with MSAF or MAS. CONCLUSIONS: Our findings suggest that over the period examined there were no significant seasonal variations in the incidence of MSAF or MAS.     

Significance of meconium-stained amniotic fluid in the preterm population.

OBJECTIVE: Numerous studies have assessed the significance of meconium-stained amniotic fluid (MSAF) at term. However, to date, there has been very little documentation on the incidence and significance of meconium in the preterm population. Our objective was to define the incidence of MSAF in patients delivering prematurely (<37 weeks) and examine its association with underlying fetal acidosis, Apgars and admission to the neonatal intensive care unit (NICU). METHOD: All patients delivering at a single tertiary care center between June 1994 and September 1997 were reviewed for the presence of meconium and gestational age <37 weeks at delivery. Maternal demographics and birth outcomes including cord gases, Apgar scores and admission to the NICU were collected. Exclusion criteria included multiple gestations, breech presentations, fetal anomalies and patients not in labor. RESULTS: Out of a total of 9570 patients there were 506 (5.3%) preterm births meeting the inclusion criteria, of whom 24 (4.8%) had MSAF noted either during labor or at delivery. Comparing the preterm group with and without meconium, there were no differences in maternal age, gravidity, rate of Cesarean section, or gestational age at delivery. Cord pH (7.27 meconium vs. 7.29 no meconium) and base excess (-5.1 meconium vs. -4.0 no meconium) were similar in both groups. There were no clinically significant differences in mean Apgar scores at 1 and 5 minutes. However, an increased number of NICU admissions were noted in the group with meconium (75% vs. 53%, p=0.04). CONCLUSION: The incidence of meconium staining of the amniotic fluid in labor in the preterm population is less than 5% and by itself is not a significant marker of fetal acidosis.     

Racial disparity in meconium-stained amniotic fluid and meconium aspiration syndrome in the United States, 1989-2000

OBJECTIVE: To estimate the prevalence of meconium-stained amniotic fluid and meconium aspiration syndrome, as well as the differences in case fatality from meconium aspiration syndrome, between non-Hispanic black and non-Hispanic white infants. METHODS: We studied non-Hispanic black and non-Hispanic white live births with weights greater than 2.5 kg and gestational ages greater than 35 weeks, using the linked US birth and infant death cohorts for three periods: 1989-1991, 1995-1997, and 1998-2000. We used logistic regression to estimate the risks of meconium-stained amniotic fluid and meconium aspiration syndrome and to estimate the case fatality of meconium aspiration syndrome by maternal race, birth weight, period, and pregnancy complications. RESULTS: Risk of meconium-stained amniotic fluid was 80% higher in non-Hispanic blacks when compared with non-Hispanic whites (birth weight-adjusted odds ratio [OR], 1.81, 95% confidence interval [CI] 1.80, 1.82). The prevalence of pregnancy complications did not explain this racial disparity. Risk of meconium aspiration syndrome in non-Hispanic blacks was 67% higher when compared with non-Hispanic whites (birth weight-adjusted OR 1.67, 95% CI 1.64, 1.70). The case fatality rate of meconium aspiration syndrome was similar between non-Hispanic blacks and non-Hispanic whites in the three periods, with rates of 15.5, 15.2, and 11.2 per 1000 in non-Hispanic blacks and 13.5, 11.2, and 10.1 per 1000 in non-Hispanic whites in 1989-1991, 1995-1997, and 1998-2000, respectively. CONCLUSION: Our results suggest that when compared with non-Hispanic whites, non-Hispanic blacks are at significantly greater risk for meconium-stained amniotic fluid and meconium aspiration syndrome but not for meconium aspiration syndrome case fatality.     

Incidence of meconium aspiration syndrome in term meconium-stained babies managed at birth with selective tracheal intubation.

