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

Effects of antenatal corticosteroids on fetal hemodynamics: a longitudinal study

Objective

To study the effect of antenatal corticosteroid administration on fetal hemodynamics using longitudinal analysis of Doppler waveforms in the umbilical artery (UA) and middle cerebral artery (MCA).

Materials and Methods

This was a retrospective study that included 30 fetuses at risk for preterm birth. Twenty-eight pregnant women were treated with betamethasone for fetal lung maturation. Doppler examinations of the UA and MCA were performed once before and three or eight times after corticosteroid administration. We used a Bayesian hierarchical linear model. Reference ranges were constructed, and associations between variables (gestational age and pre-eclampsia) were tested.

Results

The mean maternal age, gestational age at betamethasone administration, and gestational age at delivery were 32.6 ± 5.89 years, 30.2 ± 2.59 weeks, and 32.9 ± 3.42 weeks, respectively. On UA Doppler, there was a significant decrease in the pulsatility index (PI) after corticosteroid administration, with a mean of 0.1147 (credibility interval: 0.03687-0.191) in three observations and a median of 0.1437 (credibility interval: 0.02509-0.2627) in eight observations. However, there was no significant change in the Doppler MCA PI, regardless of gestational age and the presence or absence of pre-eclampsia.

Conclusion

Although antenatal corticosteroid administration induced a significant decrease in the Doppler UA PI, we observed no change in the cerebral vasculature.

The role of the fetal biophysical profile in the management of fetal growth restriction

Growth-restricted fetuses are at risk of hypoxemia, acidemia, and stillbirth because of progressive placental dysfunction. Current fetal well-being, neonatal risks following delivery, and the anticipated rate of fetal deterioration are the major management considerations in fetal growth restriction. Surveillance has to quantify the fetal risks accurately to determine the delivery threshold and identify the testing frequency most likely to capture future deterioration and prevent stillbirth. From the second trimester onward, the biophysical profile score correlates over 90% with the current fetal pH, and a normal score predicts a pH >7.25 with a 100% positive predictive value; an abnormal score on the other hand predicts current fetal acidemia with similar certainty. Between 30% and 70% of growth-restricted fetuses with a nonreactive heart rate require biophysical profile scoring to verify fetal well-being, and an abnormal score in 8% to 27% identifies the need for delivery, which is not suspected by Doppler findings. Future fetal well-being is not predicted by the biophysical profile score, which emphasizes the importance of umbilical artery Doppler and amniotic fluid volume to determine surveillance frequency. Studies with integrated surveillance strategies that combine frequent heart rate monitoring with biophysical profile scoring and Doppler report better outcomes and stillbirth rates of between 0% and 4%, compared with those between 8% and 11% with empirically determined surveillance frequency. The variations in clinical behavior and management challenges across gestational age are better addressed when biophysical profile scoring is integrated into the surveillance of fetal growth restriction. This review aims to provide guidance on biophysical profile scoring in the in- and outpatient management of fetal growth restriction.

Sex differences in modulation of fetoplacental vascular resistance in growth-restricted mouse fetuses following betamethasone administration: comparisons with human fetuses

BACKGROUND

Maternally administered corticosteroids are routinely used to accelerate fetal lung maturation in pregnancies at risk of early preterm delivery. Although, among the subgroup with growth restriction, a majority show a temporary improvement in umbilical artery Doppler waveforms that may be sustained up to 7 days, a minority will acutely decompensate in response to corticosteroids in association with deteriorating umbilical and fetal Doppler waveforms. The basis for such acute Doppler changes is presently unknown. Our group has developed a noninvasive ultrasound methodology to measure wave reflections in the umbilical artery and have established that wave reflection metrics are sensitive to structural changes in the placental vasculature and to acute changes in vascular tone. Using this approach, we demonstrated in healthy pregnant mice that fetoplacental vascular resistance decreased in betamethasone-treated mice compared with saline-treated controls.

