Fetal Breathing Movements Research Articles

Predicting pH at birth in pregnancies with abnormal pulsatility index and positive end-diastolic velocity in the umbilical artery

Objectives: To identify potential associations between fetal surveillance tests and acidosis at birth in pregnancies with abnormal but positive end-diastolic velocity in the umbilical artery. Methods: A prospective case–control study [group 1: pH < 7.2; group 2: pH ≥ 7.2] including 46 fetuses with abnormal but positive end-diastolic velocity in the umbilical artery was conducted between February 2007 and March 2009. Outcome variables were evaluated by univariate analysis and compared between the two groups. Clinically relevant and statistically significant variables were analyzed by logistic regression. Results: Abnormal nonstress test, presence of deceleration, and absent fetal breathing movements were statistically significant. Logistic regression analysis revealed that fetal heart rate (FHR) deceleration in the nonstress test is the only predictor of fetal acidosis at birth (p = 0.024; OR = 8.2; 95%CI: 1.2–52). Conclusions: In fetuses with positive end-diastolic flow velocity, acute variables of the antenatal surveillance tests are correlated with acidosis at birth and FHR deceleration in the nonstress test is the only predictor of fetal acidosis.

Fetal cardiac autonomic control during breathing and non-breathing epochs: The effect of maternal exercise

We explored whether maternal exercise during pregnancy moderates the effect of fetal breathing movements on fetal cardiac autonomic control assessed by metrics of heart rate (HR) and heart rate variability (HRV). Thirty women were assigned to Exercise or Control group (n=15/group) based on the modifiable physical activity questionnaire (MPAQ). Magnetocardiograms (MCG) were recorded using a dedicated fetal biomagnetometer. Periods of fetal breathing activity and apnea were identified using the fetal diaphragmatic magnetomyogram (dMMG) as a marker. MCG R-waves were marked. Metrics of fetal HR and HRV were compared using 1 breathing and1 apneic epoch/fetus. The main effects of group (Exercise vs. Control) and condition (Apnea vs. Breathing) and their interactions were explored. Fetal breathing resulted in significantly lower fetal HR and higher vagally-mediated HRV. Maternal exercise resulted in significantly lower fetal HR, higher total HRV and vagally-mediated HRV with no difference in frequency band ratios. Significant interactions between maternal exercise and fetal breathing were found for metrics summarizing total HRV and a parasympathetic metric. Post hoc comparison showed no group difference during fetal apnea. Fetal breathing was associated with a loss of Total HRV in the Control group and no difference in the Exercise group. Both groups show enhanced vagal function during fetal breathing; greater in the Exercise group. During in utero breathing movements, the fetus of the exercising mother has enhanced cardiac autonomic function that may give the offspring an adaptive advantage.

Atypical Fetal Response to the Mother's Voice in Diabetic Compared With Overweight Pregnancies

To characterize fetal spontaneous heart rate changes and movements and auditory-elicited heart rate changes in fetuses in diabetic pregnancies compared with those in uneventful, overweight pregnancies. Spontaneous heart rate and movements and maternal voice-elicited heart rate changes were observed in 46 mother-fetal pairs (n = 14 gestational diabetic and n = 32 overweight prepregnancy) at 36 (±1) weeks gestational age. Fetal heart rate changes, body movements, and breathing movements were observed for 20 minutes while the mother was at rest. Subsequently, each fetus was presented with a 2-minute audio recording of the mother's voice using the following 6-minute procedure: 2 minutes no-voice baseline, 2 minutes voice presentation, and 2 minutes no-voice postvoice period; heart rate was recorded continuously. There were no differences in spontaneous heart rate changes, body movements, or breathing movements between the 2 groups. Fetuses in the overweight group showed an increase in the heart rate during the playing of their mother's voice, whereas fetuses in the diabetic group showed no response. Fetuses in overweight pregnancies responded to the mother's voice with an increase in the heart rate as has been reported previously in uneventful pregnancies. The lack of response to the mother's voice in fetuses in diabetic pregnancies may represent immature neural or auditory system development, an increased sensorineural threshold, and thyroid or iron deficiency.

