The effect of magnesium sulfate on fetal heart rate parameters: A randomized, placebo-controlled trial

Association between marked fetal heart rate variability and neonatal acidosis: A prospective cohort study

OBJECTIVE

To assess the association between marked variability in fetal heart rate (FHR) and neonatal acidosis.

DESIGN

Bicentric prospective cohort study.

SETTING

From January 2019 to December 2019, in two French tertiary care maternity units.

POPULATION

Women in labour at ≥37 weeks of gestation, with continuous FHR monitoring until delivery and with the availability of umbilical arterial pH. Women with intrauterine fetal death or medical termination, multiple pregnancies, non-cephalic presentation or planned caesarean delivery were excluded.

METHODS

The exposure was marked variability in FHR in the 60 minutes before delivery, defined as a variability greater than 25 beats per minute, with a minimum duration of 1 minute. To assess the association between marked variability and neonatal acidosis, we used multivariable modified Poisson regression modelling. We then conducted subgroup analyses according to the US National Institute of Child Health and Human Development (NICHD) category of the associated fetal heart rate.

MAIN OUTCOME MEASURES

Neonatal acidosis, defined as an umbilical artery pH of ≤7.10.

RESULTS

Among the 4394 women included, 177 (4%) had marked variability in fetal heart rate in the 60 minutes before delivery. Acidosis occurred in 6.0% (265/4394) of the neonates. In the multivariable analysis, marked variability was significantly associated with neonatal acidosis (aRR 2.30, 95% CI 1.53-3.44). In subgroup analyses, the association between marked variability and neonatal acidosis remained significant in NICHD category-I and category-II groups.

CONCLUSIONS

Marked variability was associated with a twofold increased risk of neonatal acidosis.

Update on Fetal Monitoring: Overview of Approaches and Management of Category II Tracings

Electronic fetal monitoring (EFM) is widely used to assess fetal status in labor. Use of intrapartum continuous EFM is associated with a lower risk of neonatal seizures but a higher risk of cesarean or operative delivery. Category II fetal heart tracings (FHTs) are indeterminate in their ability to predict fetal acidemia. Certain patterns of decelerations and variability within this category may be predictive of neonatal morbidity. Adjunct tests of fetal well-being can be used during labor to further triage patients. Intrauterine resuscitation techniques should target the suspected etiology of intrapartum fetal hypoxia. Clinical factors play a role in the interpretation of EFM.

Effect of tocolytic drugs on fetal heart rate variability: a systematic review

INTRODUCTION

Tocolytics may cause changes in fetal heart rate (HR) pattern, while fetal heart rate variability (HRV) is an important marker of fetal well-being. We aim to systematically review the literature on how tocolytic drugs affect fetal HRV.

MATERIALS AND METHODS

We searched CENTRAL, PubMed and EMBASE up to June 2016. Studies published in English, using computerized or visual analysis to describe the effect of tocolytics on HRV in human fetuses were included. Studies describing tocolytics during labor, external cephalic version, pre-eclampsia and infection were excluded. Eventually, we included six studies, describing 169 pregnant women.

RESULTS

Nifedipine, atosiban and indomethacin administration show no clinically important effect on fetal HRV. Following administration of magnesium sulfate decreased variability and cases of bradycardia are described. Fenoterol administration results in a slight increase in fetal HR with no changes in variability. After ritodrine administration increased fetal HR and decreased variability is seen. The effect of co-administration of corticosteroids should be taken into account.

CONCLUSION

In order to prevent iatrogenic preterm labor, the effects of tocolytic drugs on fetal HRV should be taken into account when monitoring these fetuses.

Magnesium supplementation in pregnancy

BACKGROUND

Magnesium is an essential mineral required for regulation of body temperature, nucleic acid and protein synthesis and in maintaining nerve and muscle cell electrical potentials. Many women, especially those from disadvantaged backgrounds, have low intakes of magnesium. Magnesium supplementation during pregnancy may be able to reduce fetal growth restriction and pre-eclampsia, and increase birthweight.

OBJECTIVES

To assess the effects of magnesium supplementation during pregnancy on maternal, neonatal/infant and paediatric outcomes.