OBJECTIVE

This study aimed to investigate the effects of betamethasone administration on the wave reflection metrics in a mouse model of fetal growth restriction and to compare these findings with equivalent measurements in human fetuses.

STUDY DESIGN

Pregnant CD-1 mice were housed from embryonic day 14.5 to embryonic day 17.5 in either a normoxic (21% O₂, n=24) or hypoxic environment (11% O₂, n=22), the latter being an established mouse model of fetal growth restriction. To investigate the effect of maternally administered betamethasone on the fetoplacental vasculature, ultrasound imaging was performed at baseline and 4 hours after treatment (either betamethasone or sterile saline). Umbilical artery wave reflection metrics were compared between the groups and for the effect of fetal sex. In addition, a cohort of 10 pregnant women with elevated umbilical artery pulsatility index and evidence of fetal growth restriction and 6 controls were imaged before and after corticosteroid administration.

RESULTS

In the mouse model, after betamethasone administration, the female fetuses from the hypoxia group showed a 15% increase in umbilical artery diameter, a 98% increase in umbilical artery blood flow, and a 27% decrease in umbilical artery reflection coefficient, whereas the males from the hypoxia group showed no substantial changes. In agreement with our mouse findings, umbilical artery reflections were found to be larger in human growth-restricted fetuses than controls in women at risk of preterm birth.

CONCLUSION

Our studies provide insight into the mechanism whereby the human growth-restricted fetus may exhibit a temporary favorable fetoplacental vascular response to maternally administered corticosteroids. Further investigations are needed to understand why the male growth-restricted fetus seems unable to mount this favorable vascular response.

Effect of maternal betamethasone administration on feto-placental vascular resistance in the mouse†

Antenatal corticosteroids are often administered to women at risk of preterm birth to accelerate fetal lung development; however, there is evidence that this treatment may adversely affect placental function in some fetuses. Our group has recently demonstrated that wave reflections in the umbilical artery (UA), measured using high-frequency ultrasound, are sensitive to placental vascular abnormalities. In the present study, we used this approach to investigate the effect of maternal administration of betamethasone, a clinically relevant corticosteroid, on the feto-placental vasculature of the mouse. Fetuses were assessed at embryonic day (E)15.5 and E17.5 in C57BL6/J mice. At both gestational ages, the UA diameter, UA blood flow, and the wave reflection coefficient were significantly elevated in the betamethasone-treated mice compared to vehicle-treated controls. These observations support the interpretation that placental vascular resistance dropped with betamethasone treatment to an extent that could not be explained by vasodilation of the UA alone. Consistent with clinical studies, the effect of betamethasone on UA end-diastolic velocity was heterogeneous. Our results suggest that UA wave reflections are more sensitive to acute changes in placental vascular resistance compared with the UA pulsatility index, and this technique may have clinical application to identify a favorable placental vascular response to fetal therapies such as antenatal corticosteroids, where the fetal heart rate is likely to vary.

Cardiovascular effects of prenatal stress-Are there implications for cerebrovascular, cognitive and mental health outcome?

Prenatal stress programs offspring cognitive and mental health outcome. We reviewed whether prenatal stress also programs cardiovascular dysfunction which potentially modulates cerebrovascular, cognitive and mental health disorders. We focused on maternal stress and prenatal glucocorticoid (GC) exposure which have different programming effects. While maternal stress induced cortisol is mostly inactivated by the placenta, synthetic GCs freely cross the placenta and have different receptor-binding characteristics. Maternal stress, particularly anxiety, but not GC exposure, has adverse effects on maternal-fetal circulation throughout pregnancy, probably by co-activation of the maternal sympathetic nervous system, and by raising fetal catecholamines. Both effects may impair neurodevelopment. Experimental data also suggest that severe maternal stress and GC exposure during early and mid-gestation may increase the risk for cardiovascular disorders. Human data are scarce and especially lacking for older age. Programming mechanisms include aberrations in cardiac and kidney development, and functional changes in the renin-angiotensin-aldosterone-system, stress axis and peripheral and coronary vasculature. Adequate experimental or human studies examining the consequences for cerebrovascular, cognitive and mental disorders are unavailable.

