Reduced fetal movements and maternal medication - new pregnancy risk factors for neurodevelopmental disability in childhood

A case-control study was undertaken of 471 children on the Nottingham Special Needs Register (SNR) who were born in one of the two maternity units in the city between 1987 and 1993 (inclusive). Controls were selected as the next infant born at the same hospital following each index case. The aim of the study was to identify risk factors on the Nottingham Obstetric Database for a baby subsequently appearing on the SNR. Disability was analysed by both ICD-9 coding and functional assessment. Factors which independently and significantly predicted a child's likelihood of being on the SNR were breech presentation (adjusted odds ratio (OR) = 4.0), congenital abnormality (OR=4.9), intrapartum fetal distress (OR=1.7), fetal growth restriction (OR=2.0), socioeconomic deprivation (OR=1.8), prematurity (OR=2.2), reduced fetal movements (OR=2.5) and medication in pregnancy (OR=10.4). To our knowledge the last two factors have not previously been reported as risk predictors for neurodevelopmental disability.

Vascular endothelial cadherin and beta-catenin in human fetoplacental vessels of pregnancies complicated by Type 1 diabetes: associations with angiogenesis and perturbed barrier function

AIMS/HYPOTHESIS

Increased angiogenesis of fetoplacental vessels is a feature of pregnancies complicated by Type 1 diabetes mellitus, but the underlying molecular mechanisms are unknown. This investigation tests whether the diabetic maternal environment alters the phenotypic expression of placental vascular endothelial cadherin and beta-catenin, which have been implicated as key molecules in barrier formation and angiogenesis in the endothelium.

METHODS

Term placental microvessels from normal pregnancies (n=8) and from those complicated by Type 1 diabetes (n=8) were perfused with 76-Mr dextran tracers (1 mg/ml) and subjected to immunocytochemistry, immunoblotting and microscopy. Junctional integrity, localisation and phosphorylation were investigated along with total protein levels of vascular endothelial cadherin, beta-catenin and vascular endothelial growth factor. Stereological sampling and estimation tools were used to quantify aspects of angiogenesis and endothelial proliferation.

RESULTS

In the Type 1 diabetic placentae, junctional localisations of vascular endothelial cadherin and beta-catenin altered significantly, with more than 50% of microvessels showing complete loss of immunoreactivity and with no overall loss of total protein. Tracer leakage was associated with these vessels. There was a two- to three-fold increase in vessels showing junctional phospho-tyrosine immunoreactivity and hyperphosphorylated beta-catenin. Vascular endothelial growth factor levels were higher in these placentae. A four-fold increase in endothelial proliferation was observed, along with an increase in total length of capillaries without any change in luminal diameter.

CONCLUSIONS/INTERPRETATION

Molecular perturbations of vascular endothelial cadherin and beta-catenin occur in fetoplacental vessels of pregnancies complicated by Type 1 diabetes. Phosphorylation and loss of these molecules from the adherens junctional domains may be influenced in part by the elevated levels of vascular endothelial growth factor in the placenta. Perturbations of the junctional proteins may explain the observed breach in barrier integrity and may contribute to the mechanisms that drive proliferation and increases in capillary length.

Fetal learning: a prospective randomized controlled study

OBJECTIVES

To examine whether prenatal exposure to a music stimulus alters fetal behavior and whether this continues into the newborn period.

SUBJECTS AND METHODS

A prospective randomized control trial was conducted using an exposure learning model in 20 normal term pregnancies. Music was played to ten fetuses via a headphone on the maternal abdomen. Ten controls had the headphone without sound. All fetal studies took place within 72 h prior to elective delivery. All 20 newborns were exposed to the same music on days 3-5. Computerized assessment of fetal heart rate and activity was documented and neonatal behavioral states were recorded. Nonparametric statistical analysis was used.

RESULTS

For the first hour of study, exposed fetuses had higher mean heart rates (FHR) and spent more time exhibiting high FHR variation compared to unexposed fetuses, but neither of these differences was statistically significant. However, by the fourth hour the exposed fetuses not only demonstrated these two features but also exhibited more state transitions (P = 0.01) and higher FHR variation (P = 0.04) compared to unexposed fetuses. These effects were carried over into the neonatal period with prenatally exposed newborns manifesting more state transitions (P = 0.01) and spending a higher proportion of time in awake states (P = 0.05) when exposed to the same music stimulus.

CONCLUSION

Prenatal music exposure alters the fetal behavioral state and is carried forward to the newborn period. This suggests that a simple form of fetal programming or learning has occurred.

A comparison of fetal behaviour in term fetuses exposed to anticonvulsant medication with unexposed controls

OBJECTIVE

To compare behaviour in term fetuses exposed to anticonvulsants with unexposed controls.

DESIGN

An observational study.

SETTING

Pregnancy Assessment Centre, University Hospital, Nottingham, UK.

SAMPLE

Seventeen fetuses whose mothers were taking anticonvulsants and 94 fetuses whose mothers were on no medication between 28 and 41 weeks.

