The short-term effect of nifedipine tocolysis on placental, fetal cerebral and atrioventricular Doppler waveforms

Fetal echocardiographic evaluation before and after nifedipine treatment in preterm labor

OBJECTIVE

To assess the effect of nifedipine used for tocolysis on cardiac morphology and functions.

METHODS

The study included 47 pregnant women diagnosed with preterm labor at 32-33 weeks. Fetal echocardiographic evaluation was performed with two-dimensional (2D) imaging, M-mode, pulsed wave (PW) Doppler, and tissue Doppler imaging (TDI) before and after the 48^th hour of nifedipine treatment.

RESULTS

No significant change was observed in Doppler parameters (pulsatility indices of the umbilical artery, middle cerebral artery, ductus venosus) and cardiac morphology (cardiothoracic ratio, end-diastolic longitudinal diameters, sphericity indices, wall thickness) after nifedipine treatment. The parameters obtained with TDI (e', a', s', e'/a', E/e' of mitral and tricuspid valves), M- mode (TAPSE, MAPSE), pulsed Doppler (myocardial performance index, left cardiac output, right cardiac output, tricuspid E, A waves, tricuspid E/A ratio, mitral E, A waves, mitral E/A ratio) did not change after nifedipine treatment.

CONCLUSION

To date, this is the first study to examine the effects of nifedipine on the fetal heart using the TDI. Since nifedipine is a drug that is frequently used and well-tolerated in the prevention of preterm labor, it is crucial that it does not cause changes in fetal cardiac parameters during tocolysis. Therefore, we used TDI in addition to conventional methods to evaluate the effect of nifedipine, which is frequently used in obstetrics, on cardiac functions in the early period. Nifedipine treatment seems not to affect systolic or diastolic functions. This indicates that nifedipine is reliable on cardiac functions and morphology in pregnancies treated for preterm labor.

Tocolysis with nifedipine versus atosiban and perinatal outcome: an individual participant data meta-analysis

Background

Worldwide, nifedipine and atosiban are the two most commonly used tocolytic agents for the treatment of threatened preterm birth. The aim of this study was to evaluate the effectiveness of nifedipine and atosiban in an individual participant data meta-analysis (IPDMA).

Methods

We investigated the occurrence of adverse neonatal outcomes in women with threatened preterm birth by performing an IPDMA, and sought to identify possible subgroups in which one treatment may be preferred. We searched PubMed, Embase, and Cochrane for trials comparing nifedipine and atosiban for treatment of threatened preterm birth between 24^0/7 and 34^0/7 weeks’ gestational age. Primary outcome was a composite of perinatal mortality and neonatal morbidities including respiratory distress syndrome, intraventricular haemorrhage, periventricular leucomalacia, necrotising enterocolitis, and sepsis. Secondary outcomes included NICU admission, prolongation of pregnancy and GA at delivery. For studies that did not have the original databases available, metadata was used. This led to a two-stage meta-analysis that combined individual participant data with aggregate metadata.

Results

We detected four studies (N = 791 women), of which two provided individual participant data (N = 650 women). The composite neonatal outcome occurred in 58/364 (16%) after nifedipine versus 69/359 (19%) after atosiban (OR 0.76, 95%CI 0.47–1.23). Perinatal death occurred in 14/392 (3.6%) after nifedipine versus 7/380 (1.8%) after atosiban (OR 2.0, 95%CI 0.80–5.1).

Nifedipine results in longer prolongation of pregnancy, with a 18 days to delivery compared with 10 days for atosiban (HR 0.83 (96% CI 0.69–0.99)). NICU admission occurred less often after nifedipine (46%) than after atosiban (59%), (OR 0.32, 95%CI 0.14–0.75). The sensitivity analysis revealed no difference in prolongation of pregnancy for 48 hours (OR 1.0, 95% CI 0.73–1.4) or 7 days (OR 1.3, 95% CI 0.85–5.8) between nifedipine and atosiban. There was a non-significant higher neonatal mortality in the nifedipine-exposed group (OR 1.4, 95% CI 0.60–3.4).