Effect of maternal corticosteroid provision on middle cerebral artery peak systolic velocity readings in the potentially anaemic fetus prior to planned intrauterine transfusion

Purpose

Middle Cerebral Artery Peak Systolic Velocity (MCA-PSV) is the main tool for determining need for and timing of intrauterine transfusions (IUT) for severe fetal anaemia. It has been suggested that steroids temporarily decrease MCA-PSV, potentially increasing false-negative MCA-PSV findings in anaemic fetuses. We therefore aimed to assess whether maternal corticosteroid administration prior to IUT is associated with clinically significant temporary decreases in MCA-PSV.

Methods

Retrospective review 2005-2016 of steroid provision prior to IUT, with correlation of MCA-PSV pre- and post-steroid administration and haemoglobin at IUT.

Results

In 23 identified cases, there was no significant difference between average MoM pre- and post-steroid (1.71 ± 0.41 vs. 1.66 ± 0.38, -2.9% mean, P = 0.4). There was also no significant difference between pre- and post-steroid MoM taken within 3 days of each other (n = 19, P = 0.21). However, post-steroid MCA-PSV decreased by >15% in 6/23 cases (A-B zone in two cases, B-C zone in one case).

Conclusions

This study found no sizeable, generalised effect of corticosteroid administration on MCA-PSV readings in the potentially anaemic fetus. A minority showed substantial shifts where reliance on post-steroid MCA-PSV could have unfavourably altered clinical management. Ultimately, further large-scale research is required before we can discount the potential impact of steroids on MCA-PSV values.

Does antenatal betamethasone have negative effects on fetal activities and hemodynamics in cases of preeclampsia without severe features? A prospective, placebo-controlled, randomized study

AIM

To evaluate whether antenatal betamethasone affects the fetal biophysical profile (BPP) and Doppler indices of umbilical and middle cerebral arteries (MCAs) in cases of preeclampsia without severe features.

MATERIALS AND METHODS

Forty singleton preeclamptic pregnancies without severe features at gestational ages of 28-34 weeks were randomly divided into two groups of 20 patients: betamethasone and control groups. Patients in the betamethasone group were administered two consecutive doses of 12 mg betamethasone intramuscularly, 24 h apart, and patients in the control group were administered the same volume of saline as a placebo. All participants were evaluated before (0 h) and at hours 24, 48, and 72 of betamethasone/placebo administration using BPP scoring and umbilical and MCA Doppler examinations.

RESULTS

Total BPP scores were significantly lower in the betamethasone group across the three time points during the follow-up period (p < 0.001). None of the Doppler indices differed significantly between the groups (p > 0.05).

CONCLUSION

Antenatal betamethasone negatively affects fetal BPP score parameters, including the non-stress test, fetal body and breathing movements, without affecting vascular indices of umbilical arteries and MCAs. Clinician awareness of this transient drug-induced effect might be valuable for preventing iatrogenic preterm delivery for fetuses in preeclamptic pregnancies without severe features.

Effect of antenatal betamethasone administration on Doppler velocimetry of fetal and uteroplacental vessels: a prospective study

OBJECTIVES

To examine the effect of antenatal betamethasone administration on Doppler parameters of fetal and uteroplacental circulation.

METHODS

Seventy-six singleton pregnancies that received betamethasone therapy were prospectively evaluated. Doppler measurements of pulsatility indices (PI) in fetal umbilical artery (UA), middle cerebral artery (MCA), ductus venosus and maternal uterine arteries were performed before (0 h) and 24, 48, 72 and 96 h after the first dose of betamethasone. Women with positive end-diastolic flow (EDF) in UA and those with absent or reversed EDF in UA were evaluated separately.

RESULTS

Fifty-two women with EDF in UA and 24 women with absent or reversed flow in UA were examined. Administration of maternal betamethasone was followed by a significant decrease in the PI of the MCA at 24 h (P<0.05). Additionally, return of absent to positive, reversed to absent or from reversed to positive diastolic flow in UA was detected within 24 h in 19 (79.2%) fetuses with absent or reversed UA-EDF. All alterations were transient and maintained up to 72 h.

