Behavioural states and Doppler velocimetry of the renal artery in the near term human fetus

Transition of fetal behavioural state 1F to 2F coincides with cardiovascular changes measured by Doppler velocimetry e.g. a decrease in pulsatility index (PI) in the internal carotid arteries and in the descending aorta, indicating redistribution of blood flow. Recently, we reported a considerable reduction in fetal urine production rate of 47% during fetal behavioural state 2F as compared to 1F. It was suggested that this reduction is caused by an increase in renal vascular resistance during 2F. Using Doppler ultrasound, flow velocity waveforms (FVW) of fetal renal arteries were recorded during behavioural states 1F and 2F. Fetal behavioural states 1F and 2F were assessed by recording fetal heart rate pattern, eye movements and body movements. The PI of the renal artery FVWs were calculated as an index of renal vascular resistance to blood flow. Fifteen healthy pregnant women between 36 and 40 weeks gestational age were studied and the relationship between fetal renal vascular resistance to blood flow and behavioural states was determined. We found that PI values in the renal arteries did not change relative to behavioural state 1F and 2F. These findings suggest that renal vascular resistance to blood flow is not appreciably different in 1F and 2F. This is in contrast with urine production rate which is almost reduced by half during 2F in the near term fetus.

A high uterine artery pulsatility index reflects a defective development of placental bed spiral arteries in pregnancies complicated by hypertension and fetal growth retardation

INTRODUCTION

The development of PIH is associated with a defective trophoblast invasion and conversion of spiral arteries into low-resistance uteroplacental arteries. Hypertension may then be a compensatory response to a defective uteroplacental perfusion. Similar mechanisms may operate in IUGR.

AIM

To compare uterine artery Doppler blood flow measurements with placental bed histology. The hypothesis was that placental bed vessel pathology plays a role for a raised flow resistance.

MATERIALS AND METHODS

After blood flow measurements, a placental bed biopsy was taken at CS in 26 complicated (study group) and 29 uncomplicated pregnancies (control group).

RESULTS

The uterine artery PI was significantly more often abnormally high in the study group compared with the control group, and also in hypertensive pregnancies compared with normotensive IUGR pregnancies. Physiological vessel changes were found in all controls but were absent in 76% of study cases. Physiological changes were significantly more often absent in SGA than in AGA newborns. Absence of physiological changes were significantly more often found in cases with an abnormally high PI.

DISCUSSION

The results link together circulatory and structural pathophysiological changes of the uteroplacental unit. A defective physiological conversion of the spiral arteries was associated with an increased uterine flow resistance.

CONCLUSION

This study gave further support for the existence of a triad of defective placental bed vessel maturation, increased uteroplacental flow resistance, and hypertension.

The effect of vibro-acoustic stimulation on fetal behavioral state organization

During the third trimester of pregnancy there is a gradual development of fetal behavioral states. These states are distinct and discontinuous modes of neural activity; they reflect a certain degree of maturity and/or integrity of the fetal brain and are homologous with those seen in newborn infants. Abnormal state development has been found in growth retarded fetuses and in fetuses of women with type-1 diabetes. Behavioral state organization is not easily influenced by external factors and most stimuli fail to induce a state change when the fetus is in quiet sleep (state 1F). However, fetuses do react to vibro-acoustic stimulation (VAS) with an electronic artificial larynx. This stimulus induces excessive fetal movements, prolonged tachycardia, disorganization of behavioral states, and state transitions normally not seen in healthy fetuses. The backgrounds for these excessive and unusual reactions are largely unknown. For the time being, it seems better not to use this device in clinical practice. In this review paper, data on the development of behavioral states and on fetal reactions to VAS are discussed.

The development of abnormal heart rate patterns after absent end-diastolic velocity in umbilical artery: analysis of risk factors

OBJECTIVES

Our objectives were to evaluate the time interval elapsing between the occurrence of absent end-diastolic velocity in the umbilical artery and either the development abnormal fetal heart rate patterns or delivery and to establish the maternal and fetal factors that may affect this interval.

STUDY DESIGN

Thirty-seven fetuses free of structural and chromosomal abnormalities in which the development of absent end-diastolic velocity in umbilical artery was evidenced by serial Doppler recordings were studied. At the first occurrence the following factors were considered: gestational age, presence of hypertension or preeclampsia, amniotic fluid index, severity of growth retardation, and 10 different Doppler indices calculated from extracardiac and intracardiac vascular districts. Actuarial statistical methods were applied, with the occurrence of antepartum late heart rate deceleration as the censoring variable.

RESULTS

The interval between the first occurrence of absent end-diastolic velocity in umbilical artery and delivery ranged from 1 to 26 days. Indications for delivery were the development of antepartum late heart rate decelerations in 23 fetuses (62.1%) and different maternal or fetal complications in the remaining 14 fetuses. Multivariate analysis revealed that gestational age and the presence of hypertension and pulsations in umbilical vein were the dominant factors in determining the length of this time interval.

CONCLUSION

The duration of the time interval between the occurrence of absent end-diastolic velocity in umbilical artery and abnormal heart rate pattern differs considerably among fetuses, and it is mainly determined by gestational age and presence of maternal hypertension and pulsations in umbilical vein.

