The effects of maternal betamethasone administration on the fetus

The effects of antenatal betamethasone administration on fetal heart rate and behaviour depend on gestational age

OBJECTIVE

We previously reported decreases in fetal heart rate (FHR) variability and body and breathing movements after maternal betamethasone administration. We now test the hypothesis that fetal responsiveness to betamethasone depends on the gestational age at which glucocorticoid therapy is started.

DESIGN OF THE STUDY

1-h recordings of FHR (n=350) and fetal movements (n=310) made during a 5-day period (days 0-4) were available for analysis. The recordings had been obtained from 63 pregnant women at high risk for preterm delivery who received betamethasone (two doses of 12 mg 24 h apart) between 26 and 34 weeks' gestational age (wGA). The response to betamethasone, i.e. the direction and magnitude of change in FHR and movement parameters compared with baseline (day 0), was studied in relation to gestational age at drug administration.

RESULTS

Fetuses exposed to betamethasone at 29-34 wGA showed a decrease in FHR on day 1 (indicative of baroreceptor reflex), and reduced breathing activity and prolonged episodes of quiescence with a concomitant decrease in body movements on days 1 and 2. However, these changes were not observed if betamethasone administration occurred at 26-28 wGA. Betamethasone-induced reductions in FHR variability were similar in young and older fetuses.

CONCLUSIONS

Age-related differential responsiveness to betamethasone was found for all studied fetal processes (body and breathing movements, FHR, and quiescence), except FHR variability. Our results suggest ontogenic changes in the mechanisms presumed to underlie these processes (glucocorticoid receptor (GR) maturation, cardiovascular and neuro-endocrine development).

Immediate and delayed effects of antenatal corticosteroids on fetal heart rate: a randomized trial that compares betamethasone acetate and phosphate, betamethasone phosphate, and dexamethasone

OBJECTIVE

The purpose of this study was to evaluate the role of different formulations and different administration kinetics of antenatal corticosteroid therapy on fetal heart rate.

STUDY DESIGN

One hundred five patients who were at high risk for preterm delivery were assigned randomly to receive two injections of betamethasone acetate + phosphate, four injections of betamethasone phosphate, or four injections of dexamethasone phosphate. Computerized fetal heart rate was recorded daily through day 4.

RESULTS

The three formulations did not differ in their effect on fetal heart rate, which varied significantly as a function of the time of injection. During treatment (day 0-day 1), fetal heart rate variability increased (+9%, P <.05), as did the number of fetal movements felt by the mother (+60% at day 0, P <.001). After treatment (day 2-day 3), variability fell significantly (-14%, P <.01), as did accelerations (-35% at day 2, P <.01). No modifications were still detectable on day 4.

CONCLUSION

Antenatal corticotherapy is responsible for two different phases of fetal heart rate modifications that do not vary according to the corticosteroid or the dosage regimen.

Cardiovascular fluctuations and transfer function analysis in stable preterm infants

To examine the baroreceptor reflex function, a beat-to-beat analysis between systolic blood pressure (SBP) and R-R interval fluctuations was studied in 10 stable appropriate-for-gestational age preterm infants (range, 27.2-33.7 wk) in the first postnatal week during quiet sleep. Spectral power analysis, using fast Fourier transform, and transfer functions (gain and phase difference) between SBP and R-R fluctuations were estimated in a low-frequency band (LF, 0.03-0.2 Hz) and high-frequency band (HF defined as the frequency band between the 10th and 90th centiles of the individual respiratory frequency). The LF/HF ratio reflects the sympathovagal balance. The mean frequency (+/-SD) of LF peaks was centered at 0.07 +/- 0.02 Hz. The mean frequency (+/-SD) of the individual HF band was 0.82 +/- 0.21 Hz. The LF/HF ratio in the R-R interval series [median, 29; interquartile range (IQR), 16-40] was higher than in the SBP series (median, 8; IQR, 4-14). The gain between R-R interval and SBP fluctuations (median, 4.2 ms/mm Hg; IQR, 2.4-5.0) in the LF band was higher than in the HF band (median, 1.7 ms/mm Hg; IQR, 1.4-3.0). SBP fluctuations lead R-R interval fluctuations in the LF band with a median phase difference of +96 degrees (IQR, 67-132). At LF the fluctuations in SBP precede changes in R-R interval with a time delay of 3.8 s. These observations indicate a dominant role of the sympathetic system in stable preterm infants in comparison with published adult values. Cross-spectral analysis allows a test for tracking the development of the sympathetic system in neonates.