CONCLUSIONS

Antenatal administration of betamethasone is associated with significant but transient changes in the fetal blood flow. Hence, intensive surveillance of fetuses with Doppler ultrasonography is warranted following betamethasone therapy.

Comparison of effects of nifedipine and ritodrine on maternal and fetal blood flow patterns in preterm labor

OBJECTIVE

The aim of this study was to investigate and compare the effects of nifedipine and ritodrine treatment on fetomaternal blood flow parameters in women with preterm labor.

MATERIAL AND METHODS

Sixty women with gestational age between 24 and 36 weeks admitted to the obstetrics clinic for preterm labor were enrolled in this study. Patients were randomly assigned to receive either nifedipine (n=30) or ritodrine (n=30) treatment. Demographic features, clinic and laboratory parameters, fetal and maternal side effects, and Doppler ultrasound indices of the umbilical artery (UA), uterine arteries (UtA), and middle cerebral artery (MCA) before, 2 hours after, and 48 hours after the initiation of tocolytic treatments were compared between the two groups.

RESULTS

In both the groups, early- and late-onset changes in the pulsatility index (PI) and other Doppler indices for UA, UtA, and MCA were similar. In addition, time elapsed till delivery, fetal mortality, and maternal morbidity in both the groups were not statistically significant (p>0.05). However, maternal side effects such as tachycardia was more frequent (p<0.05) in the ritodrine group. Besides, in the ritodrine group, anxiety was only minimally observed.

CONCLUSION

Nifedipine and ritodrine used as tocolytic agents did not significantly alter early- and late-onset changes in Doppler ultrasonography parameters in fetal and fetomaternal circulation.

Comparing the effects of antenatal betamethasone on Doppler velocimetry between intrauterine growth restriction with and without preeclampsia

Evaluation of the effects of betamethasone on patients with intrauterine growth restriction in couple with preeclampsia is not well studied. This study was designed to assess and compare the changes of Doppler flow in maternal, fetal and placental arteries in singleton pregnancies complicated by IUGR and preeclampsia which are at 24-34 weeks of gestation after betamethasone therapy. This prospective, longitudinal and multicenter study was conducted in 2013 on the 40 singleton pregnant women with IUGR fetuses and concerned over maternal or fetal well-being. Three Doppler measurements including absolutely before betamethasone, one day after betamethasone and 5 days after betamethasone administration were performed. Flow velocity waveforms were obtained from uterine arteries (UA), Umbilical (UM), and middle cerebral artery (MCA). The Systolic/Diastolic ratio (S/D), Resistance Index (RI), and Pulsatility Index (PI) were determined for waveforms. Comparison of baseline mean scores between IUGR with and without preeclampsia showed no statistically significant differences. The mean scores of UA, MCA-UM-RI, UM-S/D, UM-PI, and UM-RI did not differ statistically significant between three time points when compared trend between negative and positive preeclampsia subjects. However, UM-RI had close P value to the margin of statistical significance (P value = 0.055). In other words, in our study, UM-RI had a clear tendency to be significance. We can conclude that preeclampsia alone could not be major prognostic factor in pregnancies with IUGR. While, other prognostic factors such as gestational age, fetal weight, and fetal vascular Doppler flow may are more important for decision making about termination of preeclampsia.

