Fetal Rhythm Research Articles

The Fetus as a Cardiac Patient: Assessment and Therapy of Cardiovascular Pathology before Birth

The past few decades have seen major advances in evaluation and treatment of fetal cardiovascular diseases. Largely due to advances in imaging, recognition of structural pathology in the developing human heart can now be performed as early as the 12th week of pregnancy and can be seen to develop and progress through gestation. Because of the observation that serious structural congenital heart disease may progress from seemingly minor disease if untreated, several centers are now intervening before birth to address such abnormalities and attempt to prevent the further development of structural disease. Furthermore, detailed assessment of cardiac rhythm, function, and myocardial mechanics is now also possible as early as the first trimester. Transplacental treatment for fetal rhythm abnormalities has dramatically changed the outcomes for affected pregnancies in the past decade. More recently, several centers have begun to incorporate routine fetal cardiovascular assessment in the evaluation of diseases such as congenital cystic adenomatiod malformation of the lung, twin-twin transfusion syndrome, and congenital diaphragmatic hernia where structural disease may impose significant comorbidity postnatally, and hemodynamic derangements and functional pathology secondary to the primary process may impact the fetus in utero. Recognition of potentially treatable fetal cardiac disease may alter the prognosis for these patients in the perinatal period as in utero treatment to address the primary abnormality has been shown to improve the hemodynamic derangements observed. Finally, prenatal recognition of fetal cardiac disease in general may be changing the natural history and incidence of disease in the postnatal population. Regardless of training and background, any healthcare professional involved in the diagnosis and management of diseases of the fetus and newborn now needs to be cognizant of the potential contribution of prenatal cardiac assessment and treatment in the congenitally malformed or unwell fetus. In this special issue on the fetus as a cardiac patient, we have invited a few papers addressing issues unique to this patient group. The first paper of this special issue addresses ethical issues relating to fetal diagnosis of a major abnormality with special emphasis on cardiac malformations. Presented are discussions of the ethical concept of beneficence and the principle of patient autonomy in the context of counseling expectant mothers and the complex ethical situation which arises in the consideration of the fetus as a patient. The second paper presents a comprehensive review of cardiac findings in twin-to-twin transfusion syndrome (TTTS), a condition which is a severe complication of monochorionic twin pregnancy. TTTS is characterized clinically on ultrasound by polyhydramnios in the “recipient” twin and oligohydramnios in the “donor” with varying degrees of cardiac dysfunction in the recipient. The pathophysiology of the syndrome itself and of the development of cardiomyopathic changes remains incompletely understood. The review discusses what is known with respect to the cardiac findings at presentation, natural history, and response to treatment and discusses current approaches to a comprehensive cardiac evaluation of affected fetuses. The third paper describes a large series of fetuses presenting with findings consistent with cardiomyopathy or myocarditis and represents a large natural history study of these entities, underlining the particularly high perinatal loss rate with diagnosis of dilated cardiomyopathy or myocarditis, as opposed to many of the hypertrophic myopathies. The issue concludes with two thought-provoking review articles regarding the intrauterine environment and the complex interaction the developing fetal brain and circulatory system have with each other and the placental circulation. In the first of these, the authors present a discussion of intrauterine hypoxia, its various causes, and mechanisms whereby disease in the fetus may result. The final paper presents a comprehensive review of the current understanding of pathologic findings in the developing brain of the fetus and infant with congenital heart disease. Methods for detection, potential etiologies, and implications for neurodevelopmental outcome are discussed. Intriguing speculation regarding the possibility of altering the natural history of developmental brain abnormalities via in utero intervention will leave the reader eagerly anticipating future developments in the rapidly advancing field of fetal cardiovascular assessment and treatment. Anita J. Moon-Grady Shinjiro Hirose Greg Kesby Samuel Menahem Wayne Tworetzky

The underestimated potential of Doppler ultrasound to assess fetal arrhythmia: First report of a prenatal, transient, atypical atrioventricular block