Conclusions

In this IPDMA, we found no differences in composite outcome between nifedipine and atosiban in the treatment of threatened preterm birth. However, the non-significant higher mortality after administering nifedipine warrants further investigation of the use of nifedipine as a tocolytic drug.

Study registration

We conducted this study according to a prospectively prepared protocol, registered with PROSPERO (the International Prospective Register of Systematic Reviews) under CRD42016024244.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12884-022-04854-1.

Maternal and fetal parameters in pregnant woman undergoing tocolysis with nifedipine

Abstract Objectives: to evaluate the effects of nifedipine with tocolysis under maternal and fetal parameters. Methods: a cohort study with 40 pregnant women admitted at a high-risk pregnancy ward to inhibit premature labor between September/2010 to May/2012. Nifedipine was used as a 20mg sublingual attack dose and maintained 20mg every six and eight hours orally. The variables of the analysis were fetal heart rate (FHR), maternal heart rate (MHR), systolic blood pressure (SBP) and diastolic blood pressure (DBP), and amniotic fluid index (AFI). All the variables were evaluated prior to administrating nifedipine and approximately after 6 hours and every 24 hours, until hospital discharge. Results: there were no modification of the FHR (p=0.48) and the SBP (p=0.29). The MHR increased after 24 hours, but with no statistical difference (p=0.08), returning to similar levels as at admission within 48 hours. The DBP decreased at 6 (p=0.04) to 72 hours, being stable afterwards. The AFI decreased significantly at 24, 48 and 72 hours. Conclusions: the use of high doses of nifedipine with tocolysis causes a decrease of the maternal’s diastolic blood pressure and consequently decreases the amniotic fluid index, but probably without any clinical repercussions.

Drugs for the Treatment and Prevention of Preterm Labor

Preterm birth can be medically-indicated or spontaneous. Almost half of spontaneous preterm deliveries are preceded by preterm labor. Preterm labor is a clinical diagnosis characterized by regular uterine contractions (painful or painless) with concomitant cervical change. This article discusses the prevention and treatment of spontaneous preterm labor utilizing progesterone and tocolytic agents and provides management recommendations in patients with and without a history of prior spontaneous preterm birth.

An effect of maternal nifedipine therapy on fetoplacental blood flow: a prospective study

PURPOSE

The aim of this study is to assess the effects of maternal nifedipine administration on placental and fetal blood flow.

METHODS

A total of 29 patients with preterm labor diagnosis admitted to the tertiary care center, Zeynep Kamil Hospital, were evaluated. Before and 24-48 h after administration of oral nifedipine, Doppler ultrasound scan was carried out to measure fetal middle cerebral artery, ductus venosus, umbilical artery, and maternal uterine artery blood flow.

RESULTS

After 24 and 48 h of therapy, there were no changes in mean PI and RI in the umbilical arteries and ductus venosus (p > 0.05). Fetal middle cerebral artery and maternal uterine artery PI and RI values showed a significant reduction 24-48 h after oral nifedipine therapy (p < 0.05).

CONCLUSIONS

Our study showed that 24 and 48 h after oral nifedipine therapy, there is a significant increase in fetal MCA and maternal uterine artery blood flow, while fetal umbilical artery and ductus venosus Doppler values do not change.

Effects of betamethasone on fetoplacental and maternal hemodynamics in preterm pregnancies

OBJECTIVE

To evaluate the possible effects of prenatal steroid administration on Doppler parameters of the umbilical artery, uterine artery, middle cerebral artery, and ductus venosus, the cerebroplacental ratio, and the amniotic fluid index in preterm fetuses.

METHODS

The present prospective observational study was performed at the Perinatology Department of Trakya University, Edirne, Turkey, between June 1, 2015, and September 1, 2016. It included patients with healthy singleton pregnancies who had received betamethasone at 24-34 weeks of pregnancy. Doppler parameters were measured before (0 hours) and 24, 48, and 72 hours after the administration of betamethasone (two intramuscular doses of 12 mg each, administered 24 hours apart).

