Volume 29, Issue 6

Aim: To discuss maternal and fetal metabolic events during labor and the possible role of glucose administration. Results: The oxidative pathway covers the largest part of the energy demand of labor, although in the second stage or, in polysystolic labor, the non-oxidative pathway becomes important as well. Glucose is the main maternal energy source, but the rise in ketobodies, even during normal labor, suggests a relative shortage. In the first stage of labor, a combination of a respiratory alkalosis, and to a lesser extent, a metabolic acidosis, result in a rise in the maternal pH. In the second stage of labor, the maternal pH decreases due to an increasing metabolic acidosis. Glucose is also the main fetal energetic fuel. In fetal hypoxia, lactate is produced, which in most cases is transferred to the maternal circulation. High maternal lactate concentrations, however, may interfere with this process. Furthermore, fetal hyperglycemia may lead to an increased fetal lactate production. Conclusions: Maternal hyperglycemia, may lead to an increase in maternal and fetal lactate production resulting in metabolic acidosis. Unlike high dosage intravenous glucose administration, it is not likely that oral intake of carbohydrates leads to maternal and fetal hyperglycemia and subsequently to metabolic acidosis, but studies are rare.

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.

The chances and quality of survival depend on gestational age at birth. Why has PTD not decreased during the last decade, in spite of all the known risk factors? Perinatal data bases tend to include biomedical risk factors and are assembled and analysed retrospectively. These data should form the basis for prediction, and risk factors such as stress, anxiety, inflammation (leading to elevated CRH with its role in PTD), short cervix etc, should be added when assessed prospectively. The goal is preconception and early prediction in pregnancy. Only with the implementation of efficient intervention will we lengthen pregnancies and lower the VPTD rate. More articles about the PTD and complications of preterm births should be published in the lay press. There is no room for pessimism: if everybody involved would do just a little in the right direction, the result would be enormous. Constant auditing of interventions is necessary. The most difficult to “cure” and most likely to relapse are stress, anxiety and social factors, and discrimination in obtaining basic health care. Long forgotten lessons of compassion with pregnant women have not yet been acknowledged as proven to change VPTD into PTD, but are available at no cost world wide.

Background: Infants of diabetic mothers (IDM) often have delayed lung development and are thus at an increased risk of Respiratory Distress Syndrome (RDS). Both hyperglycemia and/or hyperinsulinemia have been implicated in this delay but the precise mechanism has not been clarified. Another metabolite, sodium butyrate, which is increased in IDM has been shown to decrease surfactant production in vitro but its effects on the development of the fetal lung surfactant system in vivo have not been studied. Aim: To investigate the in vivo effects of high glucose and sodium butyrate treatment on maternal and fetal glucose and insulin levels and on fetal lung surfactant maturation using timed-pregnant New Zealand White rabbits. Methods: On the 24th day of gestation the doe was implanted s.c. with time release pellets containing either glucose (300 mg), sodium butyrate (200 mg) or matching placebo. On the 27th or 30th day maternal (ear vein) and fetal (cardiac puncture) blood samples were drawn for glucose and insulin determinations. Fetal surfactant pools (both intra- and extracellular) were quantitatively harvested using differential and density gradient centrifugation and their phospholipid profiles determined. Data were statistically compared with ANOVA and Duncan's Multiple Range Test. Results: Neither glucose nor sodium butyrate affected maternal plasma glucose or insulin. Both metabolites significantly increased fetal plasma insulin, decreased fetal plasma glucose but did not delay any of the parameters of surfactant maturation examined. Conclusions: Fetal hyperinsulinemia, whether attained by prolonged exposure to elevated glucose or sodium butyrate in vivo does not appear to be the causative agent for delayed lung maturity which frequently occurs in infants of diabetic mothers.

In this paper we demonstrate the usefulness of an eigenvector based spatial filtering method for signal processing of multi-channel fetal magnetocardiogram (fMCG) and fetal magnetoencephalogram (fMEG) recordings. This method of filtering can separate signal and interference by exploiting the considerable spatial information contained in multi-channel recordings. Typically, fMCGs and fMEGs suffer from large cardiac interference and low signal-to-noise ratio. To isolate the signal from the interference, we identify their respective subspaces using one portion of the record dominated by the signal and another dominated by the interference. Each subspace is approximately rank two since the sources of the signal and interference can be modeled as current dipoles. The spatial filter consists of a linear transformation that preserves the signal subspace and annihilates the interference subspace. It is easier to implement than a matched filter, preserves the morphology and topography of the fetal signal, and effectively removes maternal cardiac interference, even when the maternal and fetal complexes overlap strongly in time or when small maternal movements or maternal arrhythmias alter the temporal character of the interference.