Recent advances in the Doppler study of early fetomaternal circulation

Transvaginal color Doppler has enabled precise investigation of feto-maternal circulation in early pregnancy. Decrease of peripheral impedance, as well as increase of blood flow velocity was found in all segments of the uteroplacental circulation with gestational age. The same finding was observed in umbilical artery, fetal aorta and intracranial blood vessels. A significant decrease of vascular impedance in cerebral blood vessels exists earlier than in fetal aorta or umbilical artery which could be explained by the establishment of cerebral autoregulation mechanisms which ensure adequate oxygen and glucose supply to embryonic brain. There was no significant difference for RI values of luteal blood flow from the 6th to the 12th gestational week. No difference was found between RI values of luteal blood flow in normal and ectopic pregnancy. In threatened, incomplete and missed abortions RI of luteal blood flow was significantly higher in comparison with normal pregnancy. It seems that in the group of patients with threatened abortion, follow up of the luteal flow might give some prognostic value. No difference in peripheral impedance and blood flow velocity of the uteroplacental blood vessels was found between women with normal pregnancies and women with threatened abortions and normal pregnancy outcome. There was no significant difference in terms of RI and PSV in uteroplacental blood vessels between women with threatened abortion and normal pregnancy outcome and women with threatened abortion whose pregnancy terminated with complete abortion and blighted ovum. In 46% of 21 women with visible retrochorionic hematoma RI in spiral arteries was higher and PSV was lower on the side of the hematoma. These values could be explained by compression of the wall of the spiral arteries caused by hematoma. In missed abortion the mean RI value of the uterine artery was lower than the mean value in normal pregnancy, but was not in spiral arteries. Some authors reported RI values in cases of missed abortions around and above the cutoff point value of 0.63. In blighted ovum RI in uterine and spiral arteries was lower in comparison to normal pregnancy, but in the other studies this was not the case. Increased blood flow in radial arteries in patients with pregnancy associated with uterine myomata could be explained by higher levels of estriol hormone metabolized in the placenta. Transvaginal color Doppler could be helpful in diagnosis and differentiation of the different forms of a gestational trophoblastic disease. It seems that this technique is a good substitute for pelvic angiography.(ABSTRACT TRUNCATED AT 400 WORDS)

Flow velocity waveforms in the ductus venosus, umbilical vein and inferior vena cava in normal human fetuses at 12-15 weeks of gestation

The objective was to determine the normal Doppler flow velocity waveform patterns in the human fetal ductus venosus, inferior vena cava and umbilical vein correlated with fetal heart rate, and to examine their reproducibility and their inter-relationship at 12 to 15 weeks of gestation. Cross-sectional recordings of 45 normal pregnant women were collected for a data reference range transvaginally and transabdominally depending on fetal size and position. Maximum flow velocity waveforms were obtained from the ductus venosus, the intra-abdominal part of the umbilical vein and inferior vena cava. Time-averaged velocities were calculated in all three vessels together with peak systolic, peak diastolic and time-averaged velocities in the ductus venosus and inferior vena cava. Doppler recordings in 21 other patients displayed good reproducibility. Continuous forward flow in the umbilical vein was associated with pulsatile systolic and diastolic forward flow in the ductus venosus. Retrograde flow was present only in the inferior vena cava. Mean time-averaged velocity (SD) in the ductus venosus was 28.8 (6.1) cm/s, in the umbilical vein 9.7 (2.9) cm/s and in the inferior vena cava 10.9 (2.5) cm/s. No correlation could be established between waveform parameters and fetal heart rate. Combined transvaginal and transabdominal Doppler ultrasound allows reproducible blood flow velocity recordings at venous level in early pregnancy. Relatively high velocities were observed in the ductus venosus compared with the umbilical vein and inferior vena cava. Differences in flow velocities in the ductus venosus and inferior vena cava suggest that little or no mixing of blood occurs, a situation well described in sheep.

Correlation of nocturnal increase in plasma oxytocin with a decrease in plasma estradiol/progesterone ratio in late pregnancy

OBJECTIVES

Our purpose was to determine whether plasma oxytocin concentrations show a daily rhythm.

STUDY DESIGN

Ten women between 37 and 39 weeks of gestation volunteered for the study. They were admitted 1 to 2 days before the experiment. Three blood samples were taken with 2-minute intervals each time, at 8 AM, 4 PM, and 12 midnight. Oxytocin, 17 beta-estradiol, progesterone, and cortisol were measured by radioimmunoassay with highly specific antibodies. Statistical analysis of variance by Friedman's test was followed by multiple range testing, and p < 0.05 was considered significant.

RESULTS

Significant daily rhythm was found for plasma cortisol, progesterone, and oxytocin and for the estradiol/progesterone ratio. Oxytocin showed a nocturnal peak and a strong negative correlation with the estradiol/progesterone ratio.

CONCLUSIONS

The daily rhythm in plasma oxytocin parallels the rhythm in uterine activity (shown by others), suggesting a causal relationship between the two. Both may in turn be related to the ratio of circulating estradiol and progesterone.

Doppler velocimetry and fetal heart rate studies in nephropathic diabetics

OBJECTIVES

Our objectives were to determine in pregnancies complicated by diabetic nephropathy (1) if impedance to flow in the uterine and umbilical arteries is normal and (2) if these fetuses are hypoxemic and acidemic and if they have decreased fetal heart rate variation and Doppler blood flow redistribution.

STUDY DESIGN

In a cross-sectional study at the Harris Birthright Research Centre for Fetal Medicine, London, serial assessment of fetal heart rate variation and Doppler velocimetry of the placental and fetal circulations was undertaken in six pregnancies complicated by diabetic nephropathy. In all cases cordocentesis was performed within 24 hours before delivery for the measurement of umbilical venous blood gases.

RESULTS

Cordocentesis demonstrated these fetuses to be hypoxemic and acidemic. The fetal heart rate variation was decreased; however, impedance to flow in the uterine artery was normal, and increased impedance to flow in the umbilical artery with evidence of blood flow redistribution was observed in only one case.