The delivery room management of infants born through meconium stained amniotic fluid (MSAF) remains controversial. The aim of this prospective study was to evaluate maternal and neonatal characteristics of MSAF infants and the incidence of meconium aspiration syndrome (MAS) in routine delivery room management which reserved selective intubation for depressed/asphyxiated babies. Between October 1993 and September 1997, a consecutive sample of 3745 full-term infants was analyzed. Of these, 361 were MSAF infants. No significant difference in maternal age, parity, gestational age, sex, low 1 and 5 minute Apgar scores, metabolic acidemia, or need for endotracheal intubation was found between MSAF and non-MSAF infants. Only one of the MSAF infants (0.28%), who needed intubation, developed MAS. Identification of postterm pregnancy and prenatal asphyxia is the best prevention of MAS.     

Meconium-stained amniotic fluid

Passage of meconium usually occurs within 48 hours after birth. However, some fetuses may pass meconium in-utero leading to meconium staining of amniotic fluid (MSAF). The vast majority of fetuses pass meconium in-utero due to the physiological maturation of the fetal gut with advancing gestation leading to normal defaecation in utero. However, clinicians need to exclude ‘non-physiological’ causes of MSAF, especially an ongoing hypoxia or chorioamnionitis, to improve perinatal outcomes. Meconium aspiration syndrome (MAS) is a potentially serious fetal condition with increased risk of severe morbidity and mortality. The use of the cardiotocograph (CTG), timely recognition of ongoing hypoxia or infection, consideration of the overall clinical picture and avoidance of injudicious use of oxytocin may help avoid poor perinatal outcomes and resultant medico-legal consequences.     

Impact of race and ethnicity on the outcome of preterm infants below 32 weeks gestation.

OBJECTIVES: To determine the impact of race/ethnicity on mortality and morbidity such as intraventricular hemorrhage (IVH), periventricular leukomalacia (PVL), bronchopulmonary dysplasia (BPD) and bacteriologically confirmed sepsis, assisted ventilation, surfactant administration, intrauterine growth retardation (IUGR), and patent ductus arteriosus (PDA) among very prematurely delivered infants. STUDY DESIGN: Retrospective study of a cohort of 1006 preterm neonates with gestational age ranging from 22 to 32 weeks discharged from the Neonatal Intensive Care Unit (NICU) between 1998 and 2001. Subgroup analysis according to gestational age (GA) (22 to 24, 25 to 28, and 29 to 32 weeks) and plurality (singleton and multiple) was performed using the chi(2) test and an analysis of variance. RESULTS: Of the 1006 infants, 54.3% were white, 21.7% black, 13.7% Hispanic, and 10.3% were classified as Other. Multiple births among white infants were approximately twice that in (42.4%) black infants (22.1%), and was also significantly higher than in the Hispanic (28.3%) and other race/ethnic groups (25.2%). Overall, a higher proportion of black infants were born with a GA 相似文献   

Meconium aspiration syndrome in term neonates with normal acid-base status at delivery: Is it different?

OBJECTIVE: Our aim was to compare the clinical characteristics of meconium aspiration syndrome in cases with pH > or =7.20 and in those with pH <7.20. STUDY DESIGN: Medical records of diagnostic codes from the International Classification of Diseases, Ninth Revision, were used to identify neonates with severe meconium aspiration syndrome who had been delivered at our institution from 1994 through 1998. Severe meconium aspiration syndrome was defined as a mechanical ventilator requirement of >48 hours. Clinical data including neonatal outcomes of cases of meconium aspiration syndrome associated with umbilical pH > or =7.20 at delivery were compared with data on outcomes of cases with pH <7.20. RESULTS: During this 4-year study period, 4985 singleton term neonates were delivered through meconium-stained amniotic fluid. Forty-eight cases met all study criteria, and pH values at delivery were as follows: pH > or =7.20, n = 29, and pH <7.20, n = 19. There were no differences between groups in the incidence of clinical chorioamnionitis, in the presence of meconium below the vocal cords, or in birth weight. Neonates with meconium aspiration syndrome and umbilical pH > or =7.20 at delivery developed seizures as often as those with pH <7.20 (20.1% vs 21.1%; P = 1.0). CONCLUSION: Normal acid-base status at delivery is present in many cases of severe meconium aspiration syndrome, which suggests that either a preexisting injury or a nonhypoxic mechanism is often involved.     