Introduction Atrioventricular block (AVB) is a common issue in fetuses from mothers with autoimmune disease, but could also be encountered in healthy pregnancies. The assessment of heart rhythm in fetuses is challenging because transmaternal fetal electrocardiography (ECG) remains unreliable during part of gestation and involves signal averaging, limiting its clinical application. Fetal magnetocardiography, the magnetic analog of the fetal ECG, is at this time the most effective means of assessing fetal rhythms. However, as it requires a very expensive magnetically shielded facility, it is still primarily used for clinical research. The analysis of arrhythmias is therefore mostly based on evaluating the temporal relationship of circulatory markers of both atrial and ventricular contractions. Our technique, the superior vena cava (SVC)/ascending aorta (AA) approach, has been documented previously. Briefly, from a transverse crosssectional image at the level of the atrioventricular (AV) valves with the ultrasound beam directed at the left anterior or right posterior side of the fetus, a 4-chamber view is obtained with the heart in a vertical or slightly oblique position. From this position, 90° rotation shows a sagittal view of the fetus with the inferior vena cava, right atrium, and SVC connecting together (bull horn appearance). On this view, the AA and SVC appear closely related to each other. Slight cranial or caudal angulation allows the ultrasound beam to align with both vessels and to simultaneously record SVC/AA Doppler signals (Figure 1). AV correlation can then be assessed because the retrograde wave, caused by atrial contraction (A wave) in the SVC, and the onset of the aortic ejection wave (V wave, marker of ventricular contraction) are clearly identifiable (Figure 2). In our experience, the SVC/AA approach allows most fetal arrhythmias to be diagnosed. This is the technique of choice to detect and monitor AVB. Moreover, we have already described the appearance of typical type-I, seconddegree AVB (AVB-2) with Wenckebach phenomenon using this approach. We report the identification of an atypical, reversible, Wenckebach type AVB-2. To our knowledge, such an arrhythmia has never been described in prenatal life.

Antenatal Presentation of Congenital Long QT Syndrome: A Prenatal Diagnosis Not To Be Missed

We focus attention on the antenatal diagnosis of long QT syndrome (LQTS). Recent data show that a diagnosis of LQTS is possible at an early stage of life, namely, the fetal period, and that LQTS, now well established as capable of explaining some sudden infant death syndromes (SIDS), can explain some fetal loss [2, 8]. This new medical perspective implies strong preventative implications. Long QT syndrome is an heterogeneous inherited arrhythmia. To date, 10 responsible genes have been identified [7, 9]. The genetic prevalence is 1 to 2,000, but considering that most mutation carriers remain asymptomatic, clinical prevalence is less important [9]. Because LQTS is characterized by an abnormal prolongation of QT interval on electrocardiogram, it poses an increased risk of sudden death, usually due to ventricular fibrillation [9]. Echocardiography shows no heart structural abnormality [7, 9], and 25% of unexpected fetal loss cases remain unexplained after autopsy [6]. According to recent reports, LQTS can be diagnosed in utero. An M-mode echocardiogram or magnetocardiography, if available, can reveal sustained fetal bradycardia, decreased heart rate variability, 2:1 atrioventricular block, and ventricular arrhythmias [3–5, 10]. Fetal bradycardia is defined as a heart rate slower than 100 beats/min [4]. Recently, waveforms of torsade de pointes recorded on fetal magnetocardiogram at 28 weeks of gestation have been reported [6]. Parallel to these new fetal rhythm investigation methods, LQTS appears to be a silent killer among fetuses and newborns [8, 13]. An abnormal QT prolongation is associated with SIDS [11]. According to recent molecular screening studies, LQTS could be a strong contributor to SIDS, being responsible for 9.5% of them [1]. These findings suggest that abnormality in fetal rhythm compatible with LQTS (i.e., sustained fetal bradycardia, 2:1 atrioventricular block, or ventricular arrhythmias), even if there is no family history of sudden death, must require careful evaluation because of the risk for fetal loss, SIDS, or life-threatening events later in life. When LQTS is evoked, pregnancy should be managed in a medical center with cardiac facilities to allow preventive care such as beta-adrenergic blockers, adapted multidisciplinary follow-up assessment, identification of previously undiagnosed relatives, and early parental education with infant cardiopulmonary resuscitation and contraindicated medications. Beta-blocking therapy is known to be effective for children with LQTS [12], and some authors have reported prenatal treatment of fetal LQTS with beta-adrenergic blockers [3]. Further studies are needed to determine whether prenatal administration of this medication can be recommended.