CONCLUSIONS

Fetal hypoxemia and acidemia in pregnancies complicated by diabetic nephropathy is not a consequence of impaired placental perfusion, and the degree of metabolic derangement may be obscured by the apparent normal growth and failure of these fetuses to demonstrate blood flow redistribution.

The relationship between the quantity and quality of prenatal movements in pregnancies complicated by intra-uterine growth retardation and premature rupture of the membranes

In 17 fetuses with intrauterine growth retardation (IUGR), we studied the quantity of general movements and fetal breathing movements both cross-sectionally and longitudinally. In IUGR fetuses, cross-sectional comparisons were made between the quantity of fetal movements and (1) the fetal clinical condition and (2) the quality of general movements. In addition, the quantity of fetal movements in IUGR was compared with that in uncomplicated pregnancies and in pregnancies complicated by premature rupture of the amniotic membranes. In IUGR, the quantity of general movements declined from 25 weeks gestation onwards, whereas the quantity of fetal breathing movements increased. Longitudinal assessment of these parameters was obtained in four cases and showed a decline of general movements. No relationship between prenatal longitudinal data and neonatal outcome could be observed. Relating the quantity of general movements and breathing movements to the fetal condition, growth retarded fetuses were divided into three groups according to fetal deterioration. 1. Normal amount of amniotic fluid and normal fetal heart rate patterns. 2. Reduced amount of amniotic fluid. 3. Abnormal fetal heart rate patterns. The quantity of general movements as well as that of breathing movements was low in group 3, compared to group 1. In group 2 only the quantity of breathing movements and not of general movements was low. A similar pattern was found in the relation with the quality of general movements observed during fetal deterioration. Cross-sectional analysis of median values (28-31 weeks gestation) did not reveal differences in the quantity of general movements when IUGR, normal pregnancies and premature rupture of the membranes (with or without oligohydramnios) were compared. The quantity of fetal breathing movements was significantly lower in pregnancies complicated by IUGR and by premature rupture of the membranes with oligohydramnios compared to those of normal pregnancies and premature rupture of the membranes without oligohydramnios. In uncomplicated IUGR, the quantity of general movements and breathing movements is in the same range as in normal uncomplicated pregnancies. Similar to the quality of general movements, the quantitative variables were related to the fetal condition. However, in contrast to the quality of general movements, the quantity of general movements and breathing movements showed a high inter- and intraindividual variation. Therefore, the results of this study discourage the use of quantitative aspects of general movements and breathing movements as reliable indicators of the neurological condition in the individual fetus.

Magnesium pyrrolidone carboxylate infusion reduces angiotensin II pressor response in pregnant women at risk for hypertension

OBJECTIVE

Our objective was to investigate the possible restoring action of magnesium on vascular sensitivity to angiotensin II in pregnancy.

STUDY DESIGN

We studied intraplatelet free calcium and the pressor response to angiotensin II in 10 primigravid women (28 to 32 weeks' gestation) at risk for pregnancy induced hypertension on the basis of altered uteroplacental blood velocity waveforms at 20 weeks' gestation, before and after the infusion of 1 gm of magnesium pyrrolidone carboxylate. After the effective pressor dose was achieved or a maximum of 32 ng/kg per minute was reached, we infused 1 gm magnesium pyrrolidone carboxylate and repeated the test. Intraplatelet free calcium was measured by means of fluorescent probes at the beginning and the end of both tests.

RESULTS

Six women were classified as refractory to angiotensin II and four as sensitive (effective pressor dose < 10 ng/kg per minute). After magnesium pyrrolidone carboxylate infusion, the four sensitive women became refractory and the effective pressor dose was significantly enhanced to 32 in all six refractory women. Intracellular free calcium increased significantly during the first angiotensin II infusion, whereas after magnesium pyrrolidone carboxylate administration it did not change significantly.

CONCLUSIONS

Magnesium pyrrolidone carboxylate enhances the vascular refractoriness and intracellular free calcium mediates the pressor response to angiotensin II in pregnancy.

Abnormal internal carotid and umbilical artery Doppler in the small for gestational age fetus predicts an adverse outcome

Doppler studies of the internal carotid and umbilical arteries were performed in 29 women admitted to the antenatal ward with a diagnosis of being small for gestational age. The primary aim of the study was to determine whether an abnormal internal carotid waveform was associated with a poor perinatal outcome defined as: fetal distress, acidosis at birth or perinatal death. A poor perinatal outcome occurred in 18 pregnancies including six perinatal deaths. There was a highly significant association between an abnormal internal carotid waveform and a poor outcome and this was particularly so at a gestational age of < or = 34 weeks where the sensitivity, specificity and predictive values were all 100%. No baby with a normal internal carotid waveform had a poor outcome. Abnormal umbilical waveforms tended to occur earlier in pregnancy than abnormal internal carotid waveforms and were also predictive of an adverse perinatal outcome. Whether this information should be used clinically is not clear as abnormal umbilical artery and internal carotid waveforms were sometimes present for weeks before delivery occurred for fetal reasons.

The effect of improvement of umbilical artery absent end-diastolic velocity on perinatal outcome

OBJECTIVES

The purpose of this study was to analyze cases in which antenatal improvement of absent fetal umbilical artery end-diastolic velocity was detected and to correlate improvement with perinatal outcome.

STUDY DESIGN

Forty cases of umbilical artery absent end-diastolic velocity in singleton pregnancies were retrospectively reviewed. Maternal characteristics and perinatal outcomes were compared in cases where improvement of end-diastolic velocity was diagnosed and those in which no improvement was detected.

RESULTS

Eleven cases of absent end-diastolic velocity showed antenatal improvement and were associated with more advanced gestational age at delivery, longer diagnosis-to-delivery interval, larger birth weights, and a lower incidence of neonatal death than those fetuses without antenatal improvement.