770: Toll-like receptor gene family expression on maternal neutrophils is down-regulated in normal and preeclamptic pregnancies

are provided in table. There was no significant effect of acetaminophen on either fetal breathing or body movements when the data was expressed as number of activity episodes, total activity time, percent of activity time, or activity rate. In addition, there was no effect of acetaminophen when fetal breathing and body movements were combined into a single composite activity score. There were no differences in the proportion of fetuses demonstrating breathing or movement sufficient to achieve a normal biophysical profile score for that parameter, nor was their a difference in time required to achieve a normal score. CONCLUSION: Acetaminophen does not impact fetal breathing or body movements in humans when given at normally prescribed doses. Thus, assessment of fetal well-being using biophysical parameters should not be effected by maternal acetaminophen use.

769: Effect of acetaminophen on fetal activity

Prostaglandin compounds have been demonstrated to suppress fetal breathing and body movements in animal models, whereas prostaglandin inhibitors such as acetaminophen have been shown to stimulate both fetal activities. Although the use of prostaglandins during induction of labor has been found to decrease fetal activity in humans, minimal data exists regarding the effects of acetaminophen. The present study aimed to determine if maternal administration of acetaminophen impacts in-utero fetal activity in normal human pregnancies.

Hemodynamics of fetal breathing movements: the inferior vena cava

Based on the hypothesis that fetal breathing movements (FBM) enhance sections of the circulation to meet the needs of gas transport, we studied the effects of FBM on the fetal inferior vena cava (IVC), which transports blood with the lowest oxygen saturation in the fetal body. One-hundred and ten women with low-risk singleton pregnancies were included in a longitudinal study during the second half of pregnancy. Inner diameter, peak systolic velocity and time-averaged maximum blood velocity were measured in the IVC below the ductus venosus outlet during rest and FBM. Volume flow and pressure gradient were estimated in 55 observations of forced inspiratory movements at 36 weeks of gestation. The results are presented as mean and 95% CI of the mean. Based on 585 observations obtained during fetal rest and FBM, we found no difference in diameter, 0.42 (95% CI, 0.41-0.43) cm vs. 0.41 (95% CI, 0.39-0.42) cm, respectively, apart from during high-amplitude inspiratory movement, when the diameter was 0.15 (95% CI, 0.13-0.17) cm. The peak systolic velocity was different during rest and FBM, 34.0 (95% CI, 32.7-35.3) cm/s vs. 81.5 (95% CI, 76.2-87.5) cm/s, respectively, and correspondingly for time-averaged maximum velocity, 19.7 (95% CI, 18.9-20.5) cm/s vs. 37.2 (95% CI, 34.9-39.9) cm/s, respectively. Forced inspiratory movements at 36 weeks significantly reduced flow in the IVC compared with rest, 63.6 (95% CI, 44.4-88.1) mL/min vs. 186.0 (95% CI, 142.8-238.1) mL/min, respectively. The pressure gradient increased 14-fold during forced inspiration, from 0.64 to 8.76 mmHg. High-amplitude fetal inspiration substantially constricts the abdominal IVC and creates a negative pressure in the chest. The IVC constriction withholds abdominal blood, thus temporarily giving way to other flows.

Blood flow in the foetal superior vena cava and the effect of foetal breathing movements