Brain‐derived neurotrophic factor enhances fetal respiratory rhythm frequency in the mouse preBötzinger complex in vitro

Brain-derived neurotrophic factor (BDNF) is required during the prenatal period for normal development of the respiratory central command; however, the underlying mechanisms remain unknown. To approach this issue, the present study examined BDNF regulation of fetal respiratory rhythm generation in the preBötzinger complex (preBötC) of the mouse, using transverse brainstem slices obtained from prenatal day 16.5 animals. BDNF application (100 ng/mL, 15 min) increased the frequency of rhythmic population activity in the preBötC by 43%. This effect was not observed when preparations were exposed to nerve growth factor (100 ng/mL, 30 min) or pretreated with the tyrosine kinase inhibitor K252a (1 h, 200 nm), suggesting that BDNF regulation of preBötC activity requires activation of its cognate tyrosine receptor kinase, TrkB. Consistent with this finding, single-cell reverse transcription-polymerase chain reaction experiments showed that one third of the rhythmically active preBötC neurons analysed expressed TrkB mRNA. Moreover, 20% expressed BDNF mRNA, suggesting that the preBötC is both a target and a source of BDNF. At the network level, BDNF augmented activity of preBötC glutamatergic neurons and potentiated glutamatergic synaptic drives in respiratory neurons by 34%. At the cellular level, BDNF increased the activity frequency of endogenously bursting neurons by 53.3% but had no effect on basal membrane properties of respiratory follower neurons, including the Ih current. Our data indicate that BDNF signalling through TrkB can acutely modulate fetal respiratory rhythm in association with increased glutamatergic drive and bursting activity in the preBötC.

Differential effects of betamethasone on the fetus between morning and afternoon recordings

Background. Fetal heart rate (FHR) variation and fetal movements show a diurnal rhythm, a rise in the afternoon and evening compared to morning hours. A previous study showed that reductions in fetal parameters occurring two to three days after betamethasone administration are most likely caused by suppression of the normal rise during the day. Therefore monitoring during the morning could circumvent the suppressive effects of betamethasone.Objective. To study the effects of betamethasone on fetal diurnal rhythms, by comparing morning and afternoon recordings over five successive days.Methods. This was a prospective longitudinal study of 20 women at 25–34 weeks of gestation. One-hour recordings of FHR and fetal movements were made on each of five successive days in the morning and afternoon. Betamethasone was administered on day 0 and day 1.Results. We found no reduction of FHR variation on days 2 and 3 in the morning. In contrast, in the afternoon a reduction of FHR variation occurred on day 2. Time courses of fetal body and breathing movements during the morning were not affected by betamethasone administration.Conclusions. Transient reductions in fetal movement and FHR variation after glucocorticoid administration are not observed in the morning. For fetal monitoring and especially for assessing trends in fetal heart rate variation and movements with time, morning recordings should be preferably used in the period around glucocorticoid administration.

Rhythm abnormalities of the fetus

The myocardium begins to contract rhythmically by 3 weeks post-conception as a consequence of the activity of spontaneously depolarising myocardial pacemaker cells of the embryonic heart, and its maturation continues...