CONCLUSION

Improvement of umbilical artery absent end-diastolic velocity can occur and is associated with improved pregnancy outcome when compared with patients without antenatal improvement of diastolic velocity.

Normal auditory brain stem evoked responses in infants of diabetic mothers

Auditory brain stem responses potentials were recorded from 71 newborns within the first 2 weeks after birth; conceptional age ranged from 37 to 41 weeks. Thirty-nine newborns were infants of diabetic mothers (IDMs) (17 White A, 22 White B-D) and 32 healthy term newborns served as control group. IDMs with additional high risk for cochlear or brain stem integrity were excluded. Birthweight for gestational age was significantly higher for IDMs. No differences in auditory brain stem responses wave latencies or amplitudes were observed between healthy infants of the control group and IDMs.

The relationship between heart rate and eye movement in the human fetus at 38-40 weeks of gestation

The purpose of this study was to compare two different methods for assessing fetal heart rate (FHR)--fetal eye movement (FEM) synchronization: (1) periods of high (HV) and low (LV) variability in the FHR and the presence (EM) and absence (NEM) of FEM were determined by visual inspection and the degree of association between FHR and FEM was assessed in terms of the fraction of study time for which no periods of LV-NEM and HV-EM could be identified; and (2) the maximum cross-correlation coefficient (rmax) and the lag at rmax (Lmax) were determined by direct computer analysis of FHR and FEM data for each fetus. Twenty normal human fetuses between 38 and 40 weeks of gestation were examined for a total of 2051 min (mean 103 min, range 72-150 min). In general, the state HV-EM was observed approximately twice as often as was the state LV-NEM; neither of these two states could be identified during 12.4% of the study time. The coefficient rmax was calculated assuming a sliding 3-min moving window, using either the average FHR (mean 0.53, range 0.31-0.85) or the variability in the FHR (mean 0.52, range 0.18-0.77). No relationship was found between rmax and Lmax calculated using the mean FHR and the fraction of time for which no state could be identified (P = 0.995). When the cross-correlation analysis was performed using FHR variability, a statistically significant relationship was found between the periods of no coincidence (of states LV-NEM and HV-EM) and rmax and Lmax (r2 = 0.32; P = 0.04).(ABSTRACT TRUNCATED AT 250 WORDS)

Perinatal development of human circadian rhythms: role of the foetal biological clock

The development of circadian rhythms and the neuronal mechanisms underlying their generation (particularly the suprachiasmatic nucleus of the hypothalamus) were reviewed. Based on perinatal animal studies and data from human foetuses and/or preterm infants it was concluded that human circadian rhythms are present as early as at 30 weeks of gestation. The significance of the mother and/or the environment regarding the entrainment of the "endogenous" foetal biological clock was emphasized.

The temporal relationship between the onset of rapid eye movement period and the first micturition thereafter in the human fetus with advance in gestation

The objective of this study was to investigate whether micturition occurs, temporally related to the onset of the rapid eye movement (REM) period, in the human fetus. The study was made on 139 fetuses at 33-36 weeks and 153 at 37-41 weeks gestation. The discrepancies between the expected (F(exp)) and observed (F(obs)) frequencies of time lag between the onset of the REM period and the first micturition thereafter were assessed using the goodness-of-fit test. At 33-36 weeks gestation, there was no statistical difference between F(obs) and F(exp) (P greater than 0.05). At 37 weeks onwards, however, significant differences were noted between F(obs) and F(exp) (P less than 0.005). Seventy-two percent of all micturitions occurred within eight minutes after the onset of the REM period. This indicates that there is a temporal relationship between the onset of the REM period and the first micturition thereafter, at term, during 37-41 weeks of gestation.

The development of ultradian rhythms in the human fetus

OBJECTIVE

Our objective was to determine the normal sequence of neurobehavioral development in the human fetus between 14 weeks' gestation and delivery.

STUDY DESIGN

The study was performed by longitudinal ultrasonographic observation of 45 low-risk singleton fetuses.

RESULTS

During the first half of the midtrimester there was a high rate of spontaneous movement that appeared randomly distributed. By the end of that trimester an increase in the duration of intervals of quiescence resulted in activity appearing cyclically distributed, with the duration of quiet cycles progressively increasing to term. Fetal mouthing and breathing were linked with cyclic behavior from the time of their emergence. Fetal heart rate pattern A could be recognized from around 32 weeks, due to a reduction in baseline variability in quiet cycles after 30 weeks, whereas pattern B could be recognized several weeks earlier. From the time cyclic behavior and heart rate patterns could be recognized, intervals of coincidence of the fetal behavioral state variables increased progressively with advancing gestation.

Longitudinal measurements of fetal heart rate (FHR) monitoring in second trimester

We investigated the possibility of clinical diagnosis of preterm fetal well-being in the second trimester using the duration of LTVs of less than 4.5 beats/min and characteristic FHR acceleration. Fetuses between 24 and 32 weeks gestation, unlike near-term fetuses are seldom quiet and therefore the prolonged absence of fetal movement may be the best indicator of a sick fetus at these gestational ages. The amplitude and duration of the acceleration of the FHR were also clinically useful diagnostic tools for fetus well-being during the second trimester.

Color Flow Detection of Vein of Galen Malformation in Utero

A vein of Galen malformation in an arteriovenous malformation that may cause a variety of cardiovascular and neurologic sequalae. Color flow Doppler is an accurate and fast method of diagnosing a vein of Galen malformation in utero. Early detection may improve the prognosis for these infants.