ObjectivesThe superior vena cava (SVC) drains venous blood from the upper foetal body, mainly the head. Data on the human foetus is scarce. Here we present reference values for the blood flow during the second half of pregnancy, and test the hypothesis that foetal breathing movements (FBM) enhance this flow. MethodsBased on a power calculation, 110 women with low-risk singleton pregnancies were recruited to a longitudinal study that included three sets of observations during the second half of pregnancy. Ultrasound was used to determine inner diameter, peak systolic blood velocity and time-average maximum velocities in the SVC during rest and respiratory activity. ResultsDuring the second half of pregnancy, SVC blood flow increased from 57.8mL/min (95% CI 51.7–64.3) to 221.5 (204.5–239.3). Based on 558 sets of observations obtained during foetal rest and FBM, we found an overall increase in diameter from 0.41cm (0.40–0.42) to 0.46 (0.44–0.48), peak systolic velocity from 35.9cm/s (34.9–37.0) to 62.2 (59.1–65.5), and time-averaged maximum velocity from 20.3cm/s (19.7–20.8) to 27.3 (26.1–28.6). This resulted in an overall 90% increase in mean SVC blood flow, from 108.1mL/min (98.8–117.9) at rest to 205.9 (183.2–230.5) during FBM. ConclusionThe blood flow in the SVC increases during the second half of pregnancy and is substantially augmented during FBM. Since high-amplitude FBM additionally reduces flow in the inferior vena cava, the net effect is a prioritised venous drainage from the foetal head enhancing the washout of CO2 in that area, which also contains the chemoreceptors.

OC22.04: Fetal breathing movements increase venous drainage through the superior vena cava

OC22.04: Fetal breathing movements increase venous drainage through the superior vena cava

Sonographic study of the relationship between gestational diabetes mellitus and fetal activity

Objective: To evaluate the relationship between gestational diabetes mellitus (GDM) and fetal activity. Materials and methods: We prospectively studied 18 pregnant patients with GDM and 20 pregnant patients with normal glucose screening test. An ultrasound equipmentwas used to perform a 30 min transabdominal sonographic recording for each patient. Each ultrasound exam was recorded using a DVD recorder. Fetal activity was analyzed using duration and number of episodes of fetal breathing and body movements. The recordings were analyzed using a stopwatch in order to accurately evaluate each recording. The data was statistically analyzed using the parametric and non-parametric t-test. Results: The results of the study indicated that there was a significant correlation (p = 0.007) between the duration of fetal breathing movement and GDM. Fetuses of mothers suffering from GDM had a significantly longer duration of fetal breathing movements compared with fetuses of non diabetic mothers. In addition, the total duration of fetal activity (time of fetal body movements plus fetal breathing movements) was significantly higher (p = 0.005) in GDM compared with non GDM pregnancies. The difference in fetal body movements between GDM and normal pregnancies was not statistically significant. Conclusion: The results of this study support the hypothesis that GDM has a direct influence on fetal activity. The significance of this finding should be further evaluated.

Automatic identification of fetal breathing movements in fetal RR interval time series

Fetal breathing movements are associated with respiratory sinus arrhythmia (RSA). We present an algorithm which processes RR interval time series in the time and frequency domain, identifying spectral peaks with characteristics consistent with fetal RSA. Tested on 50 data sets from the second and third trimester, the algorithm had a sensitivity of 96.1%, false positive rate 35.7%, false negative rate 3.9%. The characteristics of automatically and visually identified episodes were very similar and corresponded the expected changes over gestation. The method is suited for easy and reliable identification of fetal breathing movements.

Characterization of the fetal diaphragmatic magnetomyogram and the effect of breathing movements on cardiac metrics of rate and variability

Breathing movements are one of the earliest fetal motor behaviors to emerge and are a hallmark of fetal well-being. Fetal respiratory sinus arrhythmia (RSA) has been documented but efforts to quantify the influence of breathing on heart rate (HR) and heart rate variability (HRV) are difficult due to the episodic nature of fetal breathing activity. We used a dedicated fetal biomagnetometer to acquire the magnetocardiogram (MCG) between 36 and 38 weeks gestational age (GA). We identified and characterized a waveform observed in the raw data and independent component decomposition that we attribute to fetal diaphragmatic movements during breathing episodes. RSA and increased high frequency power in a time-frequency analysis of the IBI time-series was observed during fetal breathing periods. Using the diaphragmatic magnetomyogram (dMMG) as a marker, we compared time and frequency domain metrics of heart rate and heart rate variability between breathing and non-breathing epochs. Fetal breathing activity resulted in significantly lower HR, increased high frequency power, greater sympathovagal balance, increased short-term HRV and greater parasympathetic input relative to non-breathing episodes confirming the specificity of fetal breathing movements on parasympathetic cardiac influence. No significant differences between breathing and non-breathing epochs were found in two metrics reflecting total HRV or very low, low and intermediate frequency bands. Using the fetal dMMG as a marker, biomagnetometry can help to elucidate the electrophysiologic mechanisms associated with diaphragmatic motor function and may be used to study the longitudinal development of human fetal cardiac autonomic control and breathing activity.