Circadian clocks during embryonic and fetal development

Circadian rhythmicity is a fundamental characteristic of organisms, which helps ensure that vital functions occur in an appropriate and precise temporal sequence and in accordance with cyclic environmental changes. Living beings are endowed with a system of biological clocks that measure time on a 24-hr basis, termed the circadian timing system. In mammals, the system is organized as a master clock located in the suprachiasmatic nucleus (SCN) of the hypothalamus, commanding peripheral clocks located in almost every tissue of the body. At the cell level, interlocking transcription/translation feedback loops of the genes Bmal-1, Clock, Per1-2, and Cry1-2, named clock genes, and their protein products results in circadian oscillation of clock genes and of genes involved in almost every cellular function. During gestation, the conceptus follows a complex and dynamic program by which it is simultaneously fit to develop and live in a circadian environment provided by its mother and to prepare for the very different environment that it will experience after birth. It has been known for a number of years that the mother tells the fetus the time of day and season of the year, and that the fetus uses this information to set the phase of fetal and neonatal circadian rhythms. There is evidence that the maternal rhythm of melatonin is one of the time signals to the fetus. In the last few years, the study of the development of the circadian system has turned to the investigation of the oscillatory expression of clock genes and their possible role in development, and to answering questions on the organization of the fetal circadian system. Emerging evidence shows that clock genes are expressed in the oocyte and during early and late development in embryo/fetal organs in the rat and in a fetal primate. The data available raise the intriguing possibility that the fetal SCN and fetal tissues may be peripheral clocks commanded by separate maternal signals. The rapid methodological and conceptual advances on chronobiology may help to unravel how the developing embryo and fetus faces time in this plastic period of life.

Automatic detection of ultrasonic Doppler signal episodes resulting from fetal breathing movements

A method for automatic detection of fetal breathing movements has been proposed, based on the time-frequency structure of the corresponding continuous wave ultrasonic Doppler signals. The method uses spectral analysis of the envelope of the directional Doppler signal and cross-correlation analysis of both directional envelopes. Detection rule comprises the following criteria: presence of the peak in the envelope spectrum and of the adequate signal level in the frequency range corresponding to the fetal breathing rhythm, the peak value and the position limits of the peak of the cross-correlation coefficient of the both directional envelopes. The effect of the criteria setting on the rule performance and the tradeoff between the specificity and sensitivity was investigated. The rule is most sensitive to the threshold value of the cross-correlation coefficient of the envelopes. The limits of the position of this peak are crucial for the distinction between the breathing episodes and hiccups. The optimal settings of the criteria, resulting in average sensitivity and specificity exceeding, respectively, 0.70 and 0.80, are proposed.

The Actifetus System: A Multidoppler Sensor System for Monitoring Fetal Movements

Fetal heart rate (FHR) monitoring is a crucial part of monitoring at-risk pregnancies and labor. Its aim is to detect any abnormalities that might indicate acute fetal distress and a need for rapid treatment to avoid death or serious sequelae, including cerebral handicap. The use of fetal biophysical profiles in high-risk pregnancies (gravidic hypertension, in utero infection, etc.) helps to distinguish healthy fetuses from those with chronic conditions. Fetal biophysical profile scores have been developed that integrate five biophysical parameters, one of which is derived from the FHR. The major parameters detected are the rate of fetal movements, fetal tone, fetal breathing movement and amniotic fluid volume. All of those parameters except FHR are obtained by prolonged echographic observation and cannot be used routinely. We developed in this study a new multigate multitransducer pulsed Doppler system for survey of fetal behavior. Fast Fourier transform and autocorrelation function have been used for processing and analyzing ultrasonic Doppler signals generated by fetal movements. Several parameters are analyzed in each of the 12 × 5 = 60 Doppler gates: amplitude of signals reflected by moving fetal structures, velocity, direction and amplitude of displacement of fetal structure (heart, chest, limbs). From these parameters it is possible to calculate FHR and characterize fetal activity. Preliminary in vivo results obtained in 15 pregnant women (30 to 36 wk) are very encouraging but they have yet to be confirmed in future studies. These results also demonstrate the advantages of transducers designed for improved fetal movement detection. The algorithms needs to be precise enough to allow the Actifetus system to function in real time. We now have at our disposal some algorithms that succeed in quantifying FHR and fetal movements with a signal from a given sensor at a given depth. This study confirms the feasibility of monitoring fetal movements by the Actifetus system and demonstrates the importance of the characterization of fetal rhythms (and fetal behavior). The Actifetus system will serve as a new mean for studying fetal response to environment and detecting anomalies related to fetal suffering. (E-mail: ali.kribeche@med.univ-tours.fr)