The effect of maternal betamethasone administration on Doppler flow velocity parameters of the fetal branch pulmonary artery

To investigate the effects of antenatal betamethasone on fetal pulmonary blood flow velocity waveforms. The study comprised 28 women with singleton pregnancies at high risk for preterm delivery. They were treated with two doses of 12 mg betamethasone intramuscularly 24 h apart to enhance lung maturity. Flow velocity waveforms were recorded with Doppler ultrasound from the middle segment of pulmonary artery (PA). Compared with the pretreatment mean value, a significant decrease in the pulmonary artery pulsatility (PI) and the resistance indexes (RI) was noted at 24 h and 48 h after the administration of first dose of betamethasone (p = 0.022 and p = 0.018 for PI and p = 0.001 and p = 0.004 for RI, respectively). After 7 days, the pulmonary artery velocity waveforms returned to the types of waveform observed before treatment (p = 0.216 for PI and p = 0.249 for RI). Maternal antenatal betamethasone resulted in a significant transient decrease in the pulsatility and the resistance indexes in the pulmonary artery. These findings indicate a direct effect of betamethasone on fetal pulmonary circulation.

The short term fetal cardiovascular effects of corticosteroids used in obstetrics

Background: Corticosteroids are widely used in obstetrics due to their striking effect on perinatal morbidity and mortality of premature neonates. Despite this, relatively few studies have explored short term fetal effects of corticosteroids as measured by ultrasound. Objectives: 1) To present a literature review of short term fetal cardiovascular effects of corticosteroids 2) To describe the protocol of a current observational study (SUPER-A*STEROID) of cardiovascular effects of dexamethasone and betamethasone in the first week after their administration. This trial is nested within the A*STEROID blinded multicentre randomised controlled trial of the two steroid preparations. Findings: Existing data suggest corticosteroids have little effect on the major measured fetal blood vessels when the baseline ultrasound is normal. In the compromised fetus, where the umbilical artery end-diastolic flow is abnormal prior to maternal corticosteroids, flow is temporarily restored in approximately 50% of cases. Whether such changes are beneficial is uncertain. Very little data exist that directly compare the short-term effects of betamethasone and dexamethasone. The SUPER- A*STEROID study described will help provide this information.

The uses and limitations of the fetal biophysical profile

In the second half of the twentieth century, true antepartum fetal assessment became possible, mainly due to the advent of real-time ultrasound. Initially, the most widely used form of antepartum fetal assessment was electronic fetal heart rate monitoring, through the nonstress test or the oxytocin-induced contraction stress test. It was soon realized, however, that these forms of monitoring had significant limitations. The biophysical profile allows a more thorough evaluation of fetal well-being and has the potential to significantly reduce the false-positive rate of the nonstress test/contraction stress test.

The effects of ritodrine and magnesium sulfate on maternal and fetal Doppler blood flow patterns in women with preterm labor

OBJECTIVE

To determine the effects of ritodrine and magnesium sulfate on maternal-fetal blood flows.

STUDY DESIGN

A total of 85 pregnant women between 26th and 36th weeks with preterm labor, and 83 healthy pregnant women were included. Patients in the study group were randomly assigned to receive either ritodrine (with the addition of verapamil) (n=46) or magnesium sulfate (n=39). Blood flow examinations on the umbilical artery (UA), middle cerebral artery (MCA), bilateral uterine arteries (Ut.A) and ductus venosus (DV) were performed before and 48 h after initiating therapy.

RESULTS

UA pulsatility index (PI) significantly differed in women receiving tocolysis compared to controls after 48 h. DV PI increased in women receiving MgSO(4), whereas it decreased in the ritodrine and control groups. Ut.A values did not significantly change after 48 h in the groups. In women between the 26th and 32nd weeks, UA, MCA and DV PI did not significantly change after 48 h in the three groups. However, in women between the 32nd and 36th weeks UA and MCA PI significantly differed in the treatment groups compared to controls after 48 h. DV PI increased in women receiving MgSO(4), whereas it decreased in the ritodrine and control groups.

CONCLUSIONS

MgSO(4) and ritodrine affect blood flow patterns after 48 h in some maternal-fetal vessels. These effects on blood flow are particularly significant in women between 32nd and 36th weeks. The effects of both drugs on fetal and maternal Doppler flows seem similar, except the increased resistance to flow in DV in women receiving MgSO(4).