Bio-magnetic signatures of fetal breathing movement

The purpose of fetal magnetoencephalography (fMEG) is to record and analyze fetal brain activity. Unavoidably, these recordings consist of a complex mixture of bio-magnetic signals from both mother and fetus. The acquired data include biological signals that are related to maternal and fetal heart function as well as fetal gross body and breathing movements. Since fetal breathing generates a significant source of bio-magnetic interference during these recordings, the goal of this study was to identify and quantify the signatures pertaining to fetal breathing movements (FBM). The fMEG signals were captured using superconducting quantum interference devices (SQUIDs) The existence of FBM was verified and recorded concurrently by an ultrasound-based video technique. This simultaneous recording is challenging since SQUIDs are extremely sensitive to magnetic signals and highly susceptible to interference from electronic equipment. For each recording, an ultrasound-FBM (UFBM) signal was extracted by tracing the displacement of the boundary defined by the fetal thorax frame by frame. The start of each FBM was identified by using the peak points of the UFBM signal. The bio-magnetic signals associated with FBM were obtained by averaging the bio-magnetic signals time locked to the FBMs. The results showed the existence of a distinctive sinusoidal signal pattern of FBM in fMEG data.

Development of Fetal Movement between 26 and 36-Weeks’ Gestation in Response to Vibro-Acoustic Stimulation

Background: Ultrasound observation of fetal movement has documented general trends in motor development and fetal age when motor response to stimulation is observed. Evaluation of fetal movement quality, in addition to specific motor activity, may improve documentation of motor development and highlight specific motor responses to stimulation. Aim: The aim of this investigation was to assess fetal movement at 26 and 36-weeks gestation during three conditions (baseline, immediate response to vibro-acoustic stimulation (VAS), and post-response). Design: A prospective, longitudinal design was utilized. Subjects: Twelve normally developing fetuses, eight females and four males, were examined with continuous ultrasound imaging. Outcome Measures: The fetal neurobehavioral coding system (FENS) was used to evaluate the quality of motor activity during 10-s epochs over the three conditions. Results: Seventy-five percent of the fetuses at the 26-week assessment and 100% of the fetuses at the 36-week assessment responded with movement immediately following stimulation. Significant differences in head, fetal breathing, general, limb, and mouthing movements were detected between the 26 and 36-week assessments. Movement differences between conditions were detected in head, fetal breathing, limb, and mouthing movements. Conclusion: Smoother and more complex movement was observed with fetal maturation. Following VAS stimulation, an immediate increase of large, jerky movements suggests instability in fetal capabilities. Fetal movement quality changes over gestation may reflect sensorimotor synaptogenesis in the central nervous system, while observation of immature movement patterns following VAS stimulation may reflect movement pattern instability.