Delivery room risk factors for meconium aspiration syndrome

The objective of this study is to identify risk factors for meconium aspiration syndrome (MAS) in newborns born through meconium-stained amniotic fluid (MSAF). From May 27, 1994 to June 9, 1997 maternal and neonatal data were prospectively collected on all infants born through MSAF. Development of MAS was the primary outcome. Using bivariate and logistic regression analysis we identified risk factors for MAS. There were 8,967 births during this period: 7.9% (708 of 8,967) were delivered through MSAF. Respiratory symptoms developed in 6.8% (48 of 708) of births. Of these, 50% (24 of 48) were excluded due to the diagnosis of transient tachypnea of the newborn (17), respiratory distress syndrome (4), group B streptococcus pneumonia (1), congenital cytomegalic inclusion disease (1), and supraventricular tachycardia (1). Of the 24 infants with respiratory symptoms consistent with MAS, 45.8% (11 of 24) required ventilatory support, one required extracorporeal-membrane oxygenation. Bivariate analysis identified six risk factors ( p <0.05): Apgar <7 at 1 minute, Apgar <7 at 5 minutes, thick meconium, fetal distress, suction of infant's stomach by delivery room team at <5 minutes of age, and need for resuscitation. Tracheal meconium was very prevalent in our population at 74% of all intubated infants, and was not significantly associated with MAS. Logistic regression analysis identified four independent risk factors. Looking at multiple prediction models, an infant with fetal distress, Apgar <7 at 1 and 5 minutes and thick meconium has a 79.8% probability of developing respiratory symptoms. If these risk factors are not present, there is a 0.8% risk. In our cohort, this group had 16.7% positive predictive value (4 of 24) and 99.6% negative predictive value (657 of 660). In meconium deliveries, infants with thick meconium, fetal distress, and Apgar scores <7 at 1 and 5 minutes are at high risk for development of respiratory symptoms. Infants delivered in the absence of all of these risk factors are at low risk for development of MAS.     

Ethnic disparity in the success of vaginal birth after cesarean delivery.

OBJECTIVE: To estimate whether maternal race/ethnicity is independently associated with successful vaginal birth after cesarean delivery (VBAC). STUDY DESIGN: A retrospective cohort study from January 1, 1997 to July 30, 2002 of women with singleton pregnancies and a previous cesarean delivery. The odds ratio (OR) for successful VBAC as a function of ethnicity was corrected for age >35 years, parity, weight gain, diabetes mellitus, hospital site, prenatal care provider, gestational age, induction, labor augmentation, epidural analgesia, and birth weight >4000 g. RESULTS: Among 54 146 births, 8030 (14.8%) occurred in women with previous cesarean deliveries. The trials of labor rates were similar among Caucasian (46.6%), Hispanic (45.4%), and African American (46.0%) women. However, there was a significant difference among ethnic groups for VBAC success rates (79.3% vs. 79.3% vs. 70.0%, respectively). When compared to Caucasian women, the adjusted OR for VBAC success was 0.37 (95% confidence interval (CI) 0.27-0.50) for African American women and 0.63 (95% CI 0.51-0.79) for Hispanic women. CONCLUSION: African American and Hispanic women are significantly less likely than Caucasian women to achieve successful VBAC.     

