Obstetric and perinatal outcome of pregnancies with term labour and meconium-stained amniotic fluid

The purpose of this study was to evaluate the meconium staining of amniotic fluid (AF) in term of fetal distress, meconium aspiration syndrome, and perinatal morbidity and mortality. In a prospective study at Princess Badeea Teaching Hospital from April to November 1999, women with a singleton cephalic pregnancy of completed 37–42 weeks and with no pre-defined risk factor were recruited into the study. Study patients comprised 390 (10%) patients with meconium and 400 patients as controls but with clear amniotic fluid. Virtually meconium staining of the amniotic fluid was significantly associated with poor neonatal outcome in all outcomes measures assessed. Perinatal mortality increased from 2 per 1000 births with clear AF to 10 per 1000 with meconium (P<0.001). Other adverse outcomes also increased; e. g. , severe fetal acidemia, Apgar score ≤3 at 1 min and 5 min, and meconium aspiration syndrome. Delivery by cesarean section also increased with meconium from 7–14% (P<0.001). We concluded that meconium in the amniotic fluids associated with an obstetric hazard and significantly increase risks of adverse neonatal outcomes. Women with thin meconium in the presence of normal fetal heart rate can be safely managed at the clinical level. Mod-thick meconium alone should alert the obstetrician to a high risk fetal condition. Continuos fetal heart rate monitoring during labour and reassurance of fetal well-being by acid-base assessment were most significant factors in the reduction of meconium aspiration syndrome. Received: 15 November 1999 / Accepted: 12 April 2000     

Fetal outcome in obstetric cholestasis

Summary. Obstetric cholestasis has been associated with a high incidence of stillbirth and perinatal complications. Between 1975 and 1984, 83 pregnancies were complicated by cholestasis. Meconium staining occurred in 45%, spontaneous preterm labour in 44%, and intrapartum fetal distress in 22%. Of 86 infants two were stillborn and one died soon after birth. Perinatal mortality fell from 107 in a previous series from this hospital (1965–1974) to 35/1000 in this series. Cardiotocography, estimations of oestriol, liver function tests and ultrasonic assessment of amniotic fluid volume failed to predict fetal compromise, whereas amniocentesis revealed meconium in 8 of 26 pregnancies. Early intervention was indicated in 49 pregnancies, 12 because of fetal compromise. This study suggests that intensive fetal surveillance, including amniocentesis for meconium, and induction of labour at term or with a mature lecithin/sphyngomyelin ratio, may reduce the stillbirth rate in this 'high-risk' condition.     

Fetal outcome in obstetric cholestasis

Obstetric cholestasis has been associated with a high incidence of stillbirth and perinatal complications. Between 1975 and 1984, 83 pregnancies were complicated by cholestasis. Meconium staining occurred in 45%, spontaneous preterm labour in 44%, and intrapartum fetal distress in 22%. Of 86 infants two were stillborn and one died soon after birth. Perinatal mortality fell from 107 in a previous series from this hospital (1965-1974) to 35/1000 in this series. Cardiotocography, estimations of oestriol, liver function tests and ultrasonic assessment of amniotic fluid volume failed to predict fetal compromise, whereas amniocentesis revealed meconium in 8 of 26 pregnancies. Early intervention was indicated in 49 pregnancies, 12 because of fetal compromise. This study suggests that intensive fetal surveillance, including amniocentesis for meconium, and induction of labour at term or with a mature lecithin/sphyngomyelin ratio, may reduce the stillbirth rate in this 'high-risk' condition.     

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.     