The effect of glucocorticosteroid administration on fetal movements and biophysical profile scores in normal pregnancies

OBJECTIVE

To evaluate and quantify the effect of glucocorticosteroid administration on fetal movements and biophysical profile scores.

METHODS

Eighteen women at 32-34 weeks' gestation were enrolled. Inclusion criterion was an uncomplicated singleton pregnancy not considered to be at high risk. Patients participated for 3 consecutive days. On day 1, the patients underwent a baseline biophysical profile including a non-stress test followed by a 12-mg betamethasone intramuscular injection. On day 2, the patients received a non-stress test and a second dose of betamethasone. On day 3, a biophysical profile with non-stress test was performed. Maternal counts of fetal kicks were also recorded before, during and after the study period. Each test was conducted at approximately the same time of day to control for diurnal variation. Comparison was made between pre-betamethasone biophysical profile scores and fetal movement and post-betamethasone biophysical profile scores and fetal movement.

RESULTS

Biophysical profile scores were reduced in 28% of the study population after betamethasone administration (p < 0.05). Amniotic fluid index on day 3 was decreased from baseline in 72% of patients after betamethasone administration (p < 0.05). Forty-four per cent of patients reported a decrease in fetal movement. Of these patients, 87% had a decreased amniotic fluid index when compared to baseline (p < 0.05).

CONCLUSIONS

Fetal movements and breathing motion were decreased after glucocorticosteroid administration, as evidenced by biophysical profile scores and kick counts. The decrease in the amniotic fluid index observed after glucocorticosteroid administration may have been the result of decreased fetal breathing and, therefore, decreased efflux of alveolar fluid into the amniotic sac.

Three-dimensional power Doppler in study of embryonic vasculogenesis

Three-dimensional power Doppler sonography plays an important role in obstetrics, predominantly for assessing the relationship between fetal vascular system and surrounding organs. Presenting volume data in a standard anatomic orientation is valuable for assisting both ultrasonographers and pregnant patients to recognize anatomy more readily. This investigation was designed as an observational cross-sectional study. A group of 25 patients in gestational age of five to eleven weeks were recruited for the study. Architecture of the embryonic vessels was depicted by 3D power flow mapping and analyzed visually. Vascular 3D measurements were done through 3D color/power histogram and expressed by Vascularization Index (VI) and Vascularization Flow Index (VFI). Volume of the embryo increased exponentially throughout the observation period. The VI and VFI showed no change despite an exponential growth of embryonic volume. The findings of our study suggest that in cases of physiologic embryonic vasculogenesis there is a homeostatic steady state between tissue demands and blood supply given through the vascular network.

Three-dimensional sonoembryology

Three-dimensional (3D) ultrasound plays an important role in obstetrics, predominantly for assessing fetal anatomy. Presenting volume data in a standard anatomic orientation valuably assists both ultrasonographers and pregnant patients to recognize the anatomy more readily. Three-dimensional ultrasound is advantageous in studying normal embryonic and/or fetal development, as well as providing information for families at risk for specific congenital anomalies by confirming normality. This method offers advantages in assessing the embryo in the first trimester due to its ability to obtain multiplanar images through endovaginal volume acquisition. Rotation allows the systematic review of anatomic structures and early detection of fetal anomalies. Three-dimensional ultrasound imaging in vivo compliments pathologic and histologic evaluation of the developing embryo, giving rise to a new term: 3D sonoembryology. Rapid technological development will allow real-time 3D ultrasound to provide improved and expanded patient care on the one side, and increased knowledge of developmental anatomy on the other.

Corticosteroids and fetal vasculature: effects of hydrocortisone, dexamethasone and betamethasone on human umbilical artery

OBJECTIVE

To investigate the direct effects of corticosteroids on human umbilical artery resistance, in vitro.

DESIGN

Prospective laboratory study.

SETTING

University teaching hospital.

SAMPLES AND METHODS

Umbilical artery samples were obtained following normal, term deliveries (n = 50) and dissected rings were suspended for isometric recording under physiological conditions. The effects of hydrocortisone (10(-9) - 10(-4) M), dexamethasone (10(-9) - 10(-4) M) and betamethasone (10(-9) - 10(-4) M) on umbilical artery resistance were measured in vitro.