Transvaginal Color Doppler Ultrasonography in the Evaluation of Placental Circulation

Transvaginal color Doppler sonography has provided the capability to qualitatively evaluate blood flow in small branches of the uterine arteries, umbilical cord arteries, and intraplacental fetal arteries in early pregnancy. Accurate identification of these small vessels and analysis of their flow characteristics have improved our understanding of the physiology and pathophysiology of early pregnancy that alters the umbilicaluteroplacental circulations. Further development of this technique may help to predict fetal outcome in highrisk pregnancies and in pregnancies with complications, such as intrauterine growth retardation, preeclampsia, and trophoblastic invasion.

Inferior vena cava flow velocity waveforms in appropriate- and small-for-gestational-age fetuses

Reference ranges of inferior vena cava flow velocities were constructed from a cross-sectional study of 118 appropriate-for-gestational-age fetuses of 18 to 40 weeks of gestation. Blood flow velocity waveforms were recorded with color and pulsed Doppler equipment. Peak velocities and time velocity integrals were measured from inferior vena cava during systole, early diastole, and atrial contraction. The systolic-to-diastolic ratios between the peak velocities and time velocity integrals were calculated, and the reverse flow with atrial contraction was quantified as the percentage of forward flow (percentage of reverse flow). Recordings were also obtained from 79 small-for-gestational-age fetuses free of structural and chromosomal abnormalities, divided into three groups according to umbilical artery velocity waveforms: normal pulsatility index values (group 1, n = 26), pulsatility index greater than 95th percentile of our reference limits but presence of end-diastolic velocities (group 2, n = 33), and absence of end-diastolic velocities (group 3, n = 20). Fourteen fetuses of groups 2 and 3 were also studied at weekly intervals until the onset of antepartum late heart rate decelerations. In appropriate-for-gestational-age fetuses no changes were evident in peak velocities and time velocity integrals ratios, whereas the percentage of reverse flow significantly decreased with gestation. No significant differences were found between these values and those obtained in small-for-gestational-age fetuses of group 1. A significant increase of peak velocities and time velocity integrals ratios and of percentage of reverse flow was evidenced in fetuses of both group 2 and 3. The fetuses of groups 2 and 3 with a percentage of reverse flow above the 95% confidence interval showed a poorer perinatal outcome when compared with the fetuses of the same groups but with values inside the normal range. In the 14 fetuses longitudinally followed up until the onset of late heart rate decelerations a significant and progressive increase of peak velocities and time velocity integrals ratios and percentage of reverse flow was evidenced in spite of minimal changes in the pulsatility index from both umbilical artery and different peripheral fetal vessels. This study presents evidence that in small-for-gestational-age fetuses with abnormal Doppler-measured placental resistance the modified flow velocity patterns in the inferior vena cava seem to deteriorate progressively with advancing gestation.

The effect of intrauterine growth retardation on the quality of general movements in the human fetus

The effect of severe intrauterine growth retardation on the quality of general movements was studied longitudinally in 17 human fetuses. During the prenatal and postnatal periods, fetal movements were recorded by means of weekly 1 h ultrasound and video registrations. Neurological examinations were performed at 1, 3, 6 and 12 months after birth. No clear effect of uncomplicated intrauterine growth retardation could be detected on the quality of general movements. General movements became slow and small in amplitude (4/5) in cases where there was a reduction in the amount of amniotic fluid. Parallel to the onset of abnormal fetal heart rate patterns, general movements became poor in repertoire (7/7), while they were hardly discernible after further deterioration of the fetal condition (5/7). With the exception of 3 infants with cerebral haemorrhages, the quality of general movements observed just before and after birth was identical (13/16). In these infants, the quality of general movements as well as the results of the standardized neurological examination tended to normalize at 3 months and 1 year, respectively. Uncomplicated IUGR had no marked effect on the quality of general movements or on the results of the neurological examination at the age of 1 year.

Prediction of fetal outcome in small for gestational age fetuses: comparison of Doppler measurements obtained from different fetal vessels

Blood flow velocity waveforms were recorded from different vascular districts including umbilical artery, descending aorta, renal artery, internal carotid artery and middle cerebral artery in a population of 120 small for gestational age fetuses free from structural and chromosomal abnormalities. The pulsatility index from each vessel as well as the ratios between the pulsatility indices from peripheral and cerebral vessels were calculated and related to perinatal outcome. The pulsatility index of middle cerebral artery resulted the most efficient measurement to predict the development of perinatal adverse outcome when each vessel was considered singularly, however, better results were achieved when the ratios between pulsatility indices were related to perinatal outcome; this is mot evident for the ratio between the pulsatility indices of umbilical artery and middle cerebral artery. Our results suggest the usefulness of this ratio in differentiating small for gestational age fetuses at risk of unfavorable outcome.

Successful treatment of neonatal aneurysmal dilatation of the vein of Galen: the role of prenatal diagnosis and trans-arterial embolization

We report a neonate with aneurysmal dilatation of the vein of Galen diagnosed prenatally by color Doppler sonography and MRI at 37 weeks' gestation. The child was treated by transarterial embolization of micro-coils 2 and 8 days after birth. The aneurysmal dilatation of the vein of Galen markedly decreased after embolization and the patient is developing normally at 2 years 5 months of age. Prenatal diagnosis and early intervention by transarterial embolization produced in a good outcome in this patient.