RESULTS

There were 68 patients included. Pairwise comparisons demonstrated that, at 72 hours after betamethasone administration, the umbilical artery resistance index (P=0.038), the middle cerebral artery systolic/diastolic velocity ratio (P=0.007), and the amniotic fluid index (P=0.017) were reduced, whereas the end-diastolic velocity of the middle cerebral artery was increased (P=0.012), compared with baseline values.

CONCLUSION

Betamethasone had favorable effects on fetal cerebral circulation, with increased end-diastolic velocity in the middle cerebral artery; this could represent a positive effect on cerebral blood circulation and decreased flow resistance in the umbilical artery.

Nifedipine increases fetoplacental perfusion

AIM

Our aim is to evaluate the effect of nifedipine on fetoplacental hemodynamic parameters.

METHODS

A retrospective study was conducted at a tertiary center with 30 patients for whom nifedipine treatment was used as a tocolytic therapy for preterm labor. Initiation of this treatment was at 31.6±2.5 weeks of gestation. We combined the pulse Doppler imaging parameters with grayscale imaging via the Bernoulli theorem, which is called the "continuity equation", to get the fetoplacental perfusion (FPP). Evaluated parameters were the resistance index (RI), the pulsatility index (PI), systole/diastole ratios (S/D), the velocity-time integral of the umbilical artery (VTI), the radius of the umbilical artery, the peak systolic velocity and the mean pressure gradient in the umbilical artery. From these parameters, the FPP was acquired.

RESULTS

We found that the RI, the PI and the S/D ratio did not change after treatment with nifedipine. The mean pressure gradient, the VTI and the peak systolic velocity increased after treatment with nifedipine. Nifedipine increases FPP from 166±73.81 beat.cm3/min to 220±83.3 beat.cm3/min.

DISCUSSION

Although nifedipine had no effect on the PI, the RI or the S/D, it increased the mean pressure gradient, the VTI and FPP.

Nifedipine versus placebo in the treatment of preterm prelabor rupture of membranes: a randomized controlled trial: Assessment of perinatal outcome by use of tocolysis in early labor-APOSTEL IV trial

OBJECTIVE

Preterm birth is the most common cause of neonatal morbidity and mortality. Around one third of preterm deliveries starts with preterm prelabor rupture of membranes (PPROM). The aim of this trial was to study the effect of prolonged tocolysis with nifedipine versus placebo in women with PPROM on perinatal outcome and prolongation of pregnancy.

STUDY DESIGN

The Apostel IV was a nationwide multicenter randomized placebo controlled trial. We included women with PPROM without contractions between 24(+0) and 33(+6) weeks of gestation. Participants were randomly allocated to daily 80mg nifedipine or placebo, until the start of labor, with a maximum of 18 days. The primary outcome measure was a composite of poor neonatal outcome, including perinatal death, bronchopulmonary dysplasia, periventricular leukomalacia>grade 1, intraventricular hemorrhage>grade 2, necrotizing enterocolitis>stage 1 and culture proven sepsis. Secondary outcomes were gestational age at delivery and prolongation of pregnancy. Analysis was by intention to treat. To detect a reduction of poor neonatal outcome from 30% to 10%, 120 women needed to be randomized.

TRIAL REGISTRY

NTR 3363.

RESULTS

Between October 2012 and December 2014 we randomized 25 women to nifedipine and 25 women to placebo. Due to slow recruitment the study was stopped prematurely. The median gestational age at randomization was 29.9 weeks (IQR 27.7-31.3) in the nifedipine group and 27.0 weeks (IQR 24.7-29.9) in the placebo group. Other baseline characteristics were comparable. The adverse perinatal outcome occurred in 9 neonates (33.3%) in the nifedipine group and 9 neonates (32.1%) in the placebo group (RR 1.04, 95% CI 0.49-2.2). Two perinatal deaths occurred, both in the nifedipine group. Bronchopulmonary dysplasia was seen less frequently in the nifedipine group (0% versus 17.9%; p=0.03). Prolongation of pregnancy did not differ between the nifedipine and placebo group (median 11 versus 8 days, HR 1.02; 95% CI 0.58-1.79).