MAIN OUTCOME MEASURES

Changes in umbilical artery resistance, in vitro.

RESULTS

Hydrocortisone (n = 12) exerted a vasodilatory effect on human umbilical artery at all concentrations studied compared with vehicle control experiments (n = 12) (P < 0.0001). The mean net relaxant effect of hydrocortisone ranged from 11.77% (10(-9) M) to 57.01% (10(-4)). Both exogenous compounds, dexamethasone (n = 12) and betamethasone (n = 12), similarly exerted a significant relaxant effect on human umbilical artery tone (P < 0.05-0.01), compared with vehicle control experiments (n = 12). The mean net relaxant effect of dexamethasone ranged from 14.43% (10(-9) M) to 38.12% (10(-4)) and that of betamethasone ranged from 6.02% (10(-9) M) to 42.30% (10(-4)), in a cumulatively increasing fashion. There was a non-significant trend towards a greater vasodilatory effect of dexamethasone than betamethasone at lower bath concentrations studied.

CONCLUSION

Corticosteroids exert a direct and potent vasodilatory effect on human umbilical artery resistance in vitro, thus providing an explanation for the previously unexplained vascular effects associated with antenatal administration of corticosteroids.

Steroid use during pregnancy

Health care providers and pregnant women share a concern for protecting the fetus from unnecessary and potentially teratogenic influences. Since the introduction of steroids for the induction of fetal surfactant production, there has been considerable experience in the use of corticosteroids during pregnancy. While the use of corticosteroids for surfactant induction in the preterm fetus has become commonplace, steroids are used for other obstetric and medical indications during pregnancy. Thus, finding a balance between drug benefits and possible side effects remains a critical issue.

The effect of steroids on the biophysical profile and Doppler indices of umbilical and middle cerebral arteries in healthy preterm fetuses

OBJECTIVE

To examine the effect of antenatal steroids on the biophysical profile and the Doppler parameters of umbilical and middle cerebral arteries of healthy fetuses.

STUDY DESIGN

Thiry-five singleton pregnancies between the gestational ages of 28 and 34 weeks, who received two consecutive doses of betamethasone 24h apart to accelerate pulmonary maturation were prospectively studied. Fetal biophysical profile and Doppler assessment were performed at 0 (pre-steroid), 24, 48, 72, 96 and 120 h after the administration of first dose. We compared the percentage of the fetuses with biophysical parameters present for each of the five components of the biophysical profile and the Doppler indices, using Cochran's Q-test, Friedman's test and one way analysis of variance of repeated measures where appropriate. The statistical significance was defined as P<0.05.

RESULTS

The mean delivery time was 36.9(+/-1.8) weeks. There was a statistically significant difference in the frequency of the following findings in the pre- compared to post-steroid measurements: absence of body movements (48 h, P<0.05), non-reassuring fetal heart rate tracings (24, 48 and 72 h, P<0.05) and absence of breathing movements (24, 48 and 72 h, p<0.05). Initially none of the biophysical profile score was <or=6, whereas at 24, 48 and 72 h, 13.3, 76.7, 16.7% of them, respectively, were <or=6 (P<0.05). None of the Doppler indices was found to be affected by the steroid administration.

CONCLUSION

Maternal betamethasone administration can cause a significant but transient, reduction in biophysical profile scores, however the middle cerebral and umbilical artery Doppler indices were found to be unaffected suggesting the reliability of this modality for the evaluation of the fetuses previously exposed to the antenatal steroids.

Prenatal influences on neuroimmune set points in infancy

Many factors during fetal life and early infancy have been found to affect the development of immune responses in animals. This study investigated whether acute exposure of the fetal monkey to high levels of corticosteroids would also have a lingering effect on the expression of immune responses still manifest postpartum in yearling juveniles. One month prior to parturition, pregnant rhesus monkeys were administered dexamethasone for two days. Lymphocyte proliferative responses to mitogen were then examined in their offspring when they were between 1.0-1.5 years of age. In addition, cell sensitivity to corticosteroid feedback was assessed by testing the ability of a gradation of cortisol doses to inhibit proliferation. Monkeys generated from dexamethasone-treated pregnancies tended to have lower responses to concanavalin A. Further, their cells were less sensitive to in vitro incubation with cortisol, suggesting that elevated adrenal activity in vivo had downregulated hormone receptors on their cells. These findings concur with the view that steroidal hormones in utero can influence the fetal immune system, resulting in prolonged effects on immune responses after birth. The similarity of the dexamethasone condition to the clinical treatment used in obstetrical practice raises a potential concern about the widespread antenatal exposure of premature infants to steroidal drugs.