Circadian rhythms and the suprachiasmatic nucleus in perinatal development, aging and Alzheimer's disease

Circadian rhythms are already present in the fetus. At a certain stage of pre-natal hypothalamic development (around 30 weeks of gestation) the fetus becomes responsive to maternal circadian signals. Moreover, recent studies showed that the fetal biological clock is able to generate circadian rhythms, as exemplified by the rhythms of body temperature and heart rate of pre-term babies in the absence of maternal or environmental entrainment factors. Pre-term babies that are deprived of maternal entrainment and kept under constant environmental conditions (e.g., continuous light) in the neonatal intensive care unit run the risk of developing a biological clock dysfunctioning. However, the fact should be acknowledged that at least in mice the development of the circadian pacemaker (i.e., SCN) does not depend on environmental influences (Davis and Menaker, 1981), although other data suggest that severe disruption of the maternal circadian rhythm indeed abolishes the circadian rhythm of the fetal SCN (Shibata and Moore, 1988). During aging and in particular in AD circadian rhythms are disturbed. These disturbances include phase advance and reduced period and amplitude, as well as an increased intradaily variability and a decreased interdaily stability of the rhythm. Among the factors underlying these changes the loss of SCN neurons seems to play a central role. Other contributory factors may be reduced amount of light, degenerative changes in the visual system and the level of activity and decreased melatonin.

Antenatal diagnosis of intrauterine growth retardation by ultrasound

Ultrasound estimation of fetal weight or ultrasound measurement of fetal abdomen alone enables identification of small-for-gestational-age fetuses. A prerequisite for this is a reliable dating of pregnancy, which is provided by a routine ultrasound screening in the first half of gestation. The fetal growth can be followed by serial fetometric measurements. As a standard, charts of intrauterine growth based on the ultrasonic measurement can be used. As a secondary diagnostic test for monitoring fetal health in pregnancies suspected of intrauterine growth retardation, Doppler ultrasound evaluation of fetal and uteroplacental hemodynamics provided useful for early detection of imminent fetal distress.

The effects of maternal hyperoxia on fetal breathing movements, body movements and heart rate variation in growth retarded fetuses

In hypoxemic intrauterine growth-retarded fetuses (IUGR) there is a reduction in the incidence of fetal movements and in fetal heart rate variation. A causal relationship with the impairment of fetal oxygenation has been suggested. In 16 IUGR fetuses and in 13 normally grown fetuses maternal hyperoxygenation was applied for 40 min to increase fetal PO2 levels. All IUGR fetuses had abnormal Doppler blood velocity waveforms of the umbilical artery suggesting an impaired uteroplacental exchange. The effect of hyperoxygenation on fetal breathing and body movements and on fetal heart rate was evaluated. In the IUGR fetuses there was a significant increase in fetal breathing and body movements and in heart rate variation during hyperoxygenation as compared to the preceding control period of 40 min. No significant changes in fetal breathing and body movements were found in the normally grown control fetuses. A surprising observation was the increase of the number of heart rate decelerations after discontinuation of the maternal hyperoxygenation. It is concluded that in IUGR fetuses the increase in fetal heart rate variation and the increase in the incidence of breathing and body movements during maternal hyperoxygenation substantiates the relationship between these variables and the oxygenation status of the fetus.

Influences on heart rate variability in spontaneously breathing preterm infants

To investigate the influence of maturational and physiological factors on heart rate variability in spontaneously breathing very preterm infants (n = 29) a multiparametric study was performed during the first 3 days of life in infants born at a gestational age below 33 weeks. Four times a day, RR-intervals, respiration curve and rate, transcutaneously measured blood gases and observed body movements were recorded while the infants were asleep. All data were stored simultaneously in a micro-computer. Non-invasively measured blood pressure and patency of the ductus arteriosus were documented as well. Four sets of short- (STV) and long term variability (LTV) indices were calculated. Both STV and LTV appeared to be significantly influenced by conceptional and postnatal age in the appropriate for gestational age infants. LTV was influenced by the behavioural state and body movements. During state coincidence 2 ('active sleep') LTV was influenced by respiratory rate and the variations in transcutaneous PO2. An effect of blood pressure or ductus patency could not be demonstrated.

The development of ultradian and circadian rhythms in premature babies maintained in constant conditions

Twenty very premature babies, born at 24-29 weeks gestation, have been studied while they were maintained in intensive care with continuous intravenous feeding and constant ambient lighting and temperature. Hourly records of insulated skin temperature and heart rate were made for a continuous period of 6-17 weeks, always starting the recording within 24 h of birth. The development of rhythms within the ultradian, circadian and infradian domains was sought by methods including maximum entropy spectral analysis and autocorrelation. Circadian and ultradian rhythms were present, but not regularly so; rather they appeared and disappeared erratically in successive weeks. As a consequence, the group as a whole did not show an increasing rhythmicity with chronological age. In some cases, babies were later placed in a ward in which the lighting was dimmed at night, and feeding by mouth at regular intervals was instituted. There was some evidence for increases in circadian and ultradian rhythmicity after these changes. These results enable inferences to be drawn as to the origin of fetal rhythms in the third trimester of pregnancy, as well as speculation to be made on the ontogeny of ultradian and circadian rhythms in the neonate.

Role of prenatal echocardiography in the study of hypertrophic cardiomyopathy in the fetus

The increased incidence of hypertrophic cardiomyopathy in children of diabetic mothers has already been demonstrated, but its prenatal diagnosis has not yet been extensively studied. The purpose of this prospective study was to evaluate the frequency, severity, and echocardiographic features of fetal hypertrophic cardiomyopathy in a population with several indications for prenatal echocardiography. From March 1987 to April 1991, 283 fetuses were submitted to comprehensive prenatal echocardiography, including M-mode measurements, cross-sectional imaging, Doppler studies, and color flow mapping. One hundred seventy-six were pregnancies complicated by previous or gestational diabetes. The diagnosis of disproportionate septal hypertrophy was made in 39 fetuses (mean septal thickness 7.12 +/- 1.6 mm), at a mean gestational age of 32 weeks. Diabetes mellitus was present in 36 of these pregnancies (92.3%). In four cases, nonimmune hydrops was detected. A systolic anterior motion of the mitral valve was present in three fetuses, but only one showed a gradient across the left ventricular outflow tract. Postnatal echocardiographic examination in 27 babies did not show false positivity. In ten cases, spontaneous regression of the septal hypertrophy was shown. There were three neonatal deaths, unrelated to the myocardial disease. We concluded that transient hypertrophic cardiomyopathy is a frequent entity, especially when associated with diabetes during gestation, being a potential cause for nonimmune hydrops. Fetal echocardiography is the method of choice for its prenatal diagnosis and should always be indicated in diabetic mothers.