Antenatal corticosteroid therapy: short-term effects on fetal behaviour and haemodynamics

Antenatal corticosteroid therapy to enhance fetal lung maturity in threatened preterm delivery has a number of non-pulmonary side-effects, both beneficial and undesirable. This review focuses on the short-term (transient) effects of betamethasone and dexamethasone on aspects of fetal circulation and behaviour which are used clinically as markers of fetal well-being. We summarise the effects observed, discuss the proposed underlying mechanisms, and emphasise the consequences for clinical decision-making. Recommendations are given to optimise medical care and to minimise the risk of unwarranted iatrogenic preterm delivery.

Biophysical profile for fetal assessment in high risk pregnancies

BACKGROUND

A biophysical profile (BPP) includes ultrasound monitoring of fetal movements, fetal tone and fetal breathing, ultrasound assessment of liquor volume with or without assessment of the fetal heart rate. The BPP is performed in an effort to identify babies that may be at risk of poor pregnancy outcome, so that additional assessments of wellbeing may be performed, or labour may be induced or a caesarean section performed to expedite birth.

OBJECTIVES

To assess the effects of the BPP when compared with conventional monitoring (CTG only or MBPP) on pregnancy outcome in high-risk pregnancies.

SEARCH STRATEGY

We searched the Cochrane Pregnancy and Childbirth Group's Trials Register (October 2007), CENTRAL (The Cochrane Library 2006, Issue 4), MEDLINE (1966 to November 2006), EMBASE (1974 to November 2006) and CINAHL (1980 to November 2006).

SELECTION CRITERIA

Randomised and quasi-randomised controlled trials involving a comparison of fetal BPP with other forms of antepartum fetal assessment in women with high-risk pregnancies.

DATA COLLECTION AND ANALYSIS

Two authors independently assessed eligibility, quality and extracted data.

MAIN RESULTS

We included five trials, involving 2974 women. Most trials were not of high quality. Although the overall incidence of adverse outcomes was low, available evidence from randomised controlled trials does not support the use of BPP as a test of fetal wellbeing in high-risk pregnancies. We found no significant differences between the groups in perinatal deaths (relative risk (RR) 1.33, 95% confidence interval (CI) 0.60 to 2.98) or in Apgar score less than seven at five minutes (RR 1.27, 95% CI 0.85 to 1.92). Combined data from the two high-quality trials suggest an increased risk of caesarean section in the BPP group RR 1.60, 95% CI 1.05 to 2.44, n = 280, interaction test P = 0.03. However, the number of participating women was relatively small (n = 280). Therefore, additional evidence is required in order to be definitive regarding the efficacy of this test in high-risk pregnancies. Furthermore, the impact of the BPP on other interventions, length of hospitalisation, serious short-term and long-term neonatal morbidity and parental satisfaction requires further evaluation.

AUTHORS' CONCLUSIONS

At present, there is insufficient evidence from randomised trials to support the use of BPP as a test of fetal wellbeing in high-risk pregnancies.

Guidelines for the management of spontaneous preterm labor

Preterm birth is defined as delivery at <37 completed weeks of pregnancy (World Health Organization). Spontaneous preterm birth (SPB) includes preterm labor, preterm spontaneous rupture of membranes, preterm premature rupture of membranes (PPROM) and cervical weakness; it does not include indicated preterm delivery for maternal or fetal conditions. Early SPB (<32 weeks' gestation) is associated with an increased higher perinatal mortality rate, inversely proportional to gestational age. The pathophysiologic events that trigger SPB are largely unknown but include decidual hemorrhage (abruption), mechanical factors (uterine overdistention or cervical incompetence), and hormonal changes (perhaps mediated by fetal or maternal stress). In addition, several cervicovaginal infections have been associated with preterm labor. SPB is also the leading cause of long-term morbidity, including neurodevelopmental handicap, cerebral palsy, seizure disorders, blindness, deafness and non-neurological disorders, such as bronchopulmonary dysplasia and retinopathy of prematurity. Delaying delivery may reduce the rate of long-term morbidity by facilitating the maturation of developing organs and systems. The benefits of administration of antepartum glucocorticosteroids to reduce the incidence and severity of respiratory distress syndrome may be exploited by delay. Delay may also permit transfer of the fetus in utero to a center with neonatal intensive care unit facilities. There is considerable variation in the way that spontaneous preterm labor (SPTL) is diagnosed, managed and treated internationally. The development of clinical guidelines requires an evidence-based approach to improve outcome and allow more efficient use of resources. With recent advances in our understanding of the etiology and mechanisms of SPTL and the availability of safer, more specific tocolytics, it was felt that guidelines should be developed to achieve, if possible, an European consensus in patient diagnosis, management and treatment.