Effect of antenatal betamethasone therapy on maternal-fetal Doppler velocimetry

BACKGROUND

The effect of antenatal betamethasone on fetal parameters includes a transient reduction of FHR variation and of fetal body movements. An effect on maternal-fetal blood flow has also been shown, with non-univocal results.

AIMS

To evaluate the effect of antenatal betamethasone in third trimester singleton high-risk pregnancies by Doppler technology.

SUBJECTS AND METHODS

Thirty-six pregnant women who received a full course of betamethasone (12 mg i.m. two times, 24 h apart) were studied. The Doppler examination included the assessment of the pulsatility index (PI) of the umbilical artery (UA PI), the middle cerebral artery (MCA PI) and of resistance index of uterine arteries (Ut RI) before treatment, and 48 and 96 h after second dose of betamethasone.

RESULTS

No significant variation was noted in UA PI through betamethasone therapy. MCA PI decreased significantly 48 h from the last injection of betamethasone (P=0.002), and returned to basal values at 96 h. No difference was found for the other Doppler parameters examined. When serial Doppler studies were analyzed according to the gestational age, in the group <32 weeks' gestation, MCA PI decreased significantly after 48 h (P<0.006) and returned to pre-treatment values after 96 h from the last betamethasone dose. Conversely, no difference was found in Doppler serial measurements in any of the analyzed districts in the subgroup > or =32 weeks.

CONCLUSION

Betamethasone treatment is associated with a significant, although transient, reduction of MCA PI, especially at gestational ages <32 weeks'.

Effect of antenatal steroid administration on the fetal biophysical profile

PURPOSE

Our objective was to determine whether antenatal steroid administration affects the biophysical profile score in fetuses.

METHODS

A prospective study was conducted in 84 fetuses between 28 and 34 weeks' menstrual age at risk of preterm delivery. Two intramuscular injections of 12 mg of betamethasone were given to the mother 24 hours apart. All fetuses underwent biophysical profile testing prior to and between 24 and 48 hours after steroid administration. Biophysical profiles (including nonstress tests) were evaluated by two maternal-fetal medicine specialists blinded to the timing of steroid administration. Neonatal outcome, including Apgar score, menstrual age at delivery, admission to and length of stay in the neonatal intensive care unit, and mortality, was analyzed in all subjects.

RESULTS

In 31 (37%; 95 confidence interval, 26.6-47.2%) of 84 cases, the biophysical profile score decreased at least 2 points after steroid administration. The most commonly affected variables were fetal breathing and the nonstress test. There was no significant difference in the neonatal outcome between the fetuses whose biophysical profile decreased and those whose did not.

CONCLUSIONS

Biophysical profile scores were decreased in more than one third of fetuses within 48 hours of antenatal steroid administration, but neonatal outcome was not affected. Knowledge of this occurrence could avoid incorrect decision making regarding fetal well-being.

Effects of maternal dexamethasone administration on fetal Doppler flow velocity waveforms

OBJECTIVE

To investigate the effects of maternal dexamethasone administration on umbilical and fetal cerebral artery flow velocity waveforms.

DESIGN

Cross-sectional study.

SETTING

Department of Obstetrics and Gynaecology, Robert Ballanger Hospital, Aulnay-sous-Bois, France.

SAMPLE

Twenty-six pregnant women with singleton pregnancies considered at risk for preterm delivery. At baseline, all pregnancies had normal fetoplacental vascular resistance.

METHODS

These women were given weekly six intravenous doses of 4 mg of dexamethasone eight hours apart.

MAIN OUTCOME MEASURES

Doppler studies were performed from both umbilical artery (UA) and fetal middle cerebral artery (MCA) before (day 0), during (day 2), immediately after (day 4) and shortly after (day 7) every steroid course.

RESULTS

No significant variation was noted in both umbilical artery pulsatility index (PI) and fetal heart rate through dexamethasone therapy. Compared with mean initial values, we found on day 4 a significant decrease in MCA PI of 0.28 (F = 7.17, P < 0.001) and a significant increase in UA:MCA PI ratio of 0.08 (F = 3.85, P = 0.013); in contrast no significant change was documented on days 2 and 7 in both MCA pulsatility index and UA:MCA PI ratio. After multiple regression analysis, only the decrease in fetal middle cerebral artery pulsatility index on day 4 remained significant (F= 5.84, P= 0.001).