Nucleated red blood cells in meconium aspiration syndrome

OBJECTIVE: To evaluate whether the absolute nucleated red blood cell (RBC) count is higher in infants who had meconium aspiration with respiratory symptoms compared with infants with asymptomatic meconium aspiration and controls. METHODS: We compared the absolute nucleated RBC counts during the first 12 hours of life in three groups of term, vaginally delivered infants, including those who had meconium aspiration with respiratory symptoms (n = 11), asymptomatic meconium aspiration (n = 45), and control healthy infants (n = 32). We excluded infants of women with diabetes in pregnancy; hypertension; alcohol, tobacco, or drug abuse; and those with hemolysis, blood loss, or chromosomal anomalies. RESULTS: There were no significant differences among groups in gestational age; gravidity; parity; maternal analgesia; lymphocyte, platelet, and granulocyte counts; and hematocrit. The median nucleated RBC count was significantly higher in the meconium aspiration group with respiratory symptoms (0.007 x 10(9)/L) than the asymptomatic meconium aspiration group (0.004 x 10(9)/L) or controls (0.003 x 10(9)/L). CONCLUSION: At birth, infants with meconium aspiration syndrome had higher absolute nucleated RBC counts compared with infants with asymptomatic meconium aspiration and normal infants.     

Should fetal scalp blood sampling be performed in the case of meconium-stained amniotic fluid?

Objective: To investigate the effect of using fetal scalp blood sampling on the risk of neonatal respiratory distress syndrome (NRDS) with meconium-stained amniotic fluid (MSAF).

Methods: Prospective data collection with regard to MSAF during labor for low-risk term cephalic singleton live birth from 2012 to 2014. Maternal, obstetric and neonatal data were compared according to the occurrence of respiratory distress syndrome (RDS group) or not (no RDS group).

Results: Of 515 newborns born through MSAF, 46 experienced RDS and from them 10 experienced meconium aspiration syndrome. No difference was observed according to maternal characteristic, abnormal fetal heart rate tracing pattern irrespective of its category and cesarean rate. Apgar at one?minute was lower in the group RDS (7.6 versus 8.5, p?<?0.05). The mean umbilical artery pH values did not differ between the two groups. Significant difference between newborns with and without RDS in terms of fetal scalp lactate sampling during the labor (71.1% versus 55.1%, p?<?0.05), and neonatal care unit (NCU) admissions (22.8% versus 10.8%, p?<?0.05). Secondary rather than primary meconium was associated with RDS when performing fetal scalp blood assessment (p?<?0.05). A significant correlation between RDS, fetal scalp blood assessment and MSAF diagnosed during the first stage of labor (after spontaneous rupture of membranes or at amniotomy) was found.

Conclusion: In case of MSAF, fetal scalp blood sampling did not reduce the risk of RDS.     

Meconium stained fluid: approach to the mother and the baby

Meconium aspiration syndrome (MAS) is a common problem that most pediatricians will encounter in the delivery room and normal newborn nursery. Approximately 13% of all live births are complicated by meconium stained amniotic fluid (MSAF). MAS is defined as respiratory distress in an infant born through MSAF whose symptoms cannot be otherwise explained. Optimal care for an infant born through MSAF involves cooperation between the obstetrician and pediatrician, each with separate but imperative roles.     

Meconium-stained amniotic fluid and its association with obstetric infections

Meconium-stained amniotic fluid (MSAF) complicates the intrapartum course of 1.5% to 18% of pregnancies. In addition to predisposing to the meconium aspiration syndrome, MSAF is also an established risk factor for neonatal sepsis and for intrapartum and postpartum maternal infection. Meconium enhances the growth of bacteria in amniotic fluid by serving as a growth factor, inhibits the bacteriostatic properties of amniotic fluid, and antagonizes host defense systems such as phagocytosis, thus explaining the association between MSAF and intrauterine infection. Other evidence suggests that the presence of intraamniotic infection may actually cause passage of meconium in utero by inducing fetal enteritis and gastrointestinal hypermotility. Prophylactic intravenous ampicillin-sulbactam has been shown to be effective in significantly decreasing the rate of chorioamnionitis in patients with MSAF. Additional investigation is necessary to determine the optimal prophylactic antibiotic(s) and method of drug administration in patients with MSAF.     