Obstetric outcome in post-term pregnancies: time for reappraisal in clinical management

BACKGROUND: The objective of this study was to determine the outcome of pregnancy in post-term cases compared with term cases in a well defined population receiving modern obstetric care. METHODS: We utilized the population-based birth registry data of the Kuopio University Hospital (1990-2000) to investigate pregnancy outcome in 1,678 post-term singleton pregnancies. The general obstetric population (n=22,712) was used as a reference group in logistic regression analysis. RESULTS: The overall frequency of post-term pregnancies was 6.9% and the incidence of post-term pregnancies was found to be increased in obese, primiparous, and smoking women, whereas in women with chronic diseases and obstetric risks deliveries were induced earlier. The risks of macrosomia, maternal complications, and operative deliveries were increased in post-term pregnancies. Post-term infants experienced meconium passage (21.2% versus 12.8%) (p<0.01) and intrapartum asphyxia (3.4% versus 2.1%) (p<0.01) significantly more often than the controls. However, the stillbirth rate was low, probably due to careful monitoring of these pregnancies. CONCLUSIONS: Although high-risk pregnancies were not allowed to come post-term, postmaturity per se is a moderate risk state compromising fetal well-being with regard to meconium passage and acid-base status at birth. We conclude that simple antenatal monitoring beyond 42 weeks reduces perinatal mortality but is inefficient in reducing meconium-stained liquor seen with increasing gestation.     

Significance of meconium during labor.

Continuous fetal heart rate (FHR) monitoring and routine fetal scalp blood sampling was utilized in the evaluations of 366 fetuses during labor. One hundred and six patients had meconium in the amniotic fluid at some time during labor. A total of 26,110 uterine contractions were monitored during these 366 labors. The incidence of FHR patterns as a percentage of uterine contractions was calculated for the meconium and nonmeconium groups. Although there was a 3 1/2-fold increase in the incidence of low five-minute Apgar scores (less than 7) in the meconium group, signs of fetal distress were, with rare esception, not significantly different from those in the nonmeconium group. The presence of meconium in the amniotic fluid without signs of fetal asphyxia (late decelerations and acidosis) is not a sign of fetal distress and need not be an indication for active intervention. The combination of fetal asphyxia and meconium staining of the amniotic fluid, however, does enhance the potential for meconium aspiration and a poor neonatal outcome. Universal fetal heart rate monitoring and appropriate fetal acid-base evaluation is recommended for following patients with meconium in the amniotic fluid during labor.     

Perinatal outcomes with intrahepatic cholestasis of pregnancy in twin pregnancies

Objective: To describe perinatal outcomes of twin pregnancies complicated by intrahepatic cholestasis of pregnancy (ICP).

Methods: We conducted a retrospective cohort study of women delivered at a large tertiary obstetric center in Shanghai, China from January 2006 to May 2014. Delivery data were abstracted from medical records of all twin gestations delivered at the hospital.

Results: A total of 129/1922(6.7%) twin and 1190/92?273 singleton (1.3%) pregnancies were complicated by ICP. An increased risk of stillbirth among twin pregnancies was observed (3.9% and 0.8% in the ICP and non-ICP groups, respectively; aOR 5.75, 95% CI 2.00–16.6). Stillbirths with ICP and twins occurred between 33 and 35 weeks gestation compared to 36–38 weeks gestation among singletons. ICP in twins was also associated with an increased risk of preterm birth (<37 weeks) with an aOR of 4.17 (95% CI 2.47–7.04) and an aOR of 1.89 (95% CI 1.26–2.85) for delivery <35 weeks. Twin pregnancies complicated by ICP also had increased meconium staining of amniotic fluid and lower birth weight.

Conclusions: Twin pregnancies with ICP have significantly increased risks of adverse perinatal outcomes including stillbirth and preterm birth. Stillbirth occurs at an earlier gestational age in twin gestation compared to singletons, suggesting that earlier scheduled delivery should be considered in these women.     