CONCLUSIONS

The current study finds in healthy fetuses a transient, significant and unexplained decrease in fetal middle cerebral artery impedance on the fourth day following maternal dexamethasone administration. Further basic research and clinical studies including larger sample sizes or pregnancies with fetoplacental dysfunction are needed.

The study of morphology and circulation of early embryo by three-dimensional ultrasound and power Doppler

Three-dimensional (3-D) ultrasound plays an important role in obstetrics predominantly for assessing fetal anatomy. Presenting volume data in a standard anatomic orientation assists both ultrasonographers and pregnant patients to recognize anatomy more readily. Three-dimensional ultrasound is advantageous for the study of normal embryonic and/or fetal development, as well as providing information for families at risk for specific congenital anomalies by confirming normality. This method offers advantages in assessing the embryo in the first trimester as it is able to obtain multiplanar images through endovaginal volume acquisition. Rotation of the embryo and close scrutiny of the volume allow the systematic review of anatomic structures such as cord insertion, limb buds, cerebral cavities, stomach and bladder. Using this modality one can easily obtain the volumes of the gestational sac and yolk sac and can evaluate their relationship to prediction of pregnancy outcome. Three-dimensional power Doppler sonography has the potential to study process of placentation and evaluate the development of the embryonic and fetal cardiovascular systems. Three-dimensional ultrasound imaging in vivo compliments pathologic and histologic evaluation of the developing embryo, giving rise to a new term: 3-D sonoembryology. Rapid technological development will allow real-time 3-D ultrasound to provide improved and expanded patient care on the one side, and increased knowledge of developmental anatomy on the another.

Temporal organization of fetal behavior from 24-weeks gestation onwards in normal and complicated pregnancies

Developmental aspects of behavioral organization were investigated in 29 healthy fetuses from 24-weeks gestation onwards: (a) short-term association between body (GM) and eye (EM) movements; (b) linkage of pairs of the three state variables [fetal heart rate pattern (FHRP), GM, and EM]; and (c) sequence of change of state variables during transitions. Linkage and sequence were also studied in complicated pregnancies. Short-term association between GM and EM was well established after 28 weeks. Linkage of state variables improved considerably after 32-34 weeks. FHRP was the first variable to change during synchronized transitions from 1F to 2F between 28-39 weeks, and the last variable during 2F to 1F transitions between 32-39 weeks. Although clear developmental patterns could be recognized, the interfetal variability was such that identification of the abnormal fetus is still difficult. Only transitions were significantly different in growth-restricted fetuses, as they showed no specific sequence of change. Assessing the temporal organization of fetal behavior seems, therefore, until now, not of great clinical value.

Temporal changes in fetal cardiovascular, behavioural, metabolic and endocrine responses to maternally administered dexamethasone in the late gestation fetal sheep

OBJECTIVE

To determine the primary (0-12 h) and secondary (12-24 h) effects of dexamethasone on fetal heart rate, short term heart rate variation, blood pressure, breathing movements and electrocortical activity, blood gas exchange, metabolism and adrenocortical function in the late gestation sheep fetus.

DESIGN

Comparison of the effects of a single maternally administered intramuscular injection of dexamethasone (12 mg) with those of saline vehicle from 1 h before injection to 24 h post-injection. Fetal cardiovascular and behavioural parameters were recorded continuously. Fetal and maternal blood samples were taken at regular intervals for blood gas, glucose and lactate, cortisol and adrenocorticotrophin measurements.

SAMPLE

Sixteen chronically instrumented singleton fetal sheep at 127-133 days of gestation (term is about 147 days).

RESULTS

During the primary phase short term heart rate variation fell (P < 0.001), and this was associated with a transient fall in the incidence of fetal breathing movements, a fall in fetal heart rate and a rise in fetal blood pressure. By 12 h there was a significant increase in short term heart rate variation (P < 0.001) and a rise in fetal heart rate, but blood pressure and fetal breathing movements had returned to normal. Dexamethasone significantly reduced fetal PaO2 throughout most of the experimental period, particularly 1 h post-injection (P < 0.005). Fetal and maternal plasma cortisol and adrenocorticotrophin concentrations fell significantly from 1 h post-injection.