Point:Counterpoint: Medullary pacemaker neurons are essential for both eupnea and gasping in mammals vs. medullary pacemaker neurons are essential for gasping, but not eupnea, in mammals

to the editor: Implicit in the commentaries concerning the possible role of medullary pacemakers in the neurogenesis of eupnea and gasping is one critical and recurring question: How are in vitro rhythms related to these classical patterns of automatic ventilatory activity? Suzue ([5][1]) considered

Fetal ECG: a novel predictor of atrioventricular block in anti-Ro positive pregnancies

Objective:Approximately 2.8% of pregnancies are Ro/La antibody positive. 3–15% of fetuses develop complete heart block (CHB). First-degree atrioventricular heart block (1° AVB) is reported in a third of Ro/La fetuses...

Festschrift for Dr. John M. Opitz: Pathogenesis of cardiac conduction disorders in children genetic and histopathologic aspects

Fetal dysrhythmias are usually transient. Abnormal fetal rates and rhythms during labor are "functional." Fetal dysrhythmias may be associated with congenital heart disease and fetal hydrops. Bradycardia is usually related to fetal distress; supraventricular tachycardia, atrial flutter, and atrial fibrillation may be associated with severe congestive heart failure. Ventricular fibrillation is rare in the fetus and infant and is usually associated with myocardial necrosis with perimembranous septal defect; the nonbranching atrioventricular (AV) bundle may have an aberrant position and result in cardiac arrhythmia. Wolff-Parkinson-White syndrome with conduction abnormalities and left ventricular hypertrophy (LVH) is due to an accessory pathway that bypasses the AV sulcus and results in faster conduction. Carnitine deficiency may be primary or secondary and may result in cardiac arrhythmia. Histiocytoid cardiomyopathy is characterized by cardiomegaly, incessant ventricular tachycardia, and frequently sudden death. Arrhythmogenic right ventricular dysplasia (ARVD) results in ventricular tachycardia and left bundle branch block. Noncompaction of the left ventricle predisposes to potentially fatal arrhythmias. Long Q-T syndromes (LQTS) are a heterogeneous group of disorders with many genetic mutations. Brugada syndrome is an autosomal dominant trait with right bundle branch block and ST elevation. Barth syndrome is an X-linked disorder with dilated cardiomyopathy, cyclic neutropenia and skeletal myopathy. Hypertrophic cardiomyopathy in infancy may be related to metabolic diseases, particularly glycogen storage diseases; the familial form predisposes to sudden death. Arrhythmias following cardiac surgery may occur after closure of a ventricular septal defect (VSD) or damage to the conduction system.

Early perinatal outcome in cases delivered through caesarian section following clinical diagnosis of severe foetal distress at Kenyatta National Hospital

To determine the value of clinical foetal distress in predicting early perinatal outcome. Prospective cohort study. Kenyatta National Hospital. Fifty eight newborns delivered via Caesarian section with a diagnosis of clinical foetal distress were compared with another group of 58 newborns delivered similarly, but without clinical foetal distress. Newborn acidemia was found in 71% of newborns with clinical foetal distress in contrast to 17% in newborns without foetal distress. Low Apgar score at one minute was noted in about 59% of newborns with foetal distress compared with 31% in newborns without foetal distress. Similarly, 24.1% of neonates with clinical foetal distress had low Apgar score at five minutes compared with 3.4% in those without foetal distress. Thirty one percent of newborns with clinical foetal distress were admitted to newborn unit for more than 24 hours due to respiratory distress or birth asphyxia compared to 17% of those without foetal distress. The incidence of morbidity and or mortality in newborns exposed to foetal distress was twice the one of newborns without foetal distress. The results obtained in this study agreed with those who consider intrapartum passage of meconeum and abnormal foetal heart rate and rhythm to signify clinical foetal distress that carries bad prognostic outcome. These two parameters should still be used to indicate foetal distress which requires immediate institution of supportive therapy and immediate delivery.

