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.     

The need for delivery room intubation of thin meconium in the low-risk newborn: a clinical trial.

The delivery room management of meconium-stained amniotic fluid remains controversial. We attempted to determine if intubation of the low-risk newborn with thin meconium affects the incidence of respiratory symptoms. Exclusion criterion included moderate or thick meconium, fetal distress, neonatal depression, or prematurity. Eligible infants were randomized to either an intubation (group I) or to a nonintubation group (group II). The outcome was the presence of respiratory symptoms. Patients were studied from May 1994 to June 1997. There were 8967 births during this period: 7.9% (708/8967) were delivered through meconium. Thin meconium was noted in 50.3% (356/708) of all births. 24/356 infants with thin meconium were excluded for medical criterion. One hundred sixty-three infants were medically eligible but could not be randomized due to lack of consent, late arrival of the team, or obstetrician request. These were placed into intubation (group I B) and nonintubation (group II B) groups. Seventy-seven infants were randomized into group I and 92 infants into group II. From the intubation groups I and I B, one required supplemental oxygen and was weaned to room air in 7 hr. From the nonintubation groups II and II B, two infants required oxygen, weaning to room air in 11 and 46 hr. Comparing birth weight, gestational age, sex, mode of delivery and 5-min Apgar, there were no significant differences. However, the intubation groups had significantly lower 1-min Apgar scores. There was no airway morbidity reported in the intubation groups. In the infant with thin meconium and an otherwise low-risk pregnancy, we were unable to demonstrate a difference in respiratory symptoms with intubation and intratracheal suctioning.     

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.     

Possible Causes Linking Asphyxia, Thick Meconium and Respiratory Distress

The cause of fetal distress and neonatal respiratory distress (RD) in association with meconium-stained liquor is not always clear. To clarify this, a prospective study was undertaken in a tertiary referral maternity hospital for 1 year. In all infants born after meconium-stained liquor who developed RD, evidence was sought for 1) fetal distress (from the cardiotocograph (CTG), the cord blood pH, the Apgar score and the asphyxial complications in the neonate) 2) causes of fetal distress (including maternal risk factors, fetal infection and fetal malnutrition) 3) causes of respiratory distress (including meconium aspiration syndrome (MAS), persistent pulmonary hypertension of the newborn (PPHN) and infection). Of 4,026 livebirths, 717 (17.8%) had meconium-stained liquor and 44 term and 5 preterm infants developed RD. In the 44 term infants, there was frequent evidence of fetal distress possibly caused by previously unrecognized factors such as fetal malnutrition with reduced neonatal skinfold thickness in 35% triceps and 41% subscapular measurements, and histological chorioamnionitis (CA) in 74%. The cause for respiratory distress was identified in only 48% of infants, and included clinical evidence of PPHN (41%), MAS (16%) and infection (2%). However in preterm infants, 80% had definite or suspected infection. The findings indicate that fetal distress is common in infants who develop respiratory distress after meconium-stained liquor. A role for histological CA and reduced nutrition in the fetus, as factors contributing to the vulnerability of the term infant to intrapartum fetal distress, is suggested.     

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 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.     

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.     

Risk factors for meconium aspiration syndrome in infants born through thick meconium.

OBJECTIVE: To determine risk factors for meconium aspiration syndrome (MAS). METHOD: A cohort study was conducted of 70 consecutive singleton pregnancies complicated with thick meconium-stained amniotic fluid delivered at > or = 37 weeks' gestation. Cases were randomized either for elective abdominal delivery or spontaneous vaginal delivery after 20 min of external fetal heart rate (FHR) monitoring. Risk estimation analysis for MAS was performed calculating relative risks (RR) and odds ratios (OR). RESULTS: The presence of meconium below the vocal cords (RR=7.3, 95% CI=2.6-20.3), non-reassuring FHR tracings (RR=3.0, 95% CI=1.2-7.5), Apgar score < or = 6 at 5 min (RR=3.8, 95% CI=1.7-8.4) and an umbilical cord plasma erythropoietin (UCPer) level > 50 mlU/ml (RR=5.0, 95% CI=2.1-12.0) were found to be significant risk factors for MAS. The presence of meconium below the vocal cords (OR=33.4, 95% CI=3.6-303.7) and non-reassuring FHR tracings (OR=12.2, 95% CI=1.3-111.7) remained as significant risk factors at the end of the multivariate analysis. CONCLUSION: Non-reassuring FHR tracings and the presence of meconium below vocal cords are associated with an increased risk for MAS in infants born through thick meconium.     

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.     

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.     

Meconium aspiration and fetal acidosis

Meconium in labor is associated with increased perinatal morbidity and mortality. To identify the infants at risk, 53 women with moderate-to-thick meconium were followed in labor after obtaining baseline fetal scalp blood pH levels. Although 28 of the newborns (53%) exhibited an arterial cord pH of less than 7.25 at delivery, there were no significant predictive variables found in the electronic fetal monitoring score, Apgar score, or mode of delivery. Nine of the infants with a pH value of less than 7.25 had meconium below the vocal cords at delivery, but none in the infants with pH levels greater than or equal to 7.25. The P50 value for cumulative acidosis is 55 minutes, indicating a more rapid deterioration than an average-for-gestational-age fetus without meconium. Therefore, the presence of thick meconium implies that fetal stress must be avoided during labor, and early intervention is warranted when there is deviation from normal labor progress or fetal heart rate pattern.     