SEARCH METHODS

We searched the Cochrane Pregnancy and Childbirth Group's Trials Register (31 March 2013).

SELECTION CRITERIA

Randomised and quasi-randomised trials assessing the effects of dietary magnesium supplementation during pregnancy were included. The primary outcomes were perinatal mortality (including stillbirth and neonatal death prior to hospital discharge), small-for-gestational age, maternal mortality and pre-eclampsia.

DATA COLLECTION AND ANALYSIS

Two review authors independently assessed study eligibility, extracted data and assessed the risk of bias of included studies.

MAIN RESULTS

Ten trials involving 9090 women and their babies were included; one trial had a cluster design (with randomisation by study centre). All 10 trials randomly allocated women to either an oral magnesium supplement or a control group; in eight trials a placebo was used, and in two trials no treatment was given to the control group. In the 10 included trials, the compositions of the magnesium supplements, gestational ages at commencement, and doses administered varied, including: magnesium oxide, 1000 mg daily from ≤ four months post-conception (one trial); magnesium citrate, 365 mg daily from ≤ 18 weeks until hospitalisation after 38 weeks (one trial), and 340 mg daily from nine to 27 weeks' gestation (one trial); magnesium gluconate, 2 to 3 g from 28 weeks' gestation until birth (one trial), and 4 g daily from 23 weeks' gestation (one trial); magnesium aspartate, 15 mmol daily (three trials, commencing from either six to 21 weeks' gestation until birth, ≤ 16 weeks' gestation until birth, or < 12 weeks until birth), or 365 mg daily from 13 to 24 weeks until birth (one trial); and magnesium stearate, 128 mg elemental magnesium from 10 to 35 weeks until birth (one trial).In the analysis of all trials, oral magnesium supplementation compared to no magnesium was associated with no significant difference in perinatal mortality (stillbirth and neonatal death prior to discharge) (risk ratio (RR) 1.10; 95% confidence interval (CI) 0.72 to 1.67; five trials, 5903 infants), small-for-gestational age (RR 0.76; 95% CI 0.54 to 1.07; three trials, 1291 infants), or pre-eclampsia (RR 0.87; 95% CI 0.58 to 1.32; three trials, 1042 women). None of the included trials reported on maternal mortality.Considering secondary outcomes, while no increased risk of stillbirth was observed, a possible increased risk of neonatal death prior to hospital discharge was shown for infants born to mothers who had received magnesium (RR 2.21; 95% CI 1.02 to 4.75; four trials, 5373 infants). One trial contributed over 70% of the participants to the analysis for this outcome; the trial authors suggested that the large number of severe congenital anomalies in the supplemented group (unlikely attributable to magnesium) and the deaths of two sets of twins (with birthweights < 750 g) in the supplemented group likely accounted for the increased risk of death observed, and thus this result should be interpreted with caution. Furthermore, when the deaths due to severe congenital abnormalities in this trial were excluded from the meta-analysis, no increased risk of neonatal death was seen for the magnesium supplemented group. Magnesium supplementation was associated with significantly fewer babies with an Apgar score less than seven at five minutes (RR 0.34; 95% CI 0.15 to 0.80; four trials, 1083 infants), with meconium-stained liquor (RR 0.79; 95% CI 0.63 to 0.99; one trial, 4082 infants), late fetal heart decelerations (RR 0.68; 95% CI 0.53 to 0.88; one trial, 4082 infants), and mild hypoxic-ischaemic encephalopathy (RR 0.38; 95% CI 0.15 to 0.98; one trial, 4082 infants). Women receiving magnesium were significantly less likely to require hospitalisation during pregnancy (RR 0.65, 95% CI 0.48 to 0.86; three trials, 1158 women).Of the 10 trials included in the review, only two were judged to be of high quality overall. When an analysis was restricted to these two trials none of the review's primary outcomes (perinatal mortality, small-for-gestational age, pre-eclampsia) were significantly different between the magnesium supplemented and control groups.

AUTHORS' CONCLUSIONS

There is not enough high-quality evidence to show that dietary magnesium supplementation during pregnancy is beneficial.