METHODS

Behaviour (fetal heart rate and activity) was recorded with the use of Doppler ultrasound. The duration of recording was 60 minutes or more in all but four recordings (minimum 49 minutes).

MAIN OUTCOME MEASURES

Behavioural criteria studied were: 1. the relative percentage time spent in low and high variation fetal heart rate patterns; 2. the duration and recurrence of fetal activity; 3. the number of accelerations in low and high fetal heart rate variation; and 4. the number of fetal behavioural state transitions.

RESULTS

The two groups were comparable in terms of maternal age, parity. birthweight, Apgar scores and absence of neonatal problems. There was less fetal activity in the anticonvulsant group, but this was only statistically significant at 33-36 weeks in fetal heart rate pattern B (equivalent to state 2F).

CONCLUSIONS

This study showed that fetuses exposed to anticonvulsant medication exhibited a trend of being less active. There were no other significant differences in behaviour. The data do not support the hypothesis of substantial differences in behaviour in fetuses exposed to anticonvulsants.

The information content of Doppler ultrasound signals from the fetal heart

Knowledge of the content of Doppler ultrasound signals from the fetal heart is essential if the performance of fetal heart rate (FHR) monitors based upon this technology is to be improved. For this reason instrumentation was constructed to enable the simultaneous collection of Doppler audio signals and the transabdominal fetal ECG (for signal registration), with a total of 22 recordings being made with an average length of around 20 minutes. These data demonstrate the transient nature of the Doppler audio data with wide variations in the signal content observable on a beat-to-beat basis. Short-time Fourier analysis enabled the content of the Doppler signals to be linked to six cardiac events, four valve and two wall motions, with higher frequency components being associated with the latter. This differing frequency content together with information regarding the direction of movement that can be discerned from Doppler signals provided a potential means of discriminating between these six events (which are unlikely to all contribute to the Doppler signal within the same cardiac cycle). Analysis of 100 records showed that wall contractions generate the most prominent signals, with atrial contraction recognisable in all records and ventricular wall contraction in 95% (although its amplitude is only around 30% of that of the atrial signal). Valve motion, with amplitudes between 15 and 25% that of the atrial wall signal, were visible in 75% of records. These results suggest means by which the six events that contribute to the Doppler signal may be distinguished, providing information that should enable an improvement in the current performance of Doppler ultrasound-based FHR monitors.

Computerized analysis of acute and chronic changes in fetal heart rate variation and fetal activity in association with maternal smoking

OBJECTIVE

To investigate the acute and chronic changes in fetal heart rate and fetal activity in association with maternal smoking by means of a computerized fetal behavior assessment program.

STUDY DESIGN

In 13 term nonsmokers and 13 term smokers, fetal behavior was analyzed for 2 consecutive periods of >60 minutes. In between these 2 periods, the smokers were allowed to smoke 1 cigarette, the nonsmokers were allowed a short break of comparable time span. Fetal heart rate variation and fetal activity were recorded by a single 1.5-MHZ ultrasound transducer. The percentage of time spent in low and high fetal heart rate variation and fetal activity were analyzed by computer before and after the short break for nonsmokers and before and after the smokers smoked the 1 cigarette. Smoking-induced changes in Doppler umbilical artery recordings were also investigated. Chronic exposure to cigarette smoke was objectively evaluated by measuring the carbon monoxide concentration in expired air in all participating women after breath holding.

RESULTS

Fetuses chronically exposed to cigarette smoke spent significantly more time in a low fetal heart rate variation pattern, while fetal activity was decreased both in high and low fetal heart rate variation periods. After maternal smoking, no acute changes were observed in fetal heart rate variation, yet a reduction in fetal activity was noted; however, this only reached statistical significance in periods of high fetal heart rate variation. No significant change in mean fetal heart rate was observed, yet a significant reduction in the frequency of accelerations was noted. Smoking caused an acute and transient increase in the mean pulsatility index in the umbilical artery.

CONCLUSION

The computer program was able to detect changes in fetal behavioral variables in association with acute and chronic smoking. These changes may be suggestive of altered neurodevelopmental maturation possibly resulting from chronic fetal hypoxemia. This computer program offers a real possibility that analysis of fetal behavioral variables can be brought into routine clinical practice. Incorporating an analysis of these behavioral variables into smoking cessation programs may render them more successful.

Computerised analysis of the fetal heart rate and relation to acidaemia at delivery

OBJECTIVE

To identify the individual features of the computerised analysis of the cardiotocograph that relate to arterial pH and base deficit at delivery.

DESIGN

Retrospective observational study.

SETTING

Teaching hospital labour wards.

PARTICIPANTS

679 women requiring continuous intrapartum fetal monitoring.

METHODS

Fetal heart and uterine contraction data were obtained using the Nottingham Fetal ECG monitor. Fetal heart rate patterns for the last half-hour preceding delivery were analysed using a computer algorithm developed for intrapartum application. The significance of the areas under receiver operator characteristic curves were calculated.

MAIN OUTCOME MEASURES

Umbilical arterial pH and base deficit at delivery.