Fetal cardiac function in intrauterine growth retardation

Blood-flow velocity waveforms are altered in several peripheral vascular beds of fetuses whose intrauterine growth is retarded because of placental insufficiency. We investigated these concomitant changes in cardiac function. Color and pulsed Doppler echocardiographic recordings were performed in 124 fetuses with intrauterine growth retardation. These fetuses were free of structural and chromosomal abnormalities and were characterized by increased umbilical artery resistance and reduced middle cerebral artery resistance. Twenty-four of these fetuses were also studied at weekly intervals until the onset of antepartum late heart rate decelerations. Blood-flow velocity waveforms were obtained from the aortic and pulmonary valves, and the following variables were measured: peak systolic velocity, time to peak velocity, the product of time velocity integral multiplied by heart rate, left and right cardiac output, and the right/left ratios of the product of time velocity integrals multiplied by heart rate and cardiac output. When compared with previously established norms, both aortic and pulmonary peak systolic velocities and pulmonary time to peak velocity were reduced; aortic time to peak velocity increased. Left cardiac output and the product of the aortic time velocity integral multiplied by the heart rate increased and right cardiac output and the product of the pulmonary time velocity integral multiplied by the heart rate decreased, resulting in reduced right/left ratios. In the 24 fetuses studied longitudinally, time to peak velocities and the right/left flow ratios remained stable. However, aortic and pulmonary peak velocities and cardiac output declined significantly in contrast to an expected rise with advancing gestation. The fall in cardiac output and aortic and pulmonary peak velocities was directly related to umbilical artery pH at birth. This study provides evidence of a modified cardiac function that seems to deteriorate progressively with the advancing gestation of fetuses with intrauterine growth retardation.

Doppler investigation of uteroplacental blood flow resistance in the second trimester: a screening study for pre-eclampsia and intrauterine growth retardation

OBJECTIVE

To assess the screening properties of a mid-trimester uteroplacental Doppler scan in a normal unselected population.

DESIGN

A cross-sectional study measuring an averaged resistance index (AVRI) from four sites (left and right uterine and arcuate arteries) with continuous wave Doppler ultrasound.

SETTING

Routine booking ultrasound, King's College Hospital, London.

SUBJECTS

977 women at 16-24 weeks gestation.

MAIN OUTCOME MEASURES

Intrauterine death, birthweight, pregnancy-induced hypertension (PIH), antepartum haemorrhage.

RESULTS

There was a 96.5% follow-up. Pregnancies with high AVRI values had a higher prevalence of proteinuric hypertension, placental abruption, small-for-gestational-age babies, and fetal loss. When AVRI was greater than 95th centile, the overall risk of pregnancy complications was 67%, and the risk of a severe complication was 25%. However, the sensitivity of the test for these complications was only 13% and 21% respectively. The risk for an individual woman with a high AVRI of developing a complication was increased by up to 9.8 times.

CONCLUSION

Although Doppler screening does detect a unifying defect leading to perinatal death, pre-eclampsia, growth retardation and placental abruption, the predictive values do not yet justify its introduction as a routine test.

Cerebral Doppler studies in the fetus and newborn infant

The goal of developing reliable commercial Doppler systems for measuring vessel diameter and velocity changes during the cardiac cycle appears to be near. Reaching this goal would enable us to obtain volume-flow information continuously. In animal experiments, continuous measurements of Doppler velocity, pressure, and flow add important insights into hemodynamic measurements. Incorporating Doppler methods in microcirculatory research could also provide a link between the microcirculatory and the macrocirculatory hemodynamic research. Although Doppler methods have been validated, Doppler findings in clinical research (using commercial systems) must be considered at best to reflect qualitative circulatory alterations indicating directions of change. Because of inherent technologic limitations and considerable intersubject and intrasubject variability, direct extrapolation of the numeric findings from one study to the other can lead to misleading conclusions. The Doppler results are also influenced by measurement conditions and equipment settings. However, Doppler-derived information can be used as an adjunct to clinical management in many of the diseases discussed above. As with any physiologic variable, serial measurements probably are of greater value than single measurements. With continued improvement in technology, Doppler methods hold promise of becoming an important adjunct in cerebral hemodynamic monitoring in perinatal-neonatal intensive care units.

Modulation by mu opioid antagonism of sleep and respiration in neonatal swine

Young (3-13 days) and older (26-34 days) piglets were instrumented aseptically for chronic recording of sleep/wake states (biparietal electrocorticogram, horizontal and vertical electrooculogram, submental muscle electromyogram (EMG)), heart rate, arterial pressure, pH and gas tensions, posterior cricoarytenoid and diaphragmatic EMG (EMGpca, EMGdi). After recovery from surgery, piglets underwent 1 h daily recordings for 5 consecutive days. Experimental sessions comprised control periods followed by study periods with CTOP (10-40 micrograms/kg i.v.), a somatostatin analogue with mu opioid antagonistic activity. In the young group, CTOP decreased percent time spent in active sleep (AS), increased heart rate during wakefulness, increased breathing frequency during transitional and quiet sleep (TS, QS) and decreased the duration of EMGdi activity during TS, QS and AS. In the older group, CTOP decreased the duration of EMGdi activity during QS. Changes in cardiorespiratory functions with age simulated those reported previously (Scott et al. (1990) Respir. Physiol. 80: 83-102). We conclude that, in early neonatal life, the mu opioid system influences both sleep pattern and respiratory timing, and that this influence diminishes with postnatal age.