Fetal and Maternal Magnetocardiography During Flecainide Therapy for Supraventricular Tachycardia

Fetal magnetocardiography is a noninvasive technique capable of identifying fetal arrhythmias and can simultaneously characterize the cardiac rhythm of the mother and fetus. Three patients, two singleton pregnancies and one twin pregnancy, were admitted for evidence of fetal supraventricular tachycardia. Fetal magnetocardiography was used to monitor the effects of flecainide therapy on the fetus and mother. Two singleton pregnancy fetuses showed improved heart rate and cardiac rhythm within 1 week of the initial dosing. Maintenance dosages controlled the conditions thereafter. Flecainide slowed the supraventricular tachycardia in the twin subject, but magnetocardiography revealed maternal adverse effects necessitating termination of flecainide therapy. Magnetocardiography is a valuable tool for rhythm diagnosis and for monitoring the maternal and fetal cardiac rhythms in a patient undergoing flecainide therapy for fetal supraventricular tachycardia.

Maternal Melatonin Effects on Clock Gene Expression in a Nonhuman Primate Fetus

In the adult mammal the circadian system, which allows predictive adaptation to daily environmental changes, comprises peripheral oscillators in most tissues, commanded by the suprachiasmatic nucleus (SCN) of the hypothalamus. The external environment of the fetus is provided by its mother. In primates, maternal melatonin is a candidate to entrain fetal circadian rhythms, including the SCN rhythms of metabolic activity. We found in the 90% of gestation capuchin monkey fetus expression of the clock genes Bmal-1, Per-2, Cry-2, and Clock in the SCN, adrenal, pituitary, brown fat, and pineal. Bmal-1, Per-2, and the melatonin 1 receptor (MT1) showed a robust oscillatory expression in SCN and adrenal gland, whereas a circadian rhythm of dehydroepiandrosterone sulphate was found in plasma. Maternal melatonin suppression changed the expression of Bmal-1, Per-2, and MT1 in the fetal SCN. These effects were reversed by maternal melatonin replacement. In contrast, neither maternal melatonin suppression nor its replacement had effects on the expression of Per-2 and Bmal-1 or MT1 in the fetal adrenal gland or the circadian rhythm of fetal plasma dehydroepiandrosterone sulphate. Our data suggest that maternal melatonin is a Zeitgeber for the fetal SCN but probably not for the adrenal gland.

Development and pH sensitivity of the respiratory rhythm of fetal mice in vitro

In newborn and adult mammals, chemosensory drive exerted by CO2 and H+ provides an essential tonic input: without it the rhythm of respiration is abolished. It is not known, however, whether this chemosensory drive and the respiratory rhythm appear simultaneously during development. In isolated brainstem–spinal cord preparations from fetal mice, we determined at what stage of fetal life the respiratory rhythm appeared in third to fifth cervical ventral roots (phrenic motoneurons) and whether this fetal rhythm was sensitive to chemosensory inputs. A respiratory-like rhythm consisting of short duration bursts of discharges recurring at 2–16 min−1 was detected in two of nine embryonic day 13 fetuses; it was abolished by transection of the spinal cord between the first to second cervical segments and was phase-related to rhythmic activity from medullary units of the ventral respiratory group. At embryonic day 13, it coexisted with a slow rhythm (0.1–2.0 min−1) of long duration bursts of action potentials which was generated by the spinal cord. At later fetal stages, the respiratory-like rhythm became more robust and of higher frequency, while the spinal cord rhythm became less obvious. At all fetal stages, acidification of the superfusion medium from pH 7.5–7.2 or 7.4–7.3 or 7.4 to 7.2 increased the frequency of both the respiratory-like and the spinal cord rhythms. In addition, acidification reduced the amplitude of the integrated burst activity of the spinal cord rhythm of embryonic day 13–embryonic day 16 fetuses and the respiratory-like rhythm of embryonic day 17 and older fetuses. Our results indicate that the rhythms transmitted by phrenic motoneurons during fetal development are chemosensitive from early fetal stages. Through its effects on induction and patterning of the rhythm, chemosensory drive may play a role in activity-dependent formation of respiratory neural networks.