CONCLUSION

This randomized trial did not show a beneficial effect of prolonged tocolysis on neonatal outcomes or prolongation of pregnancy in women with PPROM without contractions. However, since results are based on a small sample size, a difference in effectiveness cannot be excluded.

A comparison of the effects of the most commonly used tocolytic agents on maternal and fetal blood flow

Objective:

To investigate the effects of two tocolytics, nifedipine and magnesium sulfate, on Doppler indices in maternal and fetal vessels.

Materials and Methods:

We recruited 100 pregnant women with preterm birth between 24-36 gestational weeks who were admitted to our tertiary center over a two-year period. Patients were allocated to nifedipine (n=49) and magnesium sulfate (n=51) groups and Doppler indices of umbilical, middle cerebral, uterine arteries, and ductus venosus were measured before and after tocolysis.

Results:

There were no differences between the groups in terms of maternal age, gestational week, body mass indexes, cervical dilation, effacement at admission, birth weights and latency periods until birth. Nifedipine decreased resistance indexes in uterine arteries but magnesium sulfate increased resistance especially in the right uterine artery. Nifedipine significantly decreased systole to diastole and resistance index in the umbilical artery, magnesium sulfate increased systole to diastole and resistance index but this was not statistically significant. Nifedipine acted variably on resistance index and pulsatility index in the ductus venosus; however, magnesium sulfate increased resistance. Nifedipine decreased pulsatility index in the middle cerebral artery, contrary to magnesium sulfate with which it increased.

Conclusion:

Nifedipine had favorable effects on maternal and fetal vessel indexes but magnesium sulfate increased resistance. Despite the proposed neuroprotective benefits of magnesium sulfate, nifedipine seems to be a better and safer tocolytic agent than magnesium sulfate due to its positive beneficial effects on maternal and fetal vessels.

Nifedipine versus atosiban for threatened preterm birth (APOSTEL III): a multicentre, randomised controlled trial

BACKGROUND

In women with threatened preterm birth, delay of delivery by 48 h allows antenatal corticosteroids to improve neonatal outcomes. For this reason, tocolytics are often administered for 48 h; however, there is no consensus about which drug results in the best maternal and neonatal outcomes. In the APOSTEL III trial we aimed to compare the effectiveness and safety of the calcium-channel blocker nifedipine and the oxytocin inhibitor atosiban in women with threatened preterm birth.

METHODS

We did this multicentre, randomised controlled trial in ten tertiary and nine teaching hospitals in the Netherlands and Belgium. Women with threatened preterm birth (gestational age 25-34 weeks) were randomly assigned (1:1) to either oral nifedipine or intravenous atosiban for 48 h. An independent data manager used a web-based computerised programme to randomly assign women in permuted block sizes of four, with groups stratified by centre. Clinicians, outcome assessors, and women were not masked to treatment group. The primary outcome was a composite of adverse perinatal outcomes, which included perinatal mortality, bronchopulmonary dysplasia, sepsis, intraventricular haemorrhage, periventricular leukomalacia, and necrotising enterocolitis. Analysis was done in all women and babies with follow-up data. The study is registered at the Dutch Clinical Trial Registry, number NTR2947.

FINDINGS

Between July 6, 2011, and July 7, 2014, we randomly assigned 254 women to nifedipine and 256 to atosiban. Primary outcome data were available for 248 women and 297 babies in the nifedipine group and 255 women and 294 babies in the atosiban group. The primary outcome occurred in 42 babies (14%) in the nifedipine group and in 45 (15%) in the atosiban group (relative risk [RR] 0·91, 95% CI 0·61-1·37). 16 (5%) babies died in the nifedipine group and seven (2%) died in the atosiban group (RR 2·20, 95% CI 0·91-5·33); all deaths were deemed unlikely to be related to the study drug. Maternal adverse events did not differ between groups.

INTERPRETATION

In women with threatened preterm birth, 48 h of tocolysis with nifedipine or atosiban results in similar perinatal outcomes. Future clinical research should focus on large placebo-controlled trials, powered for perinatal outcomes.