Meconium-stained amniotic fluid and neonatal morbidity in near-term and term deliveries with acute histologic chorioamnionitis and/or funisitis.

OBJECTIVE: To determine the incidence of meconium-stained amniotic fluid (MSAF) and neonatal morbidity in near-term and term deliveries with histologic acute chorioamnionitis and/or funisitis compared to those with normal placental histology. STUDY DESIGN: In a retrospective case-control design, we compared the incidence of MSAF and neonatal outcome in 45 cases of acute histologic chorioamnionitis and/or funisitis with 89 cases of normal placental histology. We reviewed the obstetric and neonatal records for perinatal complications and neonatal morbidity. RESULTS: Mean birthweights (3372+/-473 vs 3287+/-518 g) were similar in infants born to mothers with histologic chorioamnionitis and/or funisitis compared to infants born to mothers with normal placental histology. The incidence of MSAF was significantly higher in the group with acute chorioamnionitis/funisitis (p<0.05). Similarly, the incidence of admissions to newborn intensive care unit, respiratory distress, meconium aspiration syndrome, and presumed sepsis was also significantly higher (p<0.05) in this group. CONCLUSION: The incidence of MSAF and neonatal morbidity is higher in the presence of acute inflammation of placental membranes. The presence of meconium in the amniotic fluid should alert the physician to the potential for infection and increased neonatal morbidity.     

Meconium-stained amniotic fluid in term pregnancies-a clinical view.

The objective of this study was to explore details of the clinical relationship between meconium-stained amniotic fluid (MSAF) in labour, abnormal fetal heart pattern and meconium aspiration (MA). This was a prospective study carried out in Princess Badeea Teaching hospital during a 6-month period from March to September 1997. During the study period 344 (8.5%) of the deliveries had MSAF (344 women). Continuous fetal heart monitoring was routinely used and 36 women with MSAF (10.5%) needed to be delivered by caesarean section because of fetal distress (diagnosed by abnormal fetal heart pattern) in early labour, compared with 0.95% in those with clear amniotic fluid (CAF), (P <0.00001). Many infants in the MSAF group had a low Apgar score and required ventilation at birth. Nineteen infants (5.5%) developed MA, three of whom (15.8%) died. We conclude that there is an association between MSAF, abnormal fetal heart pattern in labour and a low Apgar score and that it should be considered a high risk situation. MA a problem that occurs with particulate meconium was significantly related to abnormal fetal heart pattern and longer length of labour.     

Prophylactic amnioinfusion improves outcome of pregnancy complicated by thick meconium and oligohydramnios.

OBJECTIVE: The null hypothesis is that the use of intrapartum amnioinfusion in labors complicated by the presence of thick meconium and oligohydramnios will not decrease the incidence of fetal distress, cesarean delivery, meconium aspiration, or meconium aspiration syndrome. STUDY DESIGN: One hundred seventy term and postterm patients with thick meconium and oligohydramnios were randomly chosen to receive amnioinfusion or standard obstetric care without amnioinfusion. The frequency of fetal distress, cesarean section, meconium aspiration, and meconium aspiration syndrome were subject to chi 2 analysis, Student's t test, or Fisher's exact test. RESULTS: The rate of fetal distress was significantly reduced in the amnioinfusion group compared with controls (three of 85 vs 19 of 85, relative risk 0.15, 95% confidence interval 0.06 to 0.42). The rate of cesarean section for fetal distress was significantly reduced in the amnioinfusion group (two of 85 vs 17 of 85, relative risk 0.118, confidence interval 0.03 to 0.49). The rates of meconium aspiration (four of 85 vs 33 of 85, relative risk 0.12, confidence interval 0.0449 to 0.327) and meconium aspiration syndrome (0 of 85 vs five of 85, relative risk 0.09, confidence interval 0.009 to 0.872) were significantly reduced by amnioinfusion. CONCLUSIONS: Amnioinfusion improves the outcome in pregnancies complicated by thick meconium and oligohydramnios.     