CONCLUSIONS

The effects of dexamethasone on fetal heart rate variation are more complex than previously described with both a fall and an increase observed depending on the time at which heart rate variation was measured after injection. Dexamethasone also caused a significant fall in fetal PaO2, and although this was not to hypoxic levels in normoxic fetuses it does raise questions about the potential impact of dexamethasone on chronically hypoxic fetuses.

Altered immune function in human newborns after prenatal administration of betamethasone: enhanced natural killer cell activity and decreased T cell proliferation in cord blood

During the course of human pregnancy, glucocorticoid (GC) treatment is given when preterm delivery is expected. This treatment is successful in stimulating the development of the fetal lung. However, in animal studies, a number of side effects of perinatal GC treatment have been described. The aim of the present study was to evaluate in humans the effects of antenatal GC treatment on development of the immune system. In addition, we examined the development of immune reactivity in infants born preterm and at term who did not receive GC treatment antenatally. We tested mitogen-induced T cell proliferation, natural killer cell activity, and lipopolysaccharide-induced IL-6 production in cord blood samples. We found that there is a significant effect of gestational age on the capacity of T cells to proliferate and of natural killer cells to kill K562 tumor cells. The capacity to produce IL-6 does not change between gestational age 26 and 41 wk. Moreover, our results show that antenatal treatment with GC does have immunomodulatory effects: T cell proliferation is decreased in infants born very preterm (gestational age 26-31 wk) as well as in infants born between 32 and 36 wk of gestation. In contrast, the activity of natural killer cells is only increased in GC-treated infants born between 26 and 31 wk. We did not observe a significant effect of antenatal GC treatment on the capacity to produce IL-6.

The influence of betamethasone and dexamethasone on motor development in young rats

Synthetic corticosteroids such as dexamethasone and betamethasone are widely used in clinical practice of the perinatal period to enhance lung maturation. However, indications emerged both on the basis of investigations in humans and in experimental animals that such treatment leads to abnormal brain development. In the present study, the neurologic development and the development of locomotion were studied in two groups of rats injected either with dexamethasone or with betamethasone on their 3rd and 4th d, and this was compared with development in a group of control rats injected with saline. Each group consisted of 12 rats. Neurologic reflexes were tested daily and the rat's physical development (body weight and age at eye opening) was noted from the 4th until the 21 st d. Locomotion was recorded on videotape and analyzed during playback runs. Results indicated a growth retardation in both groups of rats treated with corticosteroids, but remarkably, the opening of the eyes was advanced by about 1 d in the dexamethasone group compared with control rats and rats treated with betamethasone. Several reflexes showed normal development, but the negative geotaxis and free-fall righting responses developed retarded. Locomotion in both experimental groups was characterized by a postural tremor and an abnormal posture during walking from the 9th until the 15th d. Although the walking pattern after this age became fluent, the gait width remained abnormally increased until the 20th d. Our results indicate that both dexamethasone and betamethasone interfere with the development of vestibular and cerebellar functions involved in complex motor patterns.

Effect of dexamethasone and betamethasone on fetal heart rate variability in preterm labour: a randomised study

OBJECTIVE

To compare the effects of betamethasone and dexamethasone on fetal heart rate in appropriately grown fetuses.

METHODS

Eighty-two pregnant women (97 fetuses) with preterm labour were randomly allocated to receive betamethasone (n=42) or dexamethasone (n=40) for fetal lung maturation in a nonblinded fashion. Computerised cardiotocogram (CTG) parameters were compared before, during and after treatment.

RESULTS

A decrease in fetal heart rate variability was found with betamethasone but no significant changes were found with dexamethasone. Fetal heart rate variability returned to pre-treatment values within a week after cessation of treatment with betamethasone. Neonatal outcome was similar in the two groups.

CONCLUSIONS

These findings might prove useful in the management of compromised fetuses with decreased fetal heart rate variability in which the CTG should be used together with other parameters to assess fetal wellbeing during corticosteroid treatment. Dexamethasone may be preferable as the drug of choice since it was associated with significantly less alteration in fetal heart rate variability compared with betamethasone.

A randomised controlled comparison of betamethasone with dexamethasone: effects on the antenatal fetal heart rate

OBJECTIVE

To compare the effects of maternal administration of betamethasone and dexamethasone on fetal heart rate, using computerised numerical analyses, and to examine the association between changes in short term variation and the timing and indication for delivery.