FUNDING

ZonMw (the Netherlands Organisation for Health Research and Development).

Maternal and fetal haemodynamic effects of nifedipine in normotensive pregnant women

While nifedipine is commonly used for tocolysis, the controversy on its safety remains. So far, the haemodynamic effects on maternal and fetal circulations have not been well documented. Fifteen normotensive women who received 20 mg nifedipine were included in this prospective observational study. The maternal and fetal haemodynamic effects were analysed using maternal echocardiography and fetal Doppler ultrasonography. Nifedipine induced a significant afterload reduction in all women. It triggered a compensatory increase in cardiac output, which maintained blood pressure. These maternal changes had no influence on the uteroplacental and fetal circulations.

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.

The effect of nifedipine tocolysis on Doppler indices of the uterine and umbilical arteries

PURPOSE

The aim of this study was to evaluate the effect of oral nifedipine on Doppler indices of the uterine artery (UtA) and umbilical artery (UA) before and 24 hours, 48 hours, and 1 week after tocolytic treatment.

METHODS

This was a prospective, self-controlled, cohort study of 65 pregnant women undergoing nifedipine tocolysis. Doppler assessment of the UtA and UA was performed before treatment and 24 hours, 48 hours, and 1 week after the initial 4 doses of 10 mg of oral nifedipine, administered at 20-minute intervals. The maintenance dosage was 20 mg of oral nifedipine administered every 6 hours for 48 hours, for a total dose of 80 mg/day.

RESULTS

There was a decrease in the 24-hour values of the UA pulsatility index, resistance index (RI), systolic-diastolic (S:D) ratio, right UtA pulsatility index, RI, S:D ratio, and left UtA RI and S:D ratio with nifedipine therapy in comparison with the values recorded prior to nifedipine therapy. However, these differences were not statistically significant. There were no statistically significant differences between the data recorded prior to nifedipine administration and those obtained at 48 hours and 1 week after treatment.

CONCLUSIONS

Oral nifedipine is a safe tocolytic agent with no long-term effect on fetomaternal circulation in pregnant women at risk of preterm delivery.

Calcium channel blockers for inhibiting preterm labour and birth

BACKGROUND

Preterm birth is a major contributor to perinatal mortality and morbidity, affecting around 9% of births in high-income countries and an estimated 13% of births in low- and middle-income countries. Tocolytics are drugs used to suppress uterine contractions for women in preterm labour. The most widely used tocolytic are the betamimetics, however, these are associated with a high frequency of unpleasant and sometimes severe maternal side effects. Calcium channel blockers (CCBs) (such as nifedipine) may have similar tocolytic efficacy with less side effects than betamimetics. Oxytocin receptor antagonists (ORAs) (e.g. atosiban) also have a low side-effect profile.

OBJECTIVES

To assess the effects on maternal, fetal and neonatal outcomes of CCBs, administered as a tocolytic agent, to women in preterm labour.

SEARCH METHODS

We searched the Cochrane Pregnancy and Childbirth Group's Trials Register (12 November 2013).

SELECTION CRITERIA

All published and unpublished randomised trials in which CCBs were used for tocolysis for women in labour between 20 and 36 completed weeks' gestation.

DATA COLLECTION AND ANALYSIS

Two review authors independently assessed trial eligibility, undertook quality assessment and data extraction. Results are presented using risk ratio (RR) for categorical data and mean difference (MD) for data measured on a continuous scale with the 95% confidence interval (CI). The number needed to treat to benefit (NNTB) and the number needed to treat to harm (NNTH) were calculated for categorical outcomes that were statistically significantly different.