Significance of assay of nucleated RBCs in umbilical cord blood in neonates with meconium-stained amniotic fluid

Background: Approximately 8–15% of all infants are born with evidence of meconium-stained amniotic fluid (MSAF). MSAF is a potentially serious sign of fetal compromise and may indicate fetal hypoxia

Objectives and aim of the work: The present study was designed to evaluate the relationship between meconium stained amniotic fluid and fetal nucleated red blood cell counts. As well, we aim to evaluate the relationship between the presence of meconium in amniotic fluid and Apgar scores in neonates.

Subjects and methods: A prospectively case-controlled study was performed on 40 women with clear amniotic fluid as control and 40 women with meconium-stained amniotic fluid as the study group. At delivery, 2?ml of umbilical cord blood was collected and analyzed for nucleated red blood cell (NRBC).

Results: The mean NRBC counts in meconium-stained amniotic fluid was significantly higher than the control group (18.35?±?7.7 and 9.6?±?4.96), respectively (p?p?Conclusion: Our results support previous studies which indicate the presence of meconium can be associated with chronic fetal hypoxia as demonstrated by elevated fetal NRBC levels.     

Variables associated with meconium aspiration syndrome in labors with thick meconium

OBJECTIVE: To examine the possible maternal and fetal variables associated with meconium aspiration syndrome in labors with thick meconium. STUDY DESIGN: The fetal heart rate tracings, cord pH, Apgar scores and maternal risk factors were evaluated in singleton pregnancies with vertex presentation and thick meconium in labor. The study included 33 consecutive fetuses which developed a moderate or severe meconium aspiration syndrome and 104 consecutive fetuses which had a favorable outcome. RESULTS: Significant differences between fetuses with meconium aspiration syndrome and healthy fetuses were found in the following parameters: baseline FHR (154+/-17 vs. 136+/-10, P<0.0001), small accelerations/30 min (1.47+/-1.52 vs. 3.04+/-1.2, P<0.0001), large accelerations/30 min (1.46+/-1.96 vs. 3.5+/-2.31, P<0.0003), decelerations/30 min (4.9+/-3.9 vs. 2.4+/-2.1, P<0.0034), number of fetuses with reduced beat-to-beat variability (9/33 vs. 0/104, P<0.0001), cord pH (7.21+/-0.09 vs. 7.33+/-0.08, P<0.0013) and Apgar scores at 1 min (5+/-2 vs. 8+/-1, P<0.0001) and Apgar scores at 5 min (8+/-2 vs. 9.7+/-0.6, P<0.0001). Maternal risk factors were found in two of 33 sick infants and in 13 of 104 healthy infants. CONCLUSION: Thick meconium by itself is not associated with adverse fetal outcome. However, the incidence of meconium aspiration syndrome increases in cases of a non-reassuring FHR.     

Meconium aspiration syndrome: intrapartum and neonatal attributes

To identify the fetus and newborn at risk for meconium aspiration syndrome the perinatal characteristics of 238 infants delivered through meconium-stained amniotic fluid were prospectively examined. All infants with meconium-stained amniotic fluid were routinely suctioned with a DeLee apparatus before tracheal intubation and suctioning. The type and presence of meconium in the trachea, neonatal breathing before intubation, and Apgar scores were recorded in the delivery room. Intrapartum fetal monitoring data were collected for 80% (190/238) of the mothers and umbilical artery pH for 74% (177/238) of the newborns. Despite suctioning with a DeLee apparatus and endotracheal suctioning, meconium was present in the trachea in 87/238 (37%) and meconium aspiration syndrome developed in 22 (9.2%). A total of 73% of newborns who had meconium aspiration syndrome were delivered through thick meconium. Thick meconium, the presence of fetal tachycardia, and absence of intrapartum fetal cardiac accelerations identified the fetus at high risk for meconium aspiration syndrome. The presence of these monitoring findings and thick meconium should alert obstetricians to the possibility of a fetus that requires intervention. Low umbilical artery pH, Apgar scores less than 5, and meconium in the trachea further characterized the newborn at high risk for meconium aspiration syndrome. The combination of these findings may best identify the infant delivered through meconium-stained amniotic fluid who requires close observation for meconium aspiration syndrome.     