Cesarean delivery for fetal distress: rate and risk factors

The objective of this article was to review the recent English language literature on cesarean delivery for fetal distress to determine its incidence, diagnostic tests, and the contributing factors to this obstetric complications. A PubMed search (1990-2000) with items of "cesarean, fetal distress," "cesarean, non-reassuring fetal heart rate," "cesarean, neonatal acidosis," and "cesarean, umbilical arterial pH," was undertaken. Reports, letters to the editor, focus on anomalous fetuses, and papers not specifically focused on this topic were excluded. Of the 392 articles that the search yielded, 169 met the inclusion criteria. Based on 37 reports with more than 1,000 patients each, the overall risk of prompt cesarean delivery for fetal concern was 3.1% (43,340 of 13,989,74). The risk exceeded 20% in patients with moderate/severe asthma, severe hypothyroidism, severe preeclampsia, and postterm or fetal growth restricted fetuses with abnormal Doppler studies. Use of likelihood ratios suggests that Doppler of the umbilical artery is a superior diagnostic test to amniotic fluid index in identifying parturients at risk for cesarean for non-reassuring fetal heart rate tracing. Although several risk factors increase the need for cesarean delivery for fetal distress, in general, most are unpreventable. TARGET AUDIENCE: Obstetricians & Gynecologists, Family Physicians. LEARNING OBJECTIVES: After completion of this article, the reader will be able to estimate the incidence of cesarean delivery for non-reassuring fetal heart rate tracing, outline potential diagnostic tests that are useful for the detection of fetal distress, and summarize medical and obstetric conditions that place patients at risk for cesarean delivery for fetal distress.     

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.     

Monitoring of labour and delivery in the presence of meconium stained amniotic fluid by pulse oximetry

OBJECTIVES: Evidence of meconium-stained amniotic fluid during labor suggests implementation of close monitoring of fetal well-being. DESIGN: Our purpose was to compare fetal oxygen saturation between cases with normal and meconium stained amniotic fluid. MATERIALS AND METHODS: Fetal oxygen saturation was continuously recorded with use of Nellcor N-400 fetal pulse oximeter in 30 control cases of term labour of normal, and 30 cases of meconium stained amniotic fluid. Distribution of fetal oxygen saturation values during 5 periods of labour was analyzed and compared between the examined groups, and presented in forms of Tables, together with neonatal umbilical artery pH values, Apgar score, birth weight and percentage of caesarian sections performed. RESULTS: No significant differences in fetal oxygen saturation, neonatal umbilical artery pH, birth weight and caesarian sections rate were observed between analyzed groups. Newborns 1-th minute Apgar score (mean value) and base excess was lower in meconium group compared to control group. CONCLUSIONS: Our data demonstrate, that fetal oxygen saturation trends to decrease during labour in fetuses in both groups.     

Predicting concordance of biochemical lung maturity in the preterm twin gestation

Objective: To determine the occurrence of maternal and fetal complications in low-risk pregnancies beyond 39 weeks and to re-evaluate the acceptable cut-off (42 weeks) for induction of labor. Study design: A total of 36 160 low-risk pregnancies with reliable dating of gestational age (last menstrual period and early ultrasound examination) were evaluated retrospectively for fetal and maternal complications, including non-progressive labor, cervical tear, retained placenta, postpartum hemorrhage, vacuum delivery, Cesarean section, macrosomia, meconium-stained amniotic fluid, non-reassuring fetal heart rate monitoring and ante-, intra- and postpartum death. Pregnancy outcomes at different gestational ages were compared using univariate and multivariate analysis and receiver operator curves. Results: The rates of non-progressive labor stage I and II, retained placenta, vacuum delivery, Cesarean section, macrosomia, meconium-stained amniotic fluid and non-reassuring fetal heart rate monitoring were found to be significantly higher with increasing gestational age in the univariate analysis. These parameters were evaluated using multivariate analysis and the following were found to be significantly higher: non-progressive labor stage I and II, macrosomia, meconium-stained amniotic fluid and Cesarean section. Statistical analysis (receiver operator curves) showed that the most significant rise in the risk for non-progressive labor occurred after 42 completed weeks of gestation, and after 41 completed weeks for macrosomia, meconium-stained amniotic fluid and Cesarean section. Conclusions: The rates of non-progressive labor stage I and II, meconium-stained amniotic fluid, macrosomia and Cesarean section were significantly higher with increasing gestational age. In order to decrease the rate of macrosomia, meconium-stained amniotic fluid and Cesarean section, we suggest that induction of labor should be considered before 42 weeks.     

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.     