MAIN RESULTS

This update includes 26 additional trials involving 2511 women, giving a total of 38 included trials (3550 women). Thirty-five trials used nifedipine as the CCB and three trials used nicardipine. Blinding of intervention and outcome assessment was undertaken in only one of the trials (a placebo controlled trial). However, objective outcomes defined according to timing of birth and perinatal mortality were considered to have low risk of detection bias.Two small trials comparing CCBs with placebo or no treatment showed a significant reduction in birth less than 48 hours after trial entry (RR 0.30, 95% CI 0.21 to 0.43) and an increase in maternal adverse effects (RR 49.89, 95% CI 3.13 to 795.02, one trial of 89 women). Due to substantial heterogeneity, outcome data for preterm birth (less than 37 weeks) were not combined; one placebo controlled trial showed no difference (RR 0.96, 95% CI 0.89 to 1.03) while the other (non-placebo controlled trial) reported a reduction (RR 0.44, 95% CI 0.31 to 0.62). No other outcomes were reported.Comparing CCBs (mainly nifedipine) with other tocolytics by type (including betamimetics, glyceryl trinitrate (GTN) patch, non-steriodal anti inflammatories (NSAID), magnesium sulphate and ORAs), no significant reductions were shown in primary outcome measures of birth within 48 hours of treatment or perinatal mortality.Comparing CCBs with betamimetics, there were fewer maternal adverse effects (average RR 0.36, 95% CI 0.24 to 0.53) and fewer maternal adverse effects requiring discontinuation of therapy (average RR 0.22, 95% CI 0.10 to 0.48). Calcium channel blockers resulted in an increase in the interval between trial entry and birth (average MD 4.38 days, 95% CI 0.25 to 8.52) and gestational age (MD 0.71 weeks, 95% CI 0.34 to 1.09), while decreasing preterm and very preterm birth (RR 0.89, 95% CI 0.80 to 0.98 and RR 0.78, 95% CI 0.66 to 0.93); respiratory distress syndrome (RR 0.64, 95% CI 0.48 to 0.86); necrotising enterocolitis (RR 0.21, 95% CI 0.05 to 0.96); intraventricular haemorrhage (RR 0.53, 95% CI 0.34 to 0.84); neonatal jaundice (RR 0.72, 95% CI 0.57 to 0.92); and admissions to neonatal intensive care unit (NICU) (average RR 0.74, 95% CI 0.63 to 0.87). No difference was shown in one trial of outcomes at nine to twelve years of age.Comparing CCBs with ORA, data from one study (which did blind the intervention) showed an increase in gestational age at birth (MD 1.20 completed weeks, 95% CI 0.25 to 2.15) and reductions in preterm birth (RR 0.64, 95% CI 0.47 to 0.89); admissions to the NICU (RR 0.59, 95% CI 0.41 to 0.85); and duration of stay in the NICU (MD -5.40 days,95% CI -10.84 to 0.04). Maternal adverse effects were increased in the CCB group (average RR 2.61, 95% CI 1.43 to 4.74).Comparing CCBs with magnesium sulphate, maternal adverse effects were reduced (average RR 0.52, 95% CI 0.40 to 0.68), as was duration of stay in the NICU (days) (MD -4.55, 95% CI -8.17 to -0.92). No differences were shown in the comparisons with GTN patch or NSAID, although numbers were small.No differences in outcomes were shown in trials comparing nicardipine with other tocolytics, although with limited data no strong conclusions can be drawn. No differences were evident in a small trial that compared higher- versus lower-dose nifedipine, though findings tended to favour a high dose on some measures of neonatal morbidity.

AUTHORS' CONCLUSIONS

Calcium channel blockers (mainly nifedipine) for women in preterm labour have benefits over placebo or no treatment in terms of postponement of birth thus, theoretically, allowing time for administration of antenatal corticosteroids and transfer to higher level care. Calcium channel blockers were shown to have benefits over betamimetics with respect to prolongation of pregnancy, serious neonatal morbidity, and maternal adverse effects. Calcium channel blockers may also have some benefits over ORAs and magnesium sulphate, although ORAs results in fewer maternal adverse effects. However, it must be noted that no difference was shown in perinatal mortality, and data on longer-term outcomes were limited. Further, the lack of blinding of the intervention diminishes the strength of this body of evidence. Further well-designed tocolytic trials are required to determine short- and longer-term infant benefit of CCBs over placebo or no treatment and other tocolytics, particularly ORAs. Another important focus for future trials is identifying optimal dosage regimens of different types of CCBs (high versus low, particularly addressing speed of onset of uterine quiescence) and formulation (capsules versus tablets). All future trials on tocolytics for women in preterm labour should employ blinding of the intervention and outcome assessment, include measurement of longer-term effects into early childhood, and also costs.