Have the year 2000 neonatal resuscitation program guidelines changed the delivery room management or outcome of meconium-stained infants?

OBJECTIVE:To study the impact of neonatal resuscitation program (NRP) guidelines on delivery room (DR) management of infants born through meconium-stained amniotic fluid (MSAF).STUDY DESIGN:A retrospective study of all term (>or=37 weeks) infants born through MSAF was performed. Patients were divided into two periods: pre year 2000 NRP and post year 2000 NRP. Meconium consistency, APGAR scores and intubation (INT) for suctioning and respiratory outcome were recorded. Groups were analyzed using chi (2) tests and stepwise logistic regression.RESULTS:The incidence of MSAF remained constant in period 1 (13.6%) and period 2 (13.1%) while the proportion of infants intubated fell from 67 to 41% (p<0.001). The incidence of meconium aspiration and nonspecific respiratory distress did not differ between groups.CONCLUSIONS:Since the implementation of year 2000 NRP guidelines, the rate of DR INT for tracheal suctioning has fallen significantly without a change in overall respiratory complications. Results of this study support the efficacy of year 2000 NRP recommendations.     

Intrapartum and postdelivery management of infants born to mothers with meconium-stained amniotic fluid: evidence-based recommendations

The article reviews and critically evaluates the available evidence to determine whether the current recommendations for the management of infants born through meconium stained amniotic fluid (MSAF) should be maintained. Authors provide evidence-based recommendations regarding the benefits of amnioinfusion prior to delivery, oral suctioning of the newborn prior to delivery of the shoulder, and the practice of routine endotracheal suctioning of the newborn born through MSAF in preventing meconium aspiration syndrome (MAS). Authors also discuss the gaps in knowledge in all the above interventions to prevent MAS.     

Intrapartum amnioinfusion for meconium-stained amniotic fluid: a systematic review of randomised controlled trials

BACKGROUND: Amnioinfusion (AI) is thought to dilute meconium when present in the amniotic fluid and so reduces the risk of meconium aspiration. OBJECTIVES: To evaluate if AI reduces meconium aspiration syndrome (MAS) and other indicators of morbidity in babies born to women with meconium-stained amniotic fluid (MSAF). SEARCH STRATEGY: PubMed, Medline, EMBASE, and the Cochrane Controlled Trials Register from January 1980 to May 30, 2005, using the keywords 'amnioinfusion' and 'meconium'. SELECTION CRITERIA: Randomised trials comparing AI with no AI for women in labour with MSAF. Trial quality was evaluated using pre-established criteria. DATA COLLECTION AND ANALYSIS: The following morbidity indicators were assessed: MAS, 5-minute Apgar score < 7, arterial cord pH < 7.2, and caesarean section. Studies were stratified according to the level of peripartum surveillance (standard versus limited). Typical relative risks (RRs) with their 95% confidence intervals were calculated for each outcome using a random effects model. MAIN RESULTS: In clinical settings with standard peripartum surveillance, we found no evidence that AI reduced the risk of MAS (RR 0.59, 95% CI 0.28-1.25), 5-minute Apgar score < 7 (RR 0.90, 95% CI 0.58-1.41), or caesarean delivery (RR 0.89, 95% CI 0.73-1.10). In clinical settings with limited peripartum surveillance, AI appeared to reduce the risk of MAS (RR 0.25, 95% CI 0.13-0.47). CONCLUSION: In clinical settings with standard peripartum surveillance, the evidence does not support the use of AI for MSAF. In settings with limited peripartum surveillance, where complications of MSAF are common, AI appears to reduce the risk of MAS. However, this finding requires confirmation by further studies.