Meconium-stained amniotic fluid across gestation and neonatal acid-base status

OBJECTIVE: To estimate whether the acid-base status of neonates born to women with meconium-stained amniotic fluid varies across gestation. METHODS: We carried out a retrospective cohort study of all pregnancies that were complicated by meconium-stained amniotic fluid in 2004. Cases were identified from a perinatal pathology database that contained data on all pregnancies complicated by meconium-stained amniotic fluid. Data abstracted from the charts included gestational age at delivery, umbilical arterial pH, birth weight, and the presence or absence of labor. Cases were stratified according to gestational age at delivery. The distribution of meconium-stained amniotic fluid across gestation was computed. The mean umbilical arterial pH values (with 95% confidence intervals) across gestation were assessed by analysis of variance. RESULTS: The mean umbilical arterial pH in women with meconium-stained amniotic fluid did not differ across gestation. The overall incidence of meconium-stained amniotic fluid was 12.0% (766 of 6,403 deliveries). The rates of meconium-stained amniotic fluid increased from 1.2% at 32 weeks to 100% at 42 weeks. CONCLUSION: The rising incidence of meconium-stained amniotic fluid with gestational age is consistent with the hypothesis that fetal maturation is a major etiologic factor in meconium passage. Also, the lack of variation of mean umbilical arterial pH across gestation suggests that fetal acidemia is not increased when meconium passage occurs earlier in pregnancy rather than at later gestational ages.     

Obstetric Outcome During an Era of Active Management for Obstetrics Cholestasis

Objective

To study the incidence, maternal, and perinatal outcomes in intrahepatic cholestasis of pregnancy with active management.

Materials and Methods

This observational study included 48 cases diagnosed as intrahepatic cholestasis of pregnancy. Medical treatment and active management (fetal surveillance and termination of pregnancy at 37–38 weeks) were offered to all. Maternal and perinatal outcomes are studied.

Results

Incidence of ICP was 2.4 %. More than 86 % of patients presented with generalized pruritus mostly after 30 weeks. Incidences of Intrapartum abnormal cardiotocography (12.5 %) and thick meconium (8.33 %) were high. Cesarean section rate was high (41.66 %). Most common indications were CDMR, fetal distress, and non-progress of labor. Incidence of preterm labor, IUGR, Apgar score (<7), and neonatal admission rate were not high. There was one stillbirth at 36 weeks of gestation. Serum transaminase levels tended to be higher in patients with poor perinatal outcomes, such as stillbirth, fetal distress, and meconium-stained amniotic fluid.

Conclusion

Serum transaminase levels tended to be higher in patients with poor perinatal outcome. Perinatal outcome is good with active management, at the cost of higher LSCS rate. Further randomized controlled trial of early versus spontaneous delivery may be justified.

     

Meconium passed in labor: how reassuring is clear amniotic fluid?

OBJECTIVE: Clear amniotic fluid is frequently considered a reassuring sign during labor. Our aim was to examine the incidence of meconium that can only have been passed intrapartum and to determine its neonatal associations and whether its absence is a useful sign. METHODS: This was a prospective cohort study of 8394 "low risk" laboring women at term with clear amniotic fluid at early amniotomy. RESULTS: Meconium was passed in 5.2% of labors but was not detected until delivery of the fetal head in 51.5% of these. It was associated with moderate-severe acidosis (odds ratio [OR] 4.40; 95% confidence interval [CI] 3.21, 6.03), low Apgar score at 5 minutes (OR 6.49; 95% CI 2.73, 15.44), and neonatal seizures (OR 4.33; 95% CI 3.17, 5.93). However, the sensitivity for these outcomes of the intrapartum passage of meconium and, particularly, its detection before delivery was very poor. CONCLUSION: Although correlated with adverse neonatal outcomes, most affected infants had clear amniotic fluid throughout labor. The presence of clear amniotic fluid is an unreliable sign of fetal well-being.     