Beyond the placental bed: placental and systemic determinants of the uterine artery Doppler waveform

The uterine artery Doppler waveform has been extensively investigated, though its widespread clinical use as a predictor of adverse pregnancy outcome remains under debate. The determinants of the waveform have classically been ascribed to transformation of the spiral arteries and the development of a low resistance uteroplacental circulation, failure of which predisposes to pre-eclampsia, fetal growth restriction and other adverse outcomes. It has become increasingly evident that although spiral artery transformation determines in some part the characteristics of the Doppler waveform, factors pertaining to maternal vascular and endothelial function are also important.

Outcome of vaginal progesterone as a tocolytic agent: randomized clinical trial

Vaginal progesterone has a potential beneficial effect in postponing of preterm labor by suppression of prostaglandins cascades. Although different studies evaluated the use of progesterone for preterm birth, the exact effect of which on prolongation of pregnancy remains unclear. Seventy two women who underwent preterm labor were managed by magnesium sulfate. Then they were randomly assigned to continue pregnancy either by applying vaginal progesterone (400 mg) until delivery or without using any drug. Gestational age mean at the time of delivery (P = 0.039) and postponing delivery mean time (P = 0.048) were significantly higher in progesterone group. Comparison of neonatal outcomes between two groups of patients showed meaningful benefits of progesterone in increasing of neonatal weight, reduction of low birth weight babies, and lowing neonate admitted in NICU.

Antenatal calcium channel blocker exposure and subsequent patent ductus arteriosus in extremely low-birth-weight infants

This study aimed to assess whether tocolytic fetal exposure to antenatal calcium channel blockers (aCCB) increases the risk for hemodynamically significant patent ductus arteriosus (hsPDA) in extremely low-birth-weight (ELBW) infants. This case-control study investigated ELBW infants (<1,000 g) without cardiac defects in a level 3 neonatal intensive care unit who had survived at least 7 days. Nifedipine was the only aCCB used for this study population. The measurements included the history of aCCB exposure, selected maternal data, hsPDA diagnosis, gestational age at birth, birth weight, mode of delivery, sex, maternal race, location of birth, Apgar scores, and selected neonatal morbidities. The end point of the study was hsPDA, defined as an echocardiographically confirmed PDA with clinical symptoms. A total of 180 infants met the study criteria. The diagnosis was hsPDA for 56% of these patients, 20% of whom had aCCB exposure. Of the infants without hsPDA, 11% had aCCB exposure (p = 0.09). No statistically significant associations were found between aCCB exposure and hsPDA after adjustment for gestational age (odds ratio [OR], 1.5; 95% confidence interval [CI], 0.6-3.7) or for gestational age and cumulative aCCB exposure of 100 mg or more (OR, 2.0; 95% CI, 0.6-6.5). A history of aCCB exposure does not appear to increase hsPDA risk in ELBW infants. Studies using neonatal serum nifedipine concentrations after antenatal exposure should be performed to confirm this conclusion.

Management of preterm labor: atosiban or nifedipine?

Preterm birth is strongly associated with neonatal death and long-term neurological morbidity. The purpose of tocolytic drug administration is to postpone threatening preterm delivery for 48 hours to allow maximal effect of antenatal corticosteroids and maternal transportation to a center with specialized neonatal care facilities. There is uncertainty about the value of atosiban (oxytocin receptor antagonist) and nifedipine (calcium channel blocker) as first-line tocolytic drugs in the management of preterm labor. For nifedipine, concerns have been raised about unproven safety, lack of placebo-controlled trials, and its off-label use. The tocolytic efficacy of atosiban has also been questioned because of a lack of reduction in neonatal morbidity. This review discusses the available evidence, the pros and cons of either drug and aims to provide information to support a balanced choice of first-line tocolytic drug: atosiban or nifedipine?