Aims: To investigate localization and concentration of adhesion molecules in the human lower uterine segment during preterm parturition. Methods: In a prospective study biopsy specimens from the lower uterine segment of 43 patients undergoing cesarean section at 24 + 0 to 36 + 4 weeks' gestation were immunostained for intercellular adhesion molecule-1, endothelial leukocyte adhesion molecule-1, vascular cell adhesion molecule-1, and platelet endothelial cell adhesion molecule-1, and the concentrations measured by enzyme immunoassay. The results were analyzed in relation to the degree of cervical dilatation (< 2 cm, 2 – < 4 cm, ≥ 4 cm) and duration of labor (≤ 6 h, > 6–12 h; > 12 h). Results: Intercellular adhesion molecule-1 and platelet endothelial cell adhesion molecule-1 were strongly expressed by capillary endothelium, endothelial leukocyte adhesion molecule-1 and vascular cell adhesion molecule-1 to only a minor degree. Intercellular adhesion molecule-1 concentration was greater at ≥ 4 cm dilatation than at 2– < 4 cm and after > 12 h labor than after ≤ 6 h. Endothelial leukocyte adhesion molecule-1 concentration was greater after >12 h than after ≤ 6 h. Conclusions: Premature labor is associated with up-regulation of adhesion molecules in the lower uterine segment.

Objective: The hypothesis of this prospective study is that intrapartum vibroacoustic stimulation (VAS) is an effective predictor of fetal acidosis during labor. Various clinical conditions, such as term versus preterm gestation, first stage versus second stage of labor, and fetal heart rate (FHR) variable decelerations versus late decelerations will be tested. Methods: During the study period, 113 patients were studied prospectively in either active phase of first stage (n = 53) or during the second stage of labor (n = 60). They were selected from cases exhibiting moderate to severe FHR variable decelerations or late decelerations. The fetuses of study subjects received a VAS for three seconds and FHR changes were recorded. Fetal scalp blood pH or umbilical arterial blood pH was obtained within 15 minutes of VAS. The relationship between FHR responses to VAS and fetal blood pH in term and preterm gestations, the relationship of two tests (VAS and fetal blood pH) to type of FHR decelerations, and the predictability of neonatal morbidity by two tests were analyzed. Where appropriate, Fisher's exact test (p < 0.05 was considered statistically different) and the odd ratio with 95% confidence intervals were used for statistical analyses. Results: Excellent association between acceleration response to VAS and pH ≥ 7.20, and between a negative response to VAS (no acceleration or decelerations) and pH < 7.20 were found in the first stage of labor, the second stage of labor, and the combination of both stages together (p = 0.0001, OR = 10.6 [3.3–34.0]). It was observed that negative VAS responses for predicting fetal acidosis (pH < 7.20) were comparable between term (≥ 37 weeks) and preterm (< 37 weeks, ≥ 34 weeks) fetuses. Since the preterm fetuses enrolled in the study were limited in number, it is difficult to draw adequate conclusions. The positive predictive value (PPV) of fetal acidosis was 67% in both groups of FHR variable decelerations and late decelerations, but the false negative rate of acceleration VAS response for predicting no acidosis was significantly higher in the group of late decelerations (29% vs 8 %, p = 0.034). Finally, both a negative VAS response and fetal acidosis (pH < 7.20) have equal predictability for neonatal morbidity. The PPV of NICU admission by a negative VAS response was two times higher than that of fetal acidosis (PPV = 61% vs 29%, p = 0.038). Conclusion: We found that intrapartum VAS was an effective predictor of fetal acidosis in cases of FHR variable decelerations, but its predictability for fetal acidosis in cases of FHR late decelerations was limited. Both VAS and fetal blood pH are good predictors of neonatal morbidity.