Meconium stained amniotic fluid in very low risk pregnancies at term gestation

Objective: To determine the prevalence and clinical significance of meconium stained amniotic fluid (MSAF) in a low risk population at term gestation and to investigate whether MSAF is a predictor for intrapartum and neonatal morbidity. Methods: A very low risk population including 37 085 consecutive deliveries at term composed the study population. A cross-sectional study was conducted and two groups of patients were identified according to the presence (n=6164) or absence (n=30 921) of meconium in the amniotic fluid at delivery and the outcomes of the two groups compared. Results: The prevalence of MSAF was 16.6%. The incidence of cesarean section (5.6% vs 2.3% P<0.01), instrumental deliveries (3.2% vs 1.8% P<0.01), fetal distress (6.5% vs. 2.1% P<0.01), clinical chorioamnionitis (0.2% vs. 0.1% P<0.01), post-partum infection (0.5% vs. 0.2% P<0.01), 1-minute Apgar score <3 (1.9% vs. 1.1% P<0.01), small for gestational age (7.4% vs. 6.4% P<0.01). was significantly higher in the MSAF compared with the clear amniotic fluid group. Intrapartum and neonatal mortality in this low risk population was significantly higher in the MSAF group ( ) compared with women with clear AF ( ). Conclusions: MSAF in a low risk population at term gestation is a predictor for adverse perinatal outcome and peripartum complications.     

Risk of meconium-stained amniotic fluid in different ethnic groups.

BACKGROUND: Recent studies indicate that the risk of meconium-stained amniotic fluid (MSAF) varies in different ethnic groups. This study prospectively examined the ethnic variation of MSAF and meconium aspiration syndrome, adjusting for gravidity, gestational age (GA), and birth weight. METHOD: The study population consisted of 6901 consecutive live births and included 31 different nationalities, seven main ethnic (race) groups, gravidity between 1 and 19, GA between 22 and 44 weeks, and birth weights between 350 and 6292 gm. RESULTS: The overall incidence of MSAF was 19% (13% thin, 6% thick). The prevalence of meconium aspiration syndrome was 5% in thick MSAF and none in thin MSAF. The incidence of MSAF differs significantly by ethnicity (14% to 30%), gravidity (17% to 23%), GA (6% to 46%), and birth weight (11% to 28%). Multivariate logistic regression analysis using the same variable showed that being black African, post-term, with a gravidity of > or = 7 and a birth weight of > or = 4000 gm significantly increased the chance for MSAF but not meconium aspiration syndrome. After controlling for these clinical variables, the black African infants had a higher percentage of MSAF at all GAs compared with the other ethnic groups. CONCLUSION: This study showed that the risk of MSAF varied by ethnicity and increased with higher gravidity, a GA of > 42 weeks, and a birth weight of > or = 4000 gm The higher incidence of MSAF without an increase in meconium aspiration syndrome in some ethnic groups may indicate advancing maturity of the gastrointestinal system in black ethnic groups compared with others of the same GA.     

Meconium-stained amniotic fluid—Perinatal outcome and obstetrical management in a low-risk suburban population

Objective

To determine whether amniotic fluid (MSAF) affects obstetrical interventions and immediate perinatal outcome in a low-risk suburban population.

Study design

A retrospective cohort study examined 11,226 deliveries at Tübingen University Hospital (1998–2003). Thousand one hundred and twenty-three women (10%) had MSAF during labor. A control group of matched pairs was created, assigning to each patient the next woman that gave birth without MSAF. Exclusion criteria were: gestational age less than 37 + 0 weeks, primary Cesarean (C-)section, multiple gestation, severe maternal disease, preeclampsia and fetal malformations.

Results

Only small differences were noted between the meconium and non-meconium groups with regard to arterial pH and Apgar scores: mean arterial-pH was 7.26 (±0.7) for both. Five minutes Apgar scores <6 occurred in 0.9% versus 0.4%. Obstetrical interventions were more common in the meconium group: C-section rates were 17.4% versus 9.6%, vaginal operative delivery rates 13.9% versus 6.2% and scalp pH rates 9.5% versus 3.7%, respectively.

Conclusions

In a low-risk suburban population the effect of MSAF on the newborn during the immediate postpartum period was small. However, obstetrical management was significantly effected by the presence of MSAF, possibly reflecting a combination of more difficult labor and a lower threshold for obstetric intervention.     

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.     

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.     

Incidence of and factors associated with meconium staining of the amniotic fluid in a Nigerian University Teaching Hospital.

This study was conducted to determine the incidence of meconium staining of the amniotic fluid (MSAF) and its associated factors in a Nigerian teaching hospital. Perinatal data on 80 consecutive live, singleton infants of booked mothers born through meconium-stained liquor from March - June 2003 were analysed and compared with babies born through clear liquor. The incidence of MSAF was 20.4% for 393 deliveries. The rate increased with gestational age: no case was found below 37 weeks (p = 0.001). Primiparity, prolonged rupture of fetal membranes and obstructed labour were more often associated with MSAF (p = 0.005, p = 0.0013 and p = 0.0000002, respectively) as were tachycardia or bradycardia and low Apgar scores (p = 0.0000001 and p = 0.046, respectively). It is concluded that meconium-staining is common. It is related to gestational maturity and stressful peripartum conditions and associated with adverse symptomatology in the fetus and newborn.