SETTING

John Radcliffe Hospital, Oxford.

SAMPLE

Fifty-nine women with singleton pregnancies, who were at risk of delivery before 34 weeks of gestation, had received no steroids in the preceding week and could give informed consent.

METHODS

Women were randomised on a double-blind basis to receive either betamethasone or dexamethasone. The fetal heart rate was recorded (60-minute duration at similar times of day) before steroid administration and on each of the following two days; changes were measured by computerised analyses.

MAIN OUTCOME MEASURES

Changes in short term variation and long term variation of fetal heart rate or the number of fetal movements. Statistical analysis was nonparametric.

RESULTS

Betamethasone and dexamethasone had no differential effects on the computerised cardiotocography. However, both steroids decreased baseline fetal heart rate, increased long term variation, increased short term variation, and decreased fetal movements on the first day after steroid administration, and decreased high fetal heart rate variation and decelerations on the second day. Among 13 women who were delivered within one week of steroid administration, smaller rises in short term variation on day one were associated with delivery for fetal indications.

CONCLUSIONS

Both betamethasone and dexamethasone produced transient, unexplained changes in the fetal heart rate over the two days following steroid administration. Larger changes in short term variation were associated with fetal wellbeing. It is important to recognise that such changes are a physiological response of the human fetus to steroid administration.

Antenatal corticosteroid therapy and fetal behaviour: a randomised study of the effects of betamethasone and dexamethasone

OBJECTIVES

To compare the effects of maternal betamethasone and dexamethasone administration on fetal behaviour and fetal heart rate variation.

DESIGN

A prospective randomised study of 60 women at increased risk of preterm delivery.

OUTCOME MEASURES

Fetal heart rate and its variation, the incidence of fetal body and breathing movements.

SETTING

Obstetric unit, University Hospital, Utrecht, The Netherlands.

RESULTS

Following maternal betamethasone administration (day 2), fetal heart rate variation was reduced by 19% and fetal body and breathing movements by 49% and 85%, respectively. After dexamethasone treatment there was a significant increase in short term fetal heart rate variation (24%) on day 1. All values returned to baseline on day 4, indicating that no fetal deterioration had occurred during the course of the study period.

CONCLUSION

Betamethasone, with probably the greater beneficial effect, has more effects on fetal behaviour and fetal heart rate variation than dexamethasone. When assessing fetal condition, due account needs to be taken of these effects.

A comparative study of cardiovascular, endocrine and behavioural effects of betamethasone and dexamethasone administration to fetal sheep

1. Chronically instrumented, late-gestation fetal sheep were prepared to: (1) characterize cardiovascular, endocrine and behavioural effects of fetal treatment with clinical doses of betamethasone and dexamethasone; (2) define specific differences, if any, in the actions of betamethasone and dexamethasone of measured fetal responses; and (3) assess the contribution of changes in peripheral vascular resistance to the glucocorticoid-induced hypertension. 2. Following baseline, either saline (n = 9), betamethasone (n = 9), or dexamethasone (n = 6) was infused for 48 h in fetal sheep commencing at 125 days of gestation. A pronounced increase in fetal blood pressure occurred following both betamethasone and dexamethasone treatment. The nature and magnitude of this increase was similar following treatment with either glucocorticoid. 3. To address possible mechanisms contributing to the glucocorticoid-induced fetal hypertension, fetal plasma catecholamine levels and changes in fetal femoral haemodynamics were assessed following fetal glucocorticoid treatment. A fall in fetal plasma noradrenaline and adrenaline concentrations occurred during betamethasone and dexamethasone treatment. In contrast, a progressive femoral vasoconstriction occurred during betamethasone treatment. 4. A modest fall in the incidence of fetal breathing movements occurred during fetal treatment with either betamethasone or dexamethasone. The magnitude of this reduction was similar with treatment of either glucocorticoid. The fall in fetal breathing during betamethasone and dexamethasone treatment was not associated with a fall in the incidence of fetal low voltage electrocortical activity. 5. Our results indicate that prenatal betamethasone and dexamethasone treatment of late-gestation fetal sheep, in doses similar to those employed clinically, is associated with fetal cardiovascular, endocrine and behavioural effects. Both betamethasone and dexamethasone induce similar increases in fetal blood pressure and similar falls in the incidence of fetal breathing movements. The pronounced betamethasone-induced fetal hypertension is associated with an increase in fetal femoral vascular resistance.