RESULTS

Three parameters, fetal bradycardia, total deceleration area and the deceleration area after a contraction had receiver operator characteristic curves that significantly predict a low umbilical arterial pH and base deficit at delivery (areas under receiver-operator characteristic curves = 0.53, SD 0.01 P = 0.03; 0.60, SD 0.03 P = 0.002; 0.62 SD 0.04 P < 0.001, respectively). Tachycardia, accelerations and variability did not.

CONCLUSIONS

The individual components of the computerised analysis of the fetal heart rate that predict acidaemia at delivery are identified.

Compact long-term recorder for the transabdominal foetal and maternal electrocardiogram

Foetal heart rate (FHR) monitoring is a proven means of assessing foetal health during the antenatal period. Currently, the only widely available instrumentation for producing these data is based on Doppler ultrasound, a technology that is unsuitable for long-term use. For nearly a century, it has been known that the foetal electrocardiogram (FECG) can be detected using electrodes placed on the maternal abdomen. Although these signals suggest an alternative means of FHR derivation, their use has been limited owing to problems of poor signal-to-noise ratio. However, the eminent suitability of the transabdominal FECG for long-term FHR monitoring has suggested that perseverance with the technique would be worthwhile. The paper describes the design, construction and use of a compact, long-term recorder of three channels of 24 h antenatal transabdominal data. Preliminary use of the recorder in around 400 short recording sessions demonstrates that FHR records of equivalent quality to those from Doppler ultrasound-based instruments can be extracted from such data. The success of FHR derivation is, on average, around 65% of the recording period from around 20 weeks gestation (although this figure is reduced from around 28-32 weeks, and the success rates exhibit a wide range when individual subjects are considered). These results demonstrate that the technique offers, not only a means of acquiring long-term FHR data that are problematic to obtain by other means, but also a more patient-friendly alternative to the Doppler ultrasound technique.

Influenza virus infection in the second and third trimesters of pregnancy: a clinical and seroepidemiological study

OBJECTIVE

To determine whether maternal influenza virus infection in the second and third trimesters of pregnancy results in transplacental transmission of infection, maternal auto-antibody production or an increase in complications of pregnancy.

DESIGN

Case-control cohort study.

POPULATION

Study and control cohorts were derived from 3,975 women who were consecutively delivered at two Nottingham teaching hospitals between May 1993 and July 1994. A complete set of three sera was available for 1,659 women.

METHODS

Paired maternal ante- and postnatal sera were screened for a rise in anti-influenza virus antibody titre by single radial haemolysis and haemagglutination inhibition. Routine obstetric data collected during and after pregnancy were retrieved from the Nottingham obstetric database. Cord samples were tested for the presence of IgM anti-influenza antibodies, and postnatal infant sera were tested for the persistence of influenza-virus specific IgG. Paired antenatal and postnatal sera were tested against a standard range of auto-antigens by immunofluorescence.

MAIN OUTCOME MEASURES

Classification of women as having definite serological evidence of an influenza virus infection in pregnancy (cases) or as controls.

RESULTS

Intercurrent influenza virus infections were identified in 182/1,659 (11.0%) pregnancies. None of 138 cord sera from maternal influenza cases was positive for influenza A virus specific IgM. IgG anti-influenza antibodies did not persist in any of 12 infant sera taken at age 6-12 months. Six of 172 postnatal maternal sera from cases of influenza were positive for auto-antibodies. In all cases the corresponding antenatal serum was also positive for the same auto-antibody. There were no significant differences in pregnancy outcome measures between cases and controls. Overall, there were significantly more complications of pregnancy in the cases versus the controls, but no single type of complication achieved statistical significance.

CONCLUSIONS

Influenza infection in the second and third trimesters of pregnancy is a relatively common event. We found no evidence for transplacental transmission of influenza virus or auto-antibody production in pregnancies complicated by influenza infections. There was an increase in the complications of pregnancy in our influenza cohort.

Effects of gestational diabetes on junctional adhesion molecules in human term placental vasculature

AIMS/HYPOTHESIS

The aim of this study was to investigate whether gestational diabetes mellitus, which occurs in the microvascular remodelling phase of placental development, causes alterations in surface expression of tight and adherens junctional molecules involved in endothelial barrier function and angiogenesis.

METHODS

Term placenta, delivered by elective Caesarian section, from normal pregnancy (n = 5) and those complicated by gestational diabetes (n = 5) were perfusion-fixed and analysed by indirect immunofluorescence and confocal scanning microscopy. Using systematic random sampling, the surface expression of endothelial junctional proteins and the relative incidences of immunostained vessels were compared between the two study groups. Total vessel lengths were measured by stereological techniques.

RESULTS

The adherens junctional molecules, vascular-endothelial cadherin and beta-catenin, and the tight junctional molecules, occludin and zonula occludens-1 were localised to paracellular clefts in both study groups. The diabetic placentae showed pronounced reductions in the intensity of immunofluorescence and in the number of immuno-positive vessels. A corresponding statistically significant increase (from 19% to 56%) in the percentage of vessels showing junctional anti-phosphotyrosine immunoreactivity was found. The differences observed represented real changes in the absolute lengths of immunostained regions along the vessels. The stereological measurements failed to detect any statistically significant change in the combined length of fetal vessels in gestational diabetic placenta.