Fetal breathing is associated with increased umbilical blood flow

In humans, fetal breathing movements affect blood velocities in the umbilical vein and artery, but it is not known whether fetal respiratory activity is associated with increased fetal blood flow through the placenta. We therefore tested this hypothesis in the present study. One-hundred and ten women with low-risk singleton pregnancies were each examined three times by ultrasound during the second half of pregnancy. Fetal heart rate, umbilical artery blood velocity, umbilical vein diameter and blood velocity, and umbilical blood flow at the placental end were determined during fetal rest and fetal respiratory movements. Based on 330 observations obtained during fetal rest or breathing activity, no difference was found in the mean fetal heart rate (beats per minute (bpm)) during rest compared with breathing (142 bpm vs. 142 bpm, respectively). Although fetal breathing affected the umbilical artery waveform, there was no difference in the mean time-averaged maximum velocity between rest and breathing: 26.6 (95% CI, 25.1-28.3) cm/s vs. 28.9 (95% CI, 27.2-30.7) cm/s, respectively. The umbilical vein was 27% greater in cross-sectional area and the blood velocity 9% higher during breathing, resulting in a 42% increase in mean umbilical blood flow: 121.8 (95% CI, 109.5-135.0) mL/min at rest vs. 173.0 (95% CI, 158.0-188.6) mL/min during breathing. Venous velocity was calculated from recordings of mean duration 3.7 s at rest and 6.2 s of respiratory activity. Gestational age did not influence the relationship. Fetal breathing is associated with increased umbilical blood flow during the second half of pregnancy. Umbilical vein distension during breathing suggests active endocrine regulation.

Dry Lung Syndrome: A Distinct Clinical Entity

Infants with preterm prolonged rupture of membranes can present with immediate onset of pulmonary insufficiency and need aggressive ventilatory support. Dry lung syndrome remains an under-recognised clinical entity and very few cases are reported in the literature, though a working definition has been previously proposed. The proposed underlying etiopathogenesis for this is functional hypoplasia of the lung where higher than usual ventilatory pressure for initial 1-2days can improve oxygenation. This study presents two cases which had similar antenatal and immediate postnatal course, but had diametrically opposite outcomes. Strategies to optimise outcomes in the setting of early premature rupture of the membranes should include antenatal assessment of mothers with monitoring of the liquor volume as well as the strength of foetal breathing movements, in-utero transfer with delivery in perinatal centres and attendance by neonatal staff of appropriate experience.

The neural and vascular effects of killed Su-Streptococcus pyogenes (OK-432) in preterm fetal sheep.

Fetal exposure to inflammatory mediators is associated with a greater risk of brain injury and may cause endothelial dysfunction; however, nearly all the evidence is derived from gram-negative bacteria. Intrapleural injections of OK-432, a killed Su-strain of Streptococcus pyogenes, has been used to treat fetal chylothorax. In this study, we evaluated the neural and cardiovascular effects of OK-432 in preterm fetal sheep (104 +/- 1 days, term 147 days). OK-432 (0.1 mg, n = 6) or saline vehicle (n = 7) was infused in the fetal pleura, and fetuses were monitored for 7 days. Blood samples were taken routinely for plasma nitrite measurement. Fetal brains were taken for histological assessment at the end of the experiment. Between 3 and 7 h postinjection, OK-432 administration was associated with transient suppression of fetal body and breathing movements and electtroencephalogram activity (P < 0.05), increased carotid and femoral vascular resistance (P < 0.05), but no change in blood pressure. Brain activity and behavior then returned to normal except in one fetus that developed seizures. OK-432 fetuses showed progressive, sustained vasodilatation (P < 0.05), with lower blood pressure after 4 days (P < 0.05), but normal heart rate. There were no changes in plasma nitrite levels. Histological studies showed bilateral infarction in the dorsal limb of the hippocampus of the fetus that developed seizures, but no injury in other fetuses. We conclude that a single low-dose injection of OK-432 can be associated with risk of focal cerebral injury in the preterm fetus and chronic central and peripheral vasodilatation that does not appear to be mediated by nitric oxide.

The role of CO2 and central chemoreception in the control of breathing in the fetus and the neonate

Central chemoreception is active early in development and likely drives fetal breathing movements, which are influenced by a combination of behavioral state and powerful inhibition. In the premature human infant and newborn rat ventilation increases in response to CO(2); in the rat the sensitivity of the response increases steadily after ∼P12. The premature human infant is more vulnerable to instability than the newborn rat and exhibits periodic breathing that is augmented by hypoxia and eliminated by breathing oxygen or CO(2) or the administration of respiratory stimulants. The sites of central chemoreception active in the fetus are not known, but may involve the parafacial respiratory group which may be a precursor to the adult RTN. The fetal and neonatal rat brainstem-spinal-cord preparations promise to provide important information about central chemoreception in the developing rodent and will increase our understanding of important clinical problems, including The Sudden Infant Death Syndrome, Congenital Central Hypoventilation Syndrome, and periodic breathing and apnea of prematurity.