[Prenatal corticotherapy and acceleration of fetal maturation. II. Results of clinical applications]

Numerous subsequent controlled trials and recent meta-analysis have confirmed the efficiency of antenatal glucocorticoid therapy in reducing both the incidence of respiratory distress syndrome (RDS) and perinatal mortality. Moreover, antenatal glucocorticoid administration reduces the odds of several severe complications relating to immaturity: intraventricular hemorrhage (IVH), ductus arteriosus patency, necrotising enterocolitis, and hemodynamic failure. Exogenous surfactant therapy has not ruled out the benefits of corticosteroids: on the contrary, a synergic effect is obtained when both antenatal and postnatal therapeutic approaches are combined. Very premature infants may also take advantage of the hormonal treatment: in this population, RDS occurrence, IVH incidence and perinatal mortality are also reduced. Unfortunately, despite convincing evidence, the incidence of antenatal steroids therapy has not yet achieved the optimal and desirable level. Obstetricians and pediatricians must be encouraged to ensure high maternal exposure to steroids when preterm delivery is likely to occur.

Developments in CTG analysis

FHR monitoring has been the subject of many debates. The technique, in itself, can be considered to be accurate and reliable both in the antenatal period, when using the Doppler signal in combination with autocorrelation techniques, and during the intrapartum period, in particular when the FHR signal can be obtained from a fetal ECG electrode placed on the presenting part. The major problems with FHR monitoring relate to the reading and interpretation of the CTG tracings. Since the FHR pattern is primarily an expression of the activity of the control by the central and peripheral nervous system over cardiovascular haemodynamics, it is possibly too indirect a signal. In other specialities such as neonatology, anaesthesiology and cardiology, monitoring and graphic display of heart rate patterns have not gained wide acceptance among clinicians. Digitized archiving, numerical analysis and even more advanced techniques, as described in this chapter, have primarily found a place in obstetrics. This can be easily explained, since the obstetrician is fully dependent on indirectly collected information regarding the fetal condition, such as (a) movements experienced by the mother, observed with ultrasound or recorded with kinetocardiotocography (Schmidt, 1994), (b) perfusion of various vessels, as assessed by Doppler velocimetry, (c) the amount of amniotic fluid or (d) changes reflected in the condition of the mother, such as the development of gestation-induced hypertension and (e) the easily, continuously obtainable FHR signal. It is of particular comfort to the obstetrician that a normal FHR tracing reliably predicts the birth of the infant in a good condition, which makes cardiotocography so attractive for widespread application. However, in the intrapartum period, many traces cannot fulfil the criteria of normality, especially in the second stage. In this respect, cardiotocography remains primarily a screening and not so much a diagnostic method. As long as continuous monitoring of fetal acid-base balance has not been extensively tested in clinical practice, microblood sampling of the fetal presenting part (Saling, 1994) is a useful adjunct. The problem with non-normal tracings is that their significance is very often unclear. They may indicate serious fetal distress, finally resulting in preventable destruction of critical areas in the fetal brain and damage to various organs; or, on the contrary, they may indicate temporary changes in cardiovascular control as a reaction to the intermittent effects on fetal haemodynamics of, for example, uterine contractions, whether or not in combination with partial or complete compression of umbilical cord vessels or the vessels on the chorionic plate (van Geijn, 1994). Many factors influence the FHR and its variability, which further complicates the interpretation of FHR patterns; some have been discussed here in some detail. Undoubtedly, there is a need for quantitative and objective FHR analysis, as long as it does not lead to erroneous results. Close collaboration between engineers and clinicians is a prerequisite for further advances in this field. Decision support systems certainly have a future but only if they are able to take into account a large set of clinical data and can combine it with data obtained from FHR signals and other parameters referring to the fetal condition, such as fetal growth, Doppler velocimetry, amniotic fluid volume and biochemical and biophysical data obtained from the mother. Basic technical concepts inherent in computerized CTG analysis, such as sampling rate (Chang et al, 1995), signal loss, artefact detection (van Geijn et al, 1980), further processing of intervals, archiving in digitized format and monitor display, should receive considerable attention. There is still a long way to go until decision support systems find their way into obstetric practice. Further developments can only be achieved thanks to efforts of many basic and clinical researchers, wo