CONCLUSION/INTERPRETATION

Our results suggest that even short duration diabetic insult, alters the surface expression of placental junctional proteins. This alteration could be mediated by the tyrosine-phosphorylation pathway. The changes suggest impaired barrier function rather than accelerated vascular growth.

The fetal electrocardiogram: relationship with acidemia at delivery

OBJECTIVE

This study was undertaken to analyze the relationship between the fetal electrocardiogram and arterial pH and base excess at delivery.

STUDY DESIGN

In the labor wards of three teaching hospitals a retrospective observational study was conducted on fetal monitor recordings of 679 women for whom there was an indication for continuous fetal monitoring during labor. These women had been recruited as part of either observational studies or a prospective randomized trial related to the Nottingham fetal electrocardiographic project. Fetal heart and uterine contraction data were obtained with the Nottingham fetal electrocardiographic analyzer. Morphologic and time interval analyses of the fetal electrocardiogram were performed. Evaluation was carried out for the last half hour before delivery. Main outcome measures were umbilical arterial pH and base excess at delivery.

RESULTS

The study demonstrated a relationship between time interval analysis of the fetal electrocardiogram and a low umbilical arterial pH and base excess at delivery. Analysis of the morphologic characteristics of the fetal electrocardiogram (ST segment and T-wave height) showed no significant relationship.

CONCLUSIONS

Time interval analysis of the fetal electrocardiogram during labor is related to relative acidemia at delivery.

Effect of fetal magnetic resonance imaging on fetal heart rate patterns

OBJECTIVE

Our aim was to record the fetal heart rate before and during magnetic resonance imaging to observe the effects of the magnetic resonance imaging process on fetal heart rate parameters during imaging.

STUDY DESIGN

Fetal heart rate recordings were obtained in 10 pregnant volunteers at the time of magnetic resonance imaging. All the pregnant women were at term (37-41 weeks) with singleton fetuses in the cephalic presentation. The scanning was performed on a 0.5-T purpose-built superconductive magnet by use of echo-planar imaging. The fetal heart recordings were obtained with a modified Sonicaid Meridian 800 (Oxford) Doppler ultrasound monitor. Recordings of the fetal heart were made for a period of at least 15 minutes outside the magnet and then for at least 15 minutes inside the magnet.

RESULTS

There were no significant changes in any fetal heart rate parameters before and during the magnetic resonance imaging, as determined by the Wilcoxon matched-pairs signed-ranks test (P >.3).

CONCLUSION

This is the first report of fetal heart rate recording during magnetic resonance imaging of the fetus. Magnetic resonance imaging does not produce demonstrable effects on fetal heart rate patterns.

Cardiotocography only versus cardiotocography plus PR-interval analysis in intrapartum surveillance: a randomised, multicentre trial. FECG Study Group

BACKGROUND

There is a need to improve the sensitivity and specificity of fetal monitoring during labour. We compared the gold standard, cardiotocography, with cardiotocography plus time-interval analysis of the fetal electrocardiogram in fetal surveillance. The aim was to find out whether time-interval analysis decreased the need for operative intervention due to fetal distress.

METHODS

We did a randomised, prospective trial in five hospitals in the UK, Hong Kong, the Netherlands, and Singapore. 1038 women undergoing high-risk labours were randomly assigned fetal monitoring by cardiotocography alone, or cardiotocography plus fetal electrocardiography (ECG). Outcomes measured were rates of operative intervention, and neonatal outcome. Analysis was by intention to treat.

FINDINGS

515 women were assigned management by cardiotocography, and 523 cardiotocography plus fetal ECG. There was a trend towards fewer operative interventions for presumed fetal distress in the time-interval analysis plus cardiotocography group (63 [13%] vs 78 [16%]), but this was not significant (relative risk 0.80 [95% CI 0.59-1.08], p=0.17). There was no significant difference between groups in the proportion of babies who had an umbilical arterial pH of 7.15 or less (51 [11%] vs 49 [11%]; 1.01 [0.7-1.47]), or in the frequency of unsuspected acidaemia (42 [9%] vs 35 [8%]; 1.17 [0.76-1.79]).

INTERPRETATION

The addition of time-interval analysis of the fetal electrocardiogram during labour did not show a significant benefit in decreasing operative intervention. There was no significant difference in neonatal outcome.

Improving intrapartum surveillance: an individualised T/QRS ratio?

OBJECTIVES

To test the T/QRS ratio of the fetal electrocardiogram for normal distribution and assess the potential value of an individualised T/QRS ratio threshold to depict abnormality in the detection of fetal compromise during labour.

STUDY DESIGN

A retrospective analysis of twenty intrapartum fetal electrocardiogram recordings obtained on the labour ward of the Queen's Medical Centre, Nottingham.