Nifedipine therapy for preterm labor: effects on placental, fetal cerebral and atrioventricular Doppler parameters in the first 48 hours

OBJECTIVE

To assess the effect of nifedipine tocolysis on Doppler parameters of the uterine, umbilical and fetal middle cerebral arteries and atrioventricular valves in the first 48 h of therapy.

METHODS

Doppler waveforms of uterine, umbilical and middle cerebral arteries and both atrioventricular valves were measured from 28 pregnant women and fetuses prior to and during nifedipine therapy for preterm labor. Maternal and fetal heart rates (FHR), maternal systolic and diastolic blood pressure, and the Doppler pulsatility index (PI) of the uterine, umbilical and middle cerebral arteries were measured. The cerebroplacental ratio (middle cerebral artery PI/umbilical artery PI) was calculated. The total time velocity integrals (TVIs) of tricuspid and mitral valves and their E- and A-wave peak velocity ratio (E/A) were measured. Friedman repeated-measures analysis of variance was used to compare the variables before and after nifedipine therapy. If significant differences were found, Wilcoxon's signed ranks test was used to analyze the difference between the two variables. A P-value of < 0.05 was considered significant.

RESULTS

Nifedipine maintenance was associated with a significant decline in maternal systolic and diastolic blood pressure after 24 h, while maternal heart rate and FHR were unaffected. The uterine artery PI had decreased significantly at 24 and 48 h, while the umbilical artery PI did not change significantly. The middle cerebral artery PI had decreased significantly at 24 and again at 48 h. A significant fall in the cerebroplacental Doppler ratio was maintained beyond 24 h. The mean E/A values, TVIs and TVI x FHR values at 24 and 48 h were unchanged from the baseline values.

CONCLUSIONS

Nifedipine maintenance tocolysis is associated with a significant decline in uterine artery and middle cerebral artery Doppler indices 24 h after the first dose. Fetal cardiac diastolic function is unaffected and the significant redistribution observed after 24 h is likely to be attributable to altered cerebral blood flow.

Antenatal corticosteroid therapy: a comparative study of dexamethasone and betamethasone effects on fetal Doppler flow velocity waveforms

OBJECTIVE

To compare the effects of antenatal administration of dexamethasone and betamethasone, used in two different regimens, on fetal Doppler flow velocities.

STUDY DESIGN

Sixty-seven women at risk for preterm delivery received course of corticosteroids by means of a computer-generated randomization table. The Doppler examination of the pulsatility index (PI) of the umbilical artery (UA), the middle cerebral artery (MCA) and the middle cerebral artery/umbilical artery PI ratio (MCA PI/UA PI) were performed before treatment, 24 and 72 h after the first dose of corticosteroids. The SAS system was used to perform statistical analysis.

RESULTS

No significant change was observed in UA PI through dexamethasone therapy. In MCA there was a significant decrease in PI at 72 h (2+/-0.43 before and 1.68+/-0.31 after, p=0.0001). Similarly a significant decrease in MCA PI/UA PI ratio was noted (2.09+/-0.51 before and 1.83+/-0.4 after, p=0.0137). No significant changes were observed in UA PI, MCA PI and MCA PI/UA PI ratio during betamethasone treatment.

CONCLUSIONS

Our results indicate significant decrease in fetal middle cerebral artery impedance at 72 h after maternal administration of the first dose of dexamethasone. Effects of dexamethasone on fetal brain warrants further research.