Spontaneous in utero recovery of a fetus in a brain death‐like state

A healthy pregnant woman at 28 weeks of gestation was admitted with complete loss of fetal movement. Fetal heart rate (FHR) monitoring showed a fixed flat FHR pattern with no variability. Ultrasound examination revealed no fetal breathing movement. The fetus showed heart failure with extremely diminished left heart contractility. No abnormalities were found in the fetus. We assessed that the fetus was in a brain death-like status. After discussion, we decided not to deliver the baby but to monitor it carefully using FHR monitoring and continuous fetal ultrasound examinations, assuming the baby was dying or at least had little possibility of survival. However, 8 h after admission, FHR monitoring showed some variability and after another 12 h the fetus recovered completely. The baby was born at 35 week of gestation by cesarean section. The baby sustained some white matter brain damage, but with no significant clinical delay of motor development. This is a rare case of in utero recovery from a fetal brain death-like status.

Simultaneous MEG and Ultrasound Recording of Fetal Breathing Movement

Event Abstract Back to Event Simultaneous MEG and Ultrasound Recording of Fetal Breathing Movement Umit Ulusar1*, Rathinaswamy Govindan2, James Wilson1, Murphy Pamela2, Curtis Lowery2 and Hari Eswaran2 1 University of Arkansas at Little Rock, Graduate Institute of Technology, United States 2 University of Arkansas for Medical Sciences, Department of Obstetrics and Gynaecology, United States Bio-magnetic signals induced by fetal breathing movement (FBM) are interfering factors for the investigation of fetal magnetoencephalography (fMEG) and magnetocardiography. We developed a novel framework to identify FBM signal in the bio-magnetic recordings. Using a 151 magnetic sensor array system and a portable ultrasound device, simultaneous fMEG and sonographic recordings were performed for 11 to 30 minutes duration on six fetuses ranging between 35 and 37 weeks gestational age. The fMEG data were sampled at a rate of 312.5 Hz using a bandwidth set for 0-100 Hz. The interfering maternal cardiac signals were removed by the signal space projection technique. Ultrasound video was saved in MPEG format with 30 frames per second and 640 x 480 pixel resolution. The ultrasound images were processed using Sticks filter [1] for the elimination of the speckle noise and with horizontal Sobel filter for the edge enhancement. We obtained fetal movement signal by tracing the movement of the boundary defined by the fetal thorax spanning multiple frames. This signal was filtered using a 4th order Butterworth band-pass filter between 0.5 to 10 Hz with zero phase distortion. This resulted in a time series sampled at the video frame rate that represents the temporal behavior of the fetal thorax. Finally, to identify the MEG sensors containing the FBM, we used spectral coherence. The coherence was calculated between the MEG data and FBM signal obtained with ultrasound image processing on a window length of 1 minute with 4-second slides. The fMEG sensors that displayed statistically significant coherence were identified as the ones that contain the FBM signal.This study showed the feasibility of simultaneously recording fMEG and ultrasound. In future, the data observed with the identified sensors can be used to characterize the bio-magnetic signal of the FBM.

Study of fetal tracheal fluid velocities using Doppler ultrasound

Objective To characterize tracheal fluid flow during fetal breathing movements by Doppler ultrasound. Study design To use pulsed Doppler to measure flow velocity during inspiration and expiration in a cross-sectional study of 15 normal fetuses and determine the correlation, if any, between flow velocity and gestational age. Results Cyclic respiratory profiles – both regular and irregular – were observed. Intratracheal flow velocity was very elevated during inspiration, ranging from 10 to 80 cm/s and from 5 to 20 cm/s during expiration. Conclusion This technique enables the noninvasive semiquantitative evaluation of fetal breathing movements. This Doppler application opens the field for future studies to characterize the extent of pulmonary hypoplasia.