RESULTS

In two of the twenty cases the T/QRS ratio was normally distributed. An increase in the T/QRS ratio over the 97.5th and 99.5th centile for 2 consecutive minutes, calculated on an individual basis, would appear to discriminate best between biochemically compromised and non-compromised fetuses. In no case was the T/QRS ratio seen to exceed 0.25 for periods previously described to be related to poor outcome.

CONCLUSION

T/QRS ratio changes with individually calculated criteria for abnormality may be of benefit in the detection of fetal compromise but the effect on the intervention rate remains to be established. The use of an absolute threshold for T/QRS ratio abnormality which is based on the assumption of a normal distribution needs to be viewed with caution.

A comparison of fetal behaviour in breech and cephalic presentations at term

OBJECTIVE

To evaluate fetal behaviour in breech and cephalic fetuses at term, using a computerised fetal behaviour program.

DESIGN

An observational study.

SETTING

Pregnancy Assessment Centre, University Hospital, Nottingham.

SAMPLE

Twenty-six breech and 58 cephalic fetuses between 36 and 41 weeks.

METHODS

Behaviour (fetal heart rate and activity) was recorded with the use of Doppler ultrasound. The duration of recording was 60 minutes or more in all but four recordings (minimum 49 minutes).

MAIN OUTCOME MEASURES

Behavioural criteria studied were 1. the relative percentage time spent in low and high variation fetal heart rate patterns; 2. the duration and recurrence of fetal activity; 3. the number of accelerations in low and high fetal heart rate variation; and 4. the number of fetal behavioural state transitions.

RESULTS

Breech fetuses differed from the cephalic group in that they were lighter than the cephalic fetuses (median 3105 g vs 3400 g; P < 0.01) and were born to older mothers (median maternal age 30 years vs 28 years; P < 0.01). No significant differences were found in rates of movement, numbers of accelerations and time exhibiting low and high fetal heart rate variation. However, breech fetuses exhibited significantly more state transitions (median 5.2/h vs 3.69/h; P = 0.01).

CONCLUSIONS

This study shows that breech fetuses are neurologically different from their cephalic counterparts in otherwise healthy pregnancies, and that subtle behavioural differences can be demonstrated in utero using this computerised method.

Computerised analysis of behaviour in normal and growth-retarded fetuses

Fetal behaviour [fetal heart rate (FHR) variation and movements (FA)] was studied in 27 normally grown fetuses and in 18 fetuses with intrauterine growth restriction (IUGR). FHR and FA were recorded using a single 1.5 MHz ultrasound transducer and analyzed by computer. The IUGR fetuses had significantly lower FA rates than the normally grown fetuses at all gestation times. They also spent a significantly lower proportion of time exhibiting high FHR variation at 28-31 weeks. Only two of the eighteen IUGR fetuses had abnormal biophysical profile scores (BPS) at the time of recording and yet all but one of them had either FHR or FA patterns that were outside the 10-90th centile range for the normally grown fetuses, suggesting that FHR and FA abnormalities predated BPS changes. More of the IUGR fetuses had abnormalities of FA than FHR. Finally, within the IUGR fetuses, those with small head circumferences (less than 3rd centile) had lower FA rates during periods of both low and high FHR variation, though this was only statistically significant for periods of low FHR variation (P < 0.05). This preliminary study offers the possibility that such objective evaluation of fetal behaviour could be used in a clinical setting and provide a more sensitive method of fetal assessment than the BPS.

Computerised analysis of fetal behaviour

Conventional analysis of fetal behaviour is laborious and time-consuming. For it to have a role in a clinical setting, practical and more objective methods are necessary. We describe a computerised fetal behavioural analysis programme. Fetal behaviour (in the form of heart rate and movement) was recorded using a conventional Doppler ultrasound transducer. Data are presented comparing the method with conventional forms of behavioural analysis and documenting its limitations.

Computerized analysis of behavior in fetuses with congenital abnormalities

An observational study was undertaken to evaluate a computerized fetal behavior program in a clinical setting. Behavior of normal fetuses was compared with that of fetuses with a variety of congenital abnormalities. Forty-three fetuses were studied at 28-36 weeks; 26 were normal (49 recordings) and 16 had congenital abnormalities (26 recordings; ten had structural abnormalities of the central nervous system, one had Down's syndrome and five had other abnormalities). Behavior was recorded with the use of Doppler ultrasound. The duration of each recording was 60 min or more in all but two instances. The behavioral criteria studied were (1) the relative percentage of time spent in low and high fetal heart rate (FHR) variation; and (2) the percentage of time fetal activity was detected in low and high FHR variation. Fetuses with abnormalities exhibited varying patterns of behavior: only eight had patterns of FHR variation that were within the 10th and 90th centiles for normal fetuses and only one fetus exhibited a fetal activity pattern that was between the 10th and 90th centiles for the normal group. All the abnormal fetuses had a FHR pattern and/or fetal activity rate outside the 10th or 90th centiles. This study suggests that such a computerized behavioral analysis program may serve as a functional adjunct to the evaluation of a fetus with structural abnormalities.