Identification, assessment and management of fetal compromise

The main goals of fetal surveillance are to avoid fetal death and to recognize the fetus that will benefit from early intervention with resuscitation or delivery. Surveillance can occur in the antepartum or intrapartum period. Continuous fetal heart rate monitoring is the most common form of surveillance in the intrapartum period. Several techniques are used in the antepartum period, including nonstress test, biophysical profile, and contraction stress test. Multiple techniques are used once distress is noted in the fetus, with the ultimate resuscitation effort being delivery.

Effect of magnesium sulfate on fetal heart rate patterns in the second stage of labor

OBJECTIVE

To estimate the effect of maternal exposure to magnesium sulfate on fetal heart rate characteristics during active labor.

METHODS

Within a 4-year retrospective cohort study of consecutive term deliveries reaching the second stage of labor, we compared women exposed to magnesium for severe preeclampsia to all women not exposed. Primary outcome was the electronic fetal monitoring tracing in the 30 minutes preceding delivery. Secondary outcomes were fetal acidemia and nursery disposition. Attributable risk estimates and multivariable logistic regression were used to estimate the association between magnesium exposure and fetal heart rate characteristics. Unadjusted risk estimates for the association between fetal heart rate characteristics and neonatal outcomes were generated stratified by group.

RESULTS

Of 5,387 women, 248 (4.6%) were exposed to magnesium. Magnesium exposure was associated with lower fetal heart rate baseline (136.9 ± 12.3 beats per minute compared with 139.0 ± 13.5 beats per minute; P=.02), increased risk of baseline less than 120 beats per minute (adjusted odds ratio [OR] 1.76, 95% confidence interval [CI] 1.21-2.56), and increased risk of absent or minimal variability (adjusted OR 2.41, 95% CI 1.78-3.27). More than 20% increased frequency of ever absent or minimal variability was attributable to magnesium (attributable risk 0.21, 95% CI 0.15-0.27). There were no significant differences in presence or number of accelerations or decelerations; however, magnesium was associated with fewer prolonged decelerations (adjusted OR 0.64, 95% CI 0.49-0.84). After excluding women with adverse neonatal outcomes, these associations remained.

CONCLUSION

Maternal exposure to magnesium is associated with lower fetal heart rate baseline within the accepted normal range, decreased variability, and fewer prolonged decelerations without evidence of adverse effect on neonatal outcome.

LEVEL OF EVIDENCE

II.

Effect of small for gestational age on hemodynamic parameters in the neonatal period

OBJECTIVE

The time course over which hypertension develops in children with a history of growth restriction has not been fully elucidated. The purpose of this study was to determine whether commonly obtained hemodynamic parameters were different between small for gestational age (SGA) and appropriate for gestational age (AGA) neonates.

METHODS

This was a retrospective case-control study matching 24 SGA neonates in a 1:2 fashion with 48 AGA neonates delivered during the same gestational week. Hemodynamic parameters were evaluated during the first week of life and the week prior to discharge.

RESULTS

There were no differences in blood pressure (BP) parameters during the first week of life. Compared to AGA controls, SGA neonates had a significantly lower heart rate (HR) at birth (148.2 ± 19.2 vs. 159.2 ± 17.1, p < 0.001), and a greater need for vasopressor support (OR 5.66; 95% CI 2.28, 14.04). The SGA neonates had a lower systolic BP during the week prior to discharge (68.3 ± 1.2 vs. 73.5 ± 1.2 mmHg, p < 0.001).

CONCLUSIONS

SGA newborns had a lower HR at birth and greater need for vasopressor support during the first week of life despite similar BP parameters. SGA newborns had a lower systolic BP prior to discharge. Further studies are needed to understand the progression to adult hypertension.

Nutritional and exercise-based interventions in the treatment of amyotrophic lateral sclerosis

BACKGROUND & AIMS

Disease pathogenesis in amyotrophic lateral sclerosis (ALS) involves a number of interconnected mechanisms all resulting in the rapid deterioration of motor neurons. The main mechanisms include enhanced free radical production, protein misfolding, aberrant protein aggregation, excitotoxicity, mitochondrial dysfunction, neuroinflammation and apoptosis. The aim of this review is to assess the efficacy of using nutrition- and exercise-related interventions to improve disease outcomes in ALS.