Reproducibility of ultrasonic measurement of fetal cardiac haemodynamics

Two observers made independent estimates of volume flow across all four heart valves in 27 fetuses using a combination of cross-sectional and Doppler echocardiography. There were considerable discrepancies between observers in volume flow estimation arising from inconsistency both in cross-sectional and in Doppler measurements. One observer also produced a second estimate by making new measurements from the original recordings. There was considerable within-observer variability which was mainly due to errors in cross-sectional measurements. The problems of applying this technique to fetal cardiac haemodynamics are discussed.

Umbilical artery velocity waveforms in early pregnancy: a transvaginal color Doppler study

In a cross-sectional study, umbilical artery velocity waveforms were recorded in 214 low-risk pregnancies at 7 weeks to 16 weeks, menstrual age, by means of transvaginal color and pulsed Doppler ultrasonography. In all the cases studied, end diastolic velocities were absent until the 10th week. From this age onward end diastolic velocities were present in a percentage of pregnancies, progressively increasing with gestation and reaching 100% at 15 weeks. Similarly, the percentage of cardiac cycles in which end diastolic velocities were absent progressively decreased with advancing menstrual age. The normal range for the pulsatility index was constructed and a quadratic function was found to optimally fit its fall during gestation. No differences in pulsatility index values were found at these menstrual ages in 12 pregnancies that later developed intrauterine growth retardation and/or pregnancy-induced hypertension, suggesting that placental alterations causing abnormalities in umbilical velocity waveforms occur later in gestation.

Early detection of preeclampsia

The signs and symptoms of preeclampsia are usually apparent at a relatively late stage in pregnancy (late second to early third trimester). However, the disorder results from abnormal interaction between fetal and maternal tissue much earlier in pregnancy, between 8 and 18 weeks' gestation. During the past two decades numerous clinical, biophysical, and biochemical tests have been proposed for the early detection of preeclampsia. Some of these tests are simple, whereas others are invasive; some have been studied extensively, while others are still under clinical investigation. A review of the literature indicates considerable disagreement regarding the sensitivity and predictive values of the various tests studied. The reported differences in the predictive values of these tests may be attributed to one or more of the following: populations studied, definition and prevalence of the disorder, techniques and methodology used in performing these tests, etc. As a result, there is disagreement regarding the ideal screening test to be used for identifying patients for clinical trials dealing with prevention of the disorder.

The current status of maternal and fetal blood flow velocimetry

Significant progress has been achieved in regard to normative data for uteroplacental and fetal blood flow velocity and the factors which may affect these observations. Associations have been demonstrated between abnormal indices of maternal and fetal blood flow velocity and pregnancy-induced hypertension, fetal growth retardation, fetal blood gas measures, and intrapartum clinical fetal distress. However, in general, the predictive power is modest and no evidence has yet been provided to indicate that these measures can be used as a screening test in the general obstetric population. Continuing research is highly desirable. At the present time, the use of Doppler assessment of blood flow in pregnancy should be limited to the investigational setting.

Cardiac function in fetuses of type I diabetic mothers

Cardiac function was cross-sectionally studied by means of M-mode and Doppler echocardiography in 40 fetuses of mothers with well-controlled insulin-dependent diabetes at 20 to 38 weeks of gestation. These variables were measured: interventricular septal thickness, ratio between the peak velocities during early passive ventricular filling and active atrial filling at the level of the atrioventricular valves, peak velocities, and the time to peak velocity at the level of the ascending aorta and the pulmonary artery. The values obtained were compared with our reference limits for gestation. A significant increase of interventricular septal thickness that was unrelated to maternal glycosylated hemoglobin levels was evidenced. Early passive ventricular filling/active atrial filling ratios were significantly lower in fetuses of diabetic mothers than in control fetuses. These differences were significantly related to interventricular septal thickness. No significant modifications were found in either aortic or pulmonary peak velocities or in time to peak velocity values. These findings suggest that in spite of an adequate metabolic control an interventricular septal hypertrophy that affects cardiac diastolic function develops in fetuses of diabetic mothers.

Doppler velocimetry: critical analysis of umbilical, cerebral and aortic reference values

Cross-sectional reference standards of the umbilical flow velocity waveforms were investigated from 18 to 38 weeks of gestation on 482 normal pregnancies. A significant decrease in the pulsatility index (PI) and systolic/diastolic (SD) ratio was observed during gestation. This phenomenon was confirmed in a longitudinal study on 150 patients of the same population. The two slopes of cross-sectional and longitudinal data were not significantly different. A bimodal distribution of PI and S/D ratio was observed. Six per cent of data fell above the vast majority of cases. The dimension of the population studied allowed us to consider these findings not as outliers but as an interesting transient phenomenon of very low end-diastolic velocities which can occur in normal fetuses, without concomitant variations on the thoracic aorta and middle cerebral artery. Cross-sectional reference ranges were studied for these vessels on the same population from 26 to 38 weeks of gestation. A significant decrease in the PI of the middle cerebral artery was observed versus a significant increase in the PI of the thoracic aorta. These latter indices could be used to obtain indirect information on the normal redistribution of blood flow in the human fetus in the third trimester of gestation. However, the great variability observed should warn against the risks of a simplistic clinical use of these observations.