Antenatal genetic counselling: implications for population screening

Only 1-2% of newborns have a congenital abnormality, yet it is responsible for the much greater proportion of mortality and morbidity in infancy and in childhood as well as during pregnancy. Because of this prevalence, there have been many developments in screening and diagnosis of congenital abnormality. Yet there are a number of limitations about how the screening and diagnostic service is currently operated. These limitations centre on the information that is provided, who undertakes the counselling, and their training and support provided to parents in making important decisions.

Changes in the PR interval--fetal heart rate relationship of the electrocardiogram during fetal compromise in chronically instrumented sheep

OBJECTIVES

The evaluation of the changes in the relationship of the PR interval and fetal heart rate during prolonged fetal compromise in sheep at levels of acidosis comparable to those seen during human fetal compromise and to see whether these changes are potentially of use in the detection of fetal distress.

STUDY DESIGN

A retrospective analysis of continuous fetal electrocardiogram recordings during graded fetal hypoxemia in 20 chronically cannulated fetal sheep was performed. Baseline recordings during normoxemia were compared with recordings during hypoxemia by use of Fisher's exact test and the Student t test.

RESULTS

Sixteen of the 20 cases could be used for final analysis. Twelve showed a statistically significant change from a predominantly negative relationship between the PR interval and the fetal heart rate during normoxemia to a predominantly positive relationship during hypoxemia. Two cases showed an obvious trend in the same direction, which was statistically not significant. In two other cases no change in the relationship was observed.

CONCLUSION

A changing relation between the PR interval and the fetal heart rate is of potential use in the detection of fetal compromise.

The potential impact of PR interval analysis of the fetal electrocardiogram (FECG) on intrapartum fetal monitoring

A retrospective study was performed at the Queens Medical Centre, Nottingham, UK to evaluate the potential value of PR interval analysis of the FECG compared to conventional intrapartum assessment with fetal heart rate monitoring. Two-hundred sixty-five labours were selected for monitoring. Outcome was assessed by the number of fetal scalp blood samples (FBS) performed and the associated incidence of acidosis in the first stage of labour, the mode of delivery and whether or not this was expedited for fetal heart abnormality or an abnormal scalp pH. The condition of the fetus at delivery was assessed by arterial and venous blood acid-base status, Apgar score and the need for admission to the neonatal intensive care unit. Conventional electronic fetal heart rate monitoring (EFM) was used in all labours. The addition of PR interval assessment would potentially reduce the numbers of normal FBSs being carried out from 85.5% to 26.8% and the proportion of cases of missed acidosis at delivery from 8.5% to 4.5%. These results highlight the potential benefit of PR interval analysis in improving interpretation of the intrapartum cardiotocograph and need to be tested by prospective randomised controlled study.

The fetal electrocardiogram

Advances in microprocessing technology have made fetal ECG analysis a feasible adjunct to fetal surveillance. Time interval and morphology changes of the FECG occur during fetal hypoxia. The use of these changes to detect a fetus at risk of intrapartum asphyxia awaits validation in terms of both future and ongoing clinical trials. Recognition of FECG changes during decelerations may improve the sensitivity of EFM. Antepartum FECG analysis has potential for the detection of a number of pathological fetal conditions, including intrauterine growth retardation, but remains hampered by low signal-to-noise ratios, rendering successful signal acquisition unreliable.

Improved intrapartum surveillance with PR interval analysis of the fetal electrocardiogram: a randomized trial showing a reduction in fetal blood sampling

OBJECTIVE

Our goal was to test the hypothesis that the addition of fetal electrocardiogram time-interval analysis to conventional electronic fetal monitoring would significantly reduce the number of cases requiring fetal scalp blood sampling without an increase in adverse outcome.

STUDY DESIGN

A randomized prospective trial was performed in 214 women with high-risk labor.

RESULTS

There was a significant reduction in the number of cases that had fetal blood sampling performed in the fetal electrocardiogram plus electronic fetal monitoring group (risk ratio for electronic fetal monitoring alone 3.53; p < 0.01, 95% confidence interval 1.39 to 8.95). The fetal blood samplings performed in the electronic fetal monitoring alone group were less likely to be abnormal (pH < 7.25, base excess < -8.0) than those performed in the fetal electrocardiogram plus electronic fetal monitoring group (risk ratio for electronic fetal monitoring alone 0.62, p = 0.05, 95% confidence interval 0.35 to 1.10). There was a trend of more infants with an arterial umbilical pH < 7.15 and a base excess less than -8.0 mmol/L at birth being unsuspected and more instrumental deliveries for presumed fetal distress being performed in the electronic fetal monitoring alone than in the fetal electrocardiogram plus electronic fetal monitoring group.

CONCLUSION

The addition of fetal electrocardiogram analysis to conventional electronic fetal monitoring during labor can reduce significantly the number of parturients undergoing fetal scalp blood sampling and can simultaneously increase its efficiency without an increase in adverse outcome.