Active Management of Third Stage Labor Is Associated with a Lower Cord Blood Unit Volume.

Aim: It has been demonstrated that active management of third stage of labour (AMTSL) (prophylactic administration of a uterotonic agent, early cord blood clamping and controlled cord blood traction) reduces the risk of primary post partum haemorrhage compared with expectant (or physiological) management. However this strategy might decrease the cord blood unit (CBU) volume which is collected in order to be banked for therapeutic use. Knowing that efficacy of CBU transplantation correlates with CD34+ progenitor cells content (which is correlated with the collected volume of CBU), we conducted a retrospective study to analyse the impact of AMTSL on volume and CD34 progenitor's content of CBU.Material and Method: From Jan 1st 2001 to Oct 2nd, 2004 the maternity affiliated to the Besançon CBB performed 3838 CBU collections after normal deliveries. Different factors that might impact on CBU volume and CD34+ cell content were analysed: age, parity, and smoking habit of the mother, gestational age, type of initiation and duration of first labour stage, duration (from the beginning of labour to initiation of the pushing phase), time of the second stage of labour (from the initiation of pushing time to the birth of the baby), foetal cardiac rhythm (FCR) alterations during labour, type of delivery (assisted or not) and variables of the third stage of labour (AMTSL, uterine revision, primary post partum haemorrhage occurrence, placenta weight). Moreover, variables in relation with the baby were studied: sex, weight, Apgar score at 1 and 5 minutes. Each factor were submitted to a univariate analysis. Multivariate analysis was carried only onto factors significant after univariate analysis. Analysis concerning volume was performed on all 3838 CBU while analysis for CD34+ cells content was performed only on CBU with a volume > 80 ml (minimum volume required for banking in our CBB)Results: In univariate analysis, assisted initiation of first stage of labour (p=0.04), FCR modification during labour (p=0.01), uterine revision (p=0.01), primary post partum haemorrhage (p=0.01), gestational stage (p=0.0001), duration of second stage labour (P=0.0001), placenta and baby weight (both p=0.0001) instrumental expulsion (p= 0.0001) and male baby (p=0.01) were associated with higher CBU volume. Conversely, AMSTL (p= 0.01) and Apgar sore at 1 and 5 minutes (p=0.0007 and 0.004 respectively) were associated with lower CBU volume. In multivariate analysis, only assisted initiation of first stage of labour (p=0.02), primary post partum haemorrhage (p=0.0001), duration of second stage labour (P=0.003), placenta and baby weight (both p=0.0001) were associated with higher CBU volume. However, AMSTL (p= 0.03) and Apgar sore at 1 (p=0.003) were associated with lower CBU volume. Concerning CD34+ cells, in multivariate analysis, only maternal age (p=0.02), gestational stage (p=0.0001), FCR modification during labour (p=0.001), duration of second stage labour (p=0.0001), placenta and baby weight (respectively p= 0.001 and p=0.0001) were associated with higher CD34+ cells content in CBU. Conversely, only Apgar sore at 1 (p=0.0001) was associated with lower CD34+ cells content in CBU.Conclusion: AMSTL is associated with a low CBU volume but not with a low CD34+ cell count. In view of the know generalized use of AMSTL, such findings could have on impact on the determination of volume and CD34+ cell content threshold required for CBU banking.