Prognostic value of change in amniotic fluid color during labor

OBJECTIVE: Evidence of meconium-stained amniotic fluid (AF) during labor suggests implementation of close monitoring of fetal well-being. We have investigated whether the presence of meconium in the AF on admission for labor is as important a predictor of neonatal outcome as a change in AF color during labor. METHODS: AF characteristics on admission for labor at term (37-42 weeks) and their changes during labor were recorded in all singleton pregnancies during an 8-year period (1992-1999). Excluded were stillbirths on admission, congenital anomalies, and elective cesarean sections. The presence of meconium and its consistency (light or thick) were documented on admission by inspection with transcervical amnioscopy in women with intact membranes or in the vaginal pool in those with ruptured membranes. Changes in AF color or consistency during labor were recorded and correlated with the obstetric and neonatal outcome. Statistical analysis utilized chi(2) for trend, with p < 0.05 considered significant. RESULTS: 19,090 women were admitted in labor at term during the study period and fulfilled the study inclusion criteria and had amniotic fluid evaluation available. The appearance of meconium or worsening in thickness of meconium during labor was associated with higher rates of Apgar scores <7 at 5 min (clear AF on admission and at delivery 0.6%; light or thick meconium on admission and no change at delivery 0.8%; clear AF on admission and light or thick meconium at delivery 3.2%, and light meconium on admission and thick meconium at delivery 2.5%; p < 0.001) and umbilical artery pH <7.10 (the respective rates in the four groups were 1.7, 1.8, 3.6, and 3.8%; p < 0.001). CONCLUSION: The appearance or thickening of meconium during labor has a greater predictive ability for depressed neonates than the presence of meconium on admission.     

羊膜腔输液治疗在产时应用的临床分析

目的 :分析羊膜腔输液 (amnioinfusion,AI)治疗产时羊水过少、胎膜早破和胎粪性羊水的临床意义。方法 :选择产程中发生胎心异常合并羊水过少、胎膜早破和羊水胎粪污染的孕产妇 1 0 1例 ,随机分为治疗组 51例 ,对照组 50例。治疗组在胎心监护下行羊膜腔输液或羊水置换 ;对照组给予吸氧 ,改变体位 ,静滴 5% Na HCO3等治疗。结果 :治疗组经羊膜腔输液 50 0～ 1 0 0 0 ml,胎心可变减速 (variable deceleration,VD)和长时减速 (period long deceleration,PL D)消失或明显改善 44例 ,有效率占 86 .3% ,明显高于对照组 (2 2 % ) ,两组比较差异有显著性 (P<0 .0 1 )。治疗组 1 9例胎粪性羊水行羊水置换 ,有 1 7例羊水转为清亮或 度混浊。治疗组产程时间比对照组缩短 ,治疗组和对照组剖宫产率分别为 1 3.7%和 34.0 % ,新生儿窒息率分别为 3.9%和 42 .0 % ;对照组胎粪吸入性肺炎 9例 ,新生儿死亡 3例 ,治疗组仅一例发生胎粪吸入性肺炎 ,无新生儿死亡。产褥病率两组比较 ,差异无显著性 (P>0 .0 5)。结论 :羊膜腔输液是治疗产时羊水过少、胎膜早破、胎粪性羊水的有效方法     

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.     

Unconjugated serum oestriol levels in mother and baby with meconium staining of the amniotic fluid

To examine the effect on oestrogen metabolism of the stimulus which causes the passage of meconium, we measured maternal venous and cord artery and vein serum unconjugated oestriol levels in 46 patients with meconium staining of the amniotic fluid and 19 controls. Mean cord vein oestriol levels were significantly lower than in controls in the presence of meconium stained amniotic fluid and no fetal acidosis (cord artery buffer base of 36.2 meq/l or more) (P less than 0.02). The same tendency was seen with acidotic infants (P less than 0.05). There is thus evidence of a change in oestrogen metabolism associated with meconium staining of the amniotic fluid.     

Pyruvate kinase in human amniotic fluid--a new indicator of fetal maturity in late pregnancy

During the second and third trimesters increasing activities of the glycolytic enzyme pyruvate kinase are to be found in human amniotic fluid. At term (37 to 42 weeks), a very steep rise in amniotic fluid pyruvate kinase can be noticed, which may serve as an additional prenatal indicator of fetal maturity. The presumable main sources of the enzyme in amniotic fluid are the epithelium cells of the skin, the respiratory tract and the amnion. In meconium stained amniotic fluid no pyruvate kinase activity is detectable. Addition of meconium to amniotic fluid samples with previously present pyruvate kinase activity leads to a disappearance of the enzyme activity.