Computerised fetal heart rate analysis in labour--effect of sampling rate

OBJECTIVE

To study the effect of sampling rate on the accuracy of fetal heart rate recording in labour.

DESIGN

Prospective observational study.

METHODS AND SUBJECTS

The fetal heart rate was obtained from 153 fetuses in labour. The heart rate data was sampled at a rate of 0.5 Hz (every 2 s) and the means and standard deviations of 5-min segments compared against the mean and standard deviation for all beats in the same time interval.

RESULTS

There was a highly significant correlation between the means (r = 0.994, p < 0.001) and standard deviations (r = 0.957, p < 0.001) of FHR sampled on successive beats compared with 2 s sampling.

CONCLUSION

Two second sampling of the fetal heart rate in labour will allow a highly complex analytical algorithm to process the signal in near real time for objective analysis.

Atrioventricular block during fetal heart rate decelerations

Electrocardiograms (ECG) was examined in 15 fetuses during fetal heart rate decelerations in labour. Sinus bradycardia was demonstrated in six cases and in two cases inversion of the P wave was seen. In seven cases there was complete dissociation of the P wave from the QRS complex, indicating complete atrioventricular heart block. Many decelerations are vagally mediated, but such cases associated with complete atrioventricular heart block may be due to the effect of hypoxia on the bundle of His.

Cumulative changes in the fetal electrocardiogram and biochemical indices of fetal hypoxia

Previous studies have shown that the relationship between P-R interval of the fetal electrocardiogram (FECG) and the fetal heart rate (FHR) varies according to the acid-base status of the fetus. In the normal fetus there is a negative correlation between these two parameters. However, as acidosis develops, the relationship becomes positive. In order to express this relationship in a quantitative form, an index known as the ratio index (RI) has been derived. This index provides a cumulative time based description of the relationship between the P-R interval and FHR for the whole labour. The aim of this study was to evaluate this derived index and compare it with fetal hypoxia. The FECG was recorded from 132 fetuses during labour using a fetal scalp electrode, and analysed using the Nottingham FECG system. Changes in the nature of this relationship between the P-R interval and heart rate were compared against biochemical markers of asphyxia, namely umbilical artery pH, lactate and umbilical venous norepinephrine and hypoxanthine. Significant correlations were demonstrated between the RI and umbilical arterial pH (r = -0.38, P < 0.01), lactate (r = 0.36, P < 0.01), log10norepinephrine (r = 0.37, P < 0.01), and hypoxanthine (r = 0.28, P < 0.01). The measurement of the ratio index during labour may be a useful method of determining fetal hypoxia during labour.

Amniotic fluid zinc and pregnancy outcome

OBJECTIVE

To examine for an association between amniotic fluid zinc and pregnancy outcome.

DESIGN

A prospective study.

SETTING

Southmead Hospital, Bristol, UK.

SUBJECTS

191 amniotic fluid samples from 11 centers in the Southwest of England, obtained at 16-20 weeks gestation.

METHOD

Samples of amniotic fluid (AF) sent for prenatal diagnosis were collected from the laboratory and analysed for zinc level. Data were then collected at a later date concerning pregnancy outcome.

OUTCOME MEASURE

Antenatal complications as well as events in labour, and in particular birth weight and congenital malformations.

RESULTS

182 cases with complete data showed a mean AF zinc level (+/- S.E.) of 1.39 (+/- 0.11). There was no relation between AF zinc and antepartum haemorrhage, pregnancy-induced hypertension, post-partum haemorrhage or time and mode of delivery. Neither was there an association with birth weight. As there were no cases with major malformations, particularly of the central nervous system, possible association could not be ascertained.

CONCLUSION

The study failed to demonstrate any association between AF zinc and abnormal pregnancy outcome. A modified prospective study is suggested to explore this further.

Reagent strip testing of antenatal urine specimens for infection

OBJECTIVE

To compare reagent strip testing (RST) with microscopy and culture in identifying significant bacteriuria, and secondly, to consider potential cost savings if RST screening proved to be reliable.

DESIGN

Prospective descriptive study.

SETTING

Antenatal Clinic, Bristol Maternity Hospital.

SUBJECTS

Eight hundred and ninety-eight women having urine testing in pregnancy for microscopy and culture either routinely or because of a clinical infection.

INTERVENTIONS

The midstream specimens of urine had RST examination using Ames Multistix 8SG prior to being sent to the laboratory.

MAIN OUTCOME MEASURE

Significant culture (> 10(5) colonies/ml) of a single organism in culture.

RESULTS

The highest predictive value for a negative result of the urine culture (99.7%) was obtained when using four RSTs in combination. The RST for nitrite had a high predictive value for a positive urine culture (90%). The samples which gave a false negative result with RST screening were mainly infected with low grade urinary pathogens or genital tract contaminants.

CONCLUSION

RST screening for bacteriuria provides a reliable and cheap alternative to culture of all urine specimens.