Rhythmic Neuronal Discharge in the Medulla and Spinal Cord of Fetal Rats in the Absence of Synaptic Transmission

Spontaneous rhythmic neuronal activity is generated in the developing vertebrate nervous system. The patterned activity spreads diffusely throughout the fetal neuraxis. Here we demonstrate the ability of the fetal rat spinal cord and medulla to generate and transmit robust rhythmic patterns in the absence of synaptic activity. Regular rhythmic discharges were produced by fetal tissue bathed in low or zero [Ca(2+)](o) solution. The activity persisted in the presence of antagonists to neurotransmitter receptors that are known to mediate synaptic-mediated events associated with fetal rhythms. A combination of ventral root recordings and optical imaging using voltage-sensitive dyes demonstrated the extensive spread of rhythmic discharge in spinal cord and medullary neuronal populations of in vitro preparations. Whole cell recordings from medullary slices were performed to examine the ionic conductances and revealed the importance of persistent sodium conductances for generation of rhythmic activity in hypoglossal (XII) motoneurons. Rhythmic bursting in XII motoneurons persisted in the presence of gap junction blockers, although the amplitude of synchronized motor discharge recorded from nerve roots was diminished. We propose that nonsynaptically mediated conductances, potentially by extracellular ionic flux and/or ephaptic and electrotonic interactions mechanisms, act in concert with neurochemical transmission and gap junctions to promote the diffuse spread of rhythmic motor patterns in the developing nervous system.

Maternal Fluoxetine Infusion Does Not Alter Fetal Endocrine and Biophysical Circadian Rhythms in Pregnant Sheep

Depression during pregnancy is frequently treated with the selective serotonin reuptake inhibitor (SSRI), fluoxetine (FX), commonly known as Prozac (Eli Lilly & Co, Indianapolis, IN). FX potentiates serotoninergic neurotransmission and serotonin has been implicated in the regulation of circadian rhythms. We have therefore investigated the effect of chronic administration of FX on maternal and fetal circadian rhythms in sheep. Following an initial bolus dose of 70 mg FX, an 8-day continuous infusion of FX (n = 11, 98.5 microg/kg x d) was performed. Controls (n = 13) were treated with sterile water vehicle only. Maternal and fetal plasma melatonin and prolactin concentrations were determined every 3 hours for 24 hours and then every 6 hours for 24 hours beginning on the fourth day of infusion. FX treatment did not alter either the basal or circadian rhythms of either maternal or fetal plasma melatonin and prolactin concentrations. Fetal cardiovascular and behavioral state parameters were measured continuously. While the incidence of low-voltage (LV) electrocortical (ECOG) activity was significantly reduced in fetuses in the FX group, there was no effect of FX on the diurnal rhythms in fetal arterial pressure, heart rate, breathing movements, or behavioral state. These results show that maternal FX treatment does not result in significant alterations in maternal and fetal hormonal and behavioral circadian rhythms.

Transient Loss of the Diurnal Rhythms of Fetal Movements, Heart Rate, and Its Variation after Maternal Betamethasone Administration

Antenatal betamethasone administration to enhance fetal lung maturation is associated with transient reductions in fetal heart rate (FHR) variation, breathing, and body movements 2 d after the first dose (d 2). This study examines whether steroid administration affects the natural diurnal rhythms of fetal variables. Sixteen women at 27-32 wk of gestation received two doses of betamethasone 24 h apart. One-hour recordings of FHR, breathing, and body movements were made in the morning, afternoon, and evening of d 2, and again in the morning of d 3. Repeat recordings were obtained at 4-6 d later from 9/16 women. Maternal blood samples were obtained with each recording to determine ACTH and cortisol. No diurnal rhythm was present for FHR, FHR variation, breathing, and body movements on d 2. This resulted from suppression of the expected natural rise in body and breathing movements, and heart rate variation in the course of the day. Suppression of the diurnal rhythm of body movements depended on gestation (R = -0.89; p < 0.01). All variables showed diurnal rhythms 4-6 d later. Maternal ACTH and cortisol diurnal rhythms were completely suppressed on d 2. Four to six days later, the normal diurnal pattern was resumed, although absolute levels of ACTH and cortisol were still suppressed. We conclude that maternal betamethasone administration transiently abolishes the fetal diurnal rhythms of heart rate and its variation, breathing, and body movements.