Mega-dose carbamazepine complicating third trimester of pregnancy

A case of coma due to carbamazepine ingestion with the intention of committing suicide at 33 weeks' gestation is presented. Management included activated charcoal administration and exchange plasmapheresis. A fetal non-stress test was non-reassuring but the Apgar score, cord blood gases and early neonatal outcome were normal. Differential diagnosis of coma in pregnancy should include investigation for drug intoxication.

Cardiovascular and endocrine effects of a single course of maternal dexamethasone treatment in preterm fetal sheep

OBJECTIVE

To determine the effects of a single course of maternally administered dexamethasone on preterm fetal sheep in utero.

DESIGN

Prospective randomised controlled trial.

SETTING

University laboratory.

SAMPLE

Pregnant sheep at 0.7 of gestation.

METHODS

Pregnant ewes at 103 days of pregnancy (term = 147 days) were given two intramuscular injections of vehicle (n= 7) or 12 mg of dexamethasone (DEX; n= 8) 24 hours apart. Fetuses were continuously monitored for five days.

MAIN OUTCOME MEASURES

Fetal mean arterial blood pressure, carotid and femoral arterial blood flow and vascular resistance, heart rate, heart rate variability, fetal plasma cortisol and ACTH and fetal body movements.

RESULTS

DEX injections led to an acute increase in mean arterial blood pressure with a rise in carotid and femoral vascular resistance, a fall in femoral arterial blood flow, and a brief fall in fetal heart rate followed by significant tachycardia. From 24 hours after the injections, mean arterial blood pressure and vascular resistance returned to control values, however, a mild tachycardia [200 (3) vs 184 (4) bpm, P < 0.05] and loss of the circadian pattern of fetal heart rate variability persisted until the end of recording. Plasma ACTH and cortisol were markedly suppressed by DEX (P < 0.05), with values returning to control levels 32 and 72 hours after the first injection, respectively. There was no effect on basal fetal heart rate variability, body movements, carotid arterial blood flow, or the circadian pattern of fetal heart rate.

CONCLUSION

In contrast to previous experiments utilising direct fetal infusion of steroids, maternal administration of DEX was associated with only transient hypertension.

Diagnosis and management of intrauterine growth restriction

The growth-restricted fetus is a fetus who fails to reach his growth potential and is at risk for perinatal morbidity and mortality. When a fetus has an estimated weight below the 10th percentile, in the absence of congenital anomalies and in the presence of a normal amount of amniotic fluid, Doppler velocimetry gives the most important information to differentiate the truly growth-restricted fetus from the fetus that is constitutionally small but otherwise normal. One area of debate and research is whether Doppler velocimetry can help in timing the delivery of the growth-restricted fetus. Data appear to support the use of ductus venosus velocimetry in deciding when to deliver, but randomized data on this point are still lacking.

Effect of antenatal glucocorticoid therapy on arterial and venous blood flow velocity waveforms in severely growth-restricted fetuses

OBJECTIVE

To study the effects of antenatal glucocorticoid (betamethasone) therapy on blood flow velocity waveform patterns in the umbilical artery (UA), middle cerebral artery (MCA) and ductus venosus (DV) in severely intrauterine growth-restricted (IUGR) fetuses.

METHODS

Fifty-five severely IUGR fetuses at 24-34 weeks of gestation were included in the study. The effect of antenatal glucocorticoid administration on Doppler findings in the UA, MCA and DV was studied using two statistical approaches, namely paired sample analysis and multilevel analysis.

RESULTS

There were no effects of betamethasone on the pulsatility index (PI) of the vessels studied. The only changes noticed during the 14 days of observation were a gradual decrease of PI in the MCA, an increase in the UA-PI/MCA-PI ratio and an increase in the DV-PI. These changes with time may be explained by a progressive and gradual deterioration of the fetal condition.

CONCLUSION

Antenatal glucocorticoids (betamethasone) do not affect fetal Doppler waveform patterns of the UA, MCA and DV in severely IUGR fetuses.