Gastro-intestinal crises during pregnancy

In general pregnancy is not associated with an increase in the incidence of gastro-intestinal (GI) conditions, but it is associated with an increase in the severity of these conditions. This is largely due to a delay in making the diagnosis. Delay is caused by a combination of factors. These include mimicry of symptoms and signs with pregnancy-related conditions, a change in the usual clinical presentation, reluctance to use radiological diagnostic aids and a higher threshold for performing invasive investigative procedures. However before resorting to invasive investigations, it is imperative that appropriate non-invasive investigations are performed and evaluated first. This is especially relevant to liver conditions in pregnancy which can present with abdominal pain. Optimal management of GI conditions in pregnancy requires both surgeons and obstetricians to be aware of the problems of diagnosis, communicate promptly and investigate without delay in order to make a diagnosis and avert a GI crisis. This article discusses the clinical presentation, diagnosis and management of the common GI conditions occurring in pregnancy.

Pre-eclampsia and trisomy 13

OBJECTIVE

To assess the reported association between field trisomy 13 and maternal pre-eclampsia.

DESIGN

A retrospective case-control study.

SUBJECTS

Twenty-five women who gave birth to trisomy 13 infants in southwest England between 1971 and 1989; 38 women who gave birth to trisomy 18 infants in the same region over the same time and 50 women with normal karyotype infants matched for age, parity, and date of delivery with the trisomy 13 group.

MAIN OUTCOME MEASURES

The medical records of all the women in the three groups were analysed for evidence of pre-eclampsia. Four different thresholds of pre-eclampsia were used. The incidence of pre-eclampsia was compared between the three study groups and analysed separately for primigravid and multigravid women.

RESULTS

The incidence of pre-eclampsia in pregnancies complicated by trisomy 13 was significantly higher than the incidence in the trisomy 18 and the normal karyotype control groups. This association was more pronounced in primigravid pregnancies.

CONCLUSIONS

This, the largest survey of trisomy 13 and pre-eclampsia to date, suggests an association between the two conditions. It also supports the argument for a fetal factor in the pathogenesis of pre-eclampsia. We speculate on how genes encoded on chromosome 13 may be responsible.

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.

Management of severe pre-eclampsia and eclampsia by UK consultants

OBJECTIVE

To determine the current management of severe pre-eclampsia and eclampsia in the United Kingdom.

DESIGN

One-page postal survey to all (1007) UK consultant obstetricians with questions about use of antihypertensive and anticonvulsant drugs in severe pre-eclampsia and eclampsia, other management strategies, definition of factors determining severity, protocol development and regional review.

RESULTS

688 replies (69.6% response rate). The antihypertensive drugs used were mainly oral labetalol (35%), oral methyl dopa (23%) and parenteral hydralazine (29%); diuretics were not used. Diazepam was the preferred drug in eclampsia. Very few consultants used magnesium sulphate (2%). Anticonvulsants were also prescribed by 85% of consultants to prevent fits; the drugs then preferred were diazepam (41%), phenytoin (30%) and chlormethiazole (24%). Two-thirds of consultants felt there was a need for trials to study the effectiveness of antihypertensive and anticonvulsant drugs. In a woman with proteinuric hypertension, 15% of consultants did not regard the development of headache as indicating severe pre-eclampsia. Consistent management practices were not associated with agreement about protocols. Regional review does not appear to have occurred.

CONCLUSION

Antihypertensive and anticonvulsant therapies are widely used but trials are considered necessary. Improvements in the management of women with severe pre-eclampsia or eclampsia might occur if UK obstetricians sought more collective opinion and undertook regional audit of protocols.

Comprehensive fetal assessment with three ultrasonographic characteristics

OBJECTIVES

When three ultrasonographic characteristics--umbilical artery Doppler recording, growth (abdominal circumference), and biophysical profile score--are used in combination in assessment of fetuses at risk of chronic asphyxia: (1) What are the order and time scale for the development of abnormality with each characteristic? (2) What is the short-term outcome associated with abnormalities of the three characteristics? (3) Should we amend our fetal assessment protocol?

STUDY DESIGN

An audit of 103 fetuses (100 mothers) referred to a tertiary center for fetal assessment because of suspected chronic fetal asphyxia was performed with three ultrasonographic characteristics, umbilical artery Doppler recording, measurement of abdominal circumference, and documenting the biophysical profile score.

RESULTS

The order of deterioration (which had a very variable time scale) was umbilical artery Doppler recording, followed by abdominal circumference and finally biophysical profile score. Normal characteristics or an abnormal umbilical artery Doppler recording alone or an abnormal abdominal circumference alone was associated with an excellent prognosis. The worst outcome was found in the 28 fetuses with abnormality of all three ultrasonographic features before delivery.

CONCLUSIONS

The main suggested implications for management are avoidance of preterm delivery with normal ultrasonographic characteristics, an abnormal umbilical artery Doppler recording alone, or an abnormal abdominal circumference alone; delivery of fetuses at greater than or equal to 34 weeks with abnormal umbilical artery Doppler recording and abdominal circumference before the biophysical profile score becomes abnormal; and implementation of specific measures to prevent necrotizing enterocolitis in newborns when all three characteristics are abnormal.