Doppler velocimetry of the uterine, umbilical and fetal middle cerebral arteries in pregnant women undergoing tocolysis with oral nifedipine

OBJECTIVES

To evaluate Doppler velocimetry (resistance index (RI) and peak systolic velocity (PSV)) in the maternal-fetal circulation before and 5 and 24 h after tocolysis with oral nifedipine.

METHODS

This was a prospective, observational, analytic cohort study performed in 47 pregnant women undergoing nifedipine tocolysis, each subject acting as her own control. Doppler assessment of uterine, umbilical and fetal middle cerebral (MCA) arteries was performed before and 5 and 24 h after an initial 20-mg sublingual dose, which was repeated twice at 20-min intervals if contractions failed to diminish. The maintenance dose consisted of 20 mg orally every 6 h for 24 h up to a total of 100-120 mg nifedipine. We analyzed whether there was a time effect and compared values at the different time-points.

RESULTS

The MCA-RI had decreased significantly after 24 h of tocolysis (0 h = 0.85; 5 h = 0.85; 24 h = 0.81; P = 0.001), with no differences in uterine or umbilical arteries or in the MCA to umbilical artery ratio. The MCA-PSV had reduced significantly after 5 h (0 h = 41.5 cm/s; 5 h = 34.7 cm/s; P = 0.001), returning close to baseline levels between 5 and 24 h. The PSV increased significantly between 5 and 24 h in the right uterine artery (5 h = 55.1 cm/s; 24 h = 65.0 cm/s; P = 0.037) and in the umbilical artery (5 h = 28.4 cm/s; 24 h = 33.1 cm/s; P = 0.038).

CONCLUSIONS

Nifedipine tocolysis is associated with a reduction in RI in the MCA but not in the uterine or umbilical arteries, a reduction in PSV in the MCA after 5 h but returning to baseline within 24 h, and an increase in PSV between 5 and 24 h in the umbilical and right uterine arteries.

The effects of the tocolytics atosiban and nifedipine on fetal movements, heart rate and blood flow

BACKGROUND

The choice of first-line tocolytic agent is a topic of worldwide debate. The oxytocin receptor antagonist atosiban and the calcium antagonist nifedipine appear to be effective in postponing delivery. However, information is lacking on their possible effects on the fetal biophysical profile.

OBJECTIVE

To study the direct fetal effects of tocolysis with atosiban or nifedipine combined with a course of betamethasone.

METHOD

We performed a randomised controlled study including women with preterm labour requiring tocolytic treatment. Primary outcome measures were the effects on fetal heart rate (FHR) and its variation. Secondary endpoints were the effects on fetal movement and blood flow (pulsatility index - PI) of the umbilical (UA) and medial cerebral arteries (MCA).

RESULTS

One-hour recordings of FHR and fetal movements were made on each of five successive days (days 0-4). Fetal blood flow velocity patterns were studied daily by Doppler ultrasound. Baseline characteristics of 31 women who had not delivered at day 0 and needed no escape tocolysis did not differ between the study groups. Multilevel analysis showed no significant effect of either tocolytic on FHR and movement parameters over the 5-day study period. The use of tocolytics also did not significantly alter the time courses of PI-values for UA (p = 0.37) and MCA (p = 0.62).

CONCLUSION

This study demonstrates for the first time the direct effects of atosiban on fetal movement, heart rate and blood flow. Tocolysis with either atosiban or nifedipine combined with betamethasone administration appears to have no direct fetal adverse effects.

Major sacrococcygeal teratoma in an extreme premature infant: a multidisciplinary approach

Antenatally diagnosed, large sacrococcygeal teratomas in very premature infants are associated with a very poor outcome. We present an extreme premature infant with cardiac decompensation, diagnosed at 27 weeks and 1 day of gestational age. A positive outcome could be achieved with intensive multidisciplinary planning of the delivery, postnatal stabilization and surgical resection, as demonstrated in this case report.

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.