Aims: To evaluate whether maternal and fetal plasma adrenomedullin levels in pregnancies with small for gestational age (SGA) infants are different from those in pregnancies with appropriate for gestational age (AGA) infants. Methods: Maternal and fetal circulating adrenomedullin levels were compared between 62 pregnancies with AGA (43 delivered vaginally and 19 delivered by elective cesarean section) and 28 pregnancies with SGA (20 delivered vaginally and 8 delivered by elective cesarean section) at birth. Plasma adrenomedullin levels were measured from maternal and cord venous blood samples using a radioimmunoassay. Umbilical artery blood pH was also measured. Results: There were no significant differences for maternal total adrenomedullin levels, mature adrenomedullin levels, and its ratio among the groups. There were also no significant differences for fetal total adrenomedullin levels, mature adrenomedullin levels, and its ratio among the groups. In the AGA group delivered vaginally, fetal mature/total adrenomedullin ratio (mean ± standard error, 16.6 ± 0.7%) was significantly higher than the maternal ratio (13.8 ± 0.6%) (p < 0.05). In the SGA group delivered vaginally, fetal mature/total adrenomedullin ratio (18.5 ± 1.0%) was also significantly higher than the maternal ratio (14.5 ± 0.6%) (p < 0.05). There was no significant difference in umbilical artery blood pH among the groups. Conclusions. These results suggest that maternal and fetal plasma circulating adrenomedullin levels may play a role in maternal and fetal cardiovascular adaptation during delivery in pregnancies with both AGA and SGA infants.

Aims: To determine the concentrations of tumor necrosis factor α, interleukin-1β, interleukin-6, and interleukinin the lower uterine segment during preterm parturition. Methods: In 71 patients who delivered prematurely nonelective cesarean tissue specimens were obtained from the lower uterine segment. The patients were grouped in relation to the stage of cervical dilatation (< 2 cm, 2–< 4 cm, ≥ 4 cm), duration of labor (≤ 6h, > 6–12 h; > 12 h), and parity (1 versus > 1). Cytokine concentrations in protein extracts of the tissue samples were measured using enzyme-linked immunosorbent assays. Results: Median concentration of tumor necrosis factor α did not change, but that of interleukin-1β, interleukin-6, and interleukin-8 were significantly higher at 2–< 4 cm than at < 2 cm cervical dilatation (6.6, 67.7, and 125.8 versus 1.1, 17.6, and 22.2 pg/mg protein, respectively). The concentrations of interleukin-6 and interleukin-8 showed a further increase at ≥ 4 cm (297.2 and 468.6 pg/mg, respectively), but for interleukin 1β a decrease was observed (0.6 pg/mg). Cytokine concentrations were not related to duration of labor or parity. Conclusions: Local inflammationassociated changes that are mainly related to the stage of cervical dilatation and to only a minor degree to uterine activity may play a crucial role in preterm parturition.

Background: Dehydration, starvation, and enhanced blood coagulability may occur during labor. Methods: We studied 60 women who gave birth vaginally to a healthy singleton infant at term. Sampling of urine and blood specimens was performed on admission to the hospital with labor pains and just after birth. Paired samples were available from 50 women for urine analysis and 29 women for blood analysis. Total fluid intake (oral and intravenous) during labor was recorded. Changes in various parameters in the urine and blood in relation to the total fluid intake were analyzed. Results: Osmolality and creatinine concentration in the urine, red blood cell count, hemoglobin concentration, hematocrit value, thrombinantithrombin III complex, plasmin-α 2 -plasmin inhibitor complex and D dimer significantly increased during labor. Ketone bodies were absent in the urine in 84% (42/50) of women on admission to the hospital whereas these were present in 74% (37/50) of women just after delivery (p < 0.01). The degree of these changes appeared to be smaller with an increase in fluid intake. Conclusion: Concentrated urine, hemoconcentration, starvation, and activation of the thrombogenic and fibrinolytic system occur in parturient women. Sufficient fluid intake during labor may ameliorate these unfavorable changes.

Lightinduced fluorescence (LIF) of collagen was used to investigate in vivo changes in cervical collagen in guinea pigs during gestation and following sodium nitroprusside treatment. Natural fluorescence of collagen is due to collagen cross-linking molecules that connect single collagen fibers and therefore provide rigidity of the cervical stroma. LIF of cervical collagen was measured from the surface of the exocervix in anesthetized nonpregnant and timed pregnant guinea pigs at different times of gestation with an instrument designed in our lab (Collascope™). Measurements were also performed in guinea pigs at midgestation before and 8 hours after intracervical treat ment with sodium nitroprusside. Collagen fluorescence decreased significantly as pregnancy progressed, reached lowest values at delivery, and increased gradually postpartum. Treatment with sodium nitroprusside, but not with the vehicle, caused a significant decrease in LIF ( p = 0.007). We conclude, that LIF changes in the cervix reflect the gradual cervical softening (ripening) during pregnancy and the return to the rigid state of the cervix postpartum. Cervical softening during pregnancy, and after sodium nitroprusside treatment, is associated with a decrease in collagen cross-links. Measurements of LIF can be used to investigate cervical softening in vivo.