METHODS

Studies involving nutrition or exercise in human and animal models of ALS were reviewed.

RESULTS

Treatments conducted in animal models of ALS have not consistently translated into beneficial results in clinical trials due to poor design, lack of power and short study duration, as well as differences in the genetic backgrounds, treatment dosages and disease pathology between animals and humans. However, vitamin E, folic acid, alpha lipoic acid, lyophilized red wine, coenzyme Q10, epigallocatechin gallate, Ginkgo biloba, melatonin, Cu chelators, and regular low and moderate intensity exercise, as well as treatments with catalase and l-carnitine, hold promise to mitigating the effects of ALS, whereas caloric restriction, malnutrition and high-intensity exercise are contraindicated in this disease model.

CONCLUSIONS

Improved nutritional status is of utmost importance in mitigating the detrimental effects of ALS.

Intrapartum fetal monitoring today

The literature on intrapartum fetal monitoring is reviewed emphasizing the pathophysiology, and current practice guidelines are discussed. FHR monitoring, ancillary tests, and investigational modalities are considered.

Management options for preterm labour in Canada

OBJECTIVES

(1) To determine the current use of treatment options for preterm labour and (2) to review the relative safety and efficacy of each class of tocolytic agent.

METHODS

MEDLINE and the Cochrane Library were searched using the terms "preterm delivery," "preterm labour," and "tocolysis" alone, and in combination with the terms "betamimetics," "ritodrine," "magnesium sulfate," "calcium channel blockers," "nifedipine," "prostaglandin synthetase inhibitors," "indomethacin," "glyceryl trinitrate," "nitroglycerin," "oxytocin antagonists," and "atosiban." Randomized controlled trials (RCTs) that compared the effect of a tocolytic with a placebo or other tocolytic in women with preterm labour were selected. Trials were assessed according to Jadad's validated quality scale for assessing the quality of RCTs. Thirty two RCTs retrieved met the inclusion criteria. Information not evident from RCTs was sought from non-randomized clinical trials, cohort studies, case control studies, case series, and case reports. Data from the Canadian Survey on Tocolytic Use was obtained directly from the Society of Obstetricians and Gynaecologists of Canada (SOGC).

RESULTS

The available evidence on the use of tocolytics to prolong pregnancy fails to show benefits in neonatal survival and reduced disability. This uncertainty of benefit makes the issue of fetal and maternal drug toxicity more important. There is great concern among SOGC members over the lack of effective and safe treatment options for the management of preterm labour.

CONCLUSIONS

Further well-designed placebo-controlled trials are necessary to study the efficacy and safety of tocolytics in managing preterm labour.

The effect of intrapartum magnesium sulfate therapy on fetal cardiac troponin I levels at delivery

OBJECTIVE

To determine whether intrapartum magnesium sulfate (MgSO4) therapy for seizure prophylaxis in pre-eclampsia-eclampsia is associated with biochemical evidence of subacute fetal myocardial damage at delivery.

STUDY DESIGN

Troponin I, a cardiac-specific protein used to detect myocardial injury, was measured from the umbilical vein at delivery in term pregnancies complicated by pre-eclampsia and uncomplicated control pregnancies. Women with pre-eclampsia received intravenous MgSO4 as a 6-g load followed by 2 g/hour until delivery. Clinical characteristics and fetal troponin levels were compared between groups.

RESULTS

There was no difference in troponin I concentrations between term patients with intrapartum MgSO4 therapy and controls who did not receive MgSO4 (median 0.86 ng/ml, range 0.72-1.10 vs. 0.89 ng/ml, range 0.68-1.50; p = 1.0). There was also no statistically significant difference in the number of patients with a troponin I level of > or = 1.0 ng/ml between groups (30.8% (4/13) vs. 15.4% (4/26); p = 0.4).

CONCLUSIONS

Our findings suggest that, in term fetuses that are not growth impaired, exposure to intrapartum MgSO4 is not associated with subacute myocardial injury.

Advances in prevention and treatment of cerebral palsy

In recent years there have been a number of advances in understanding of predisposing and protective factors in the development of cerebral palsy in infants. Multiple gestation births, maternal infection, and maternal and fetal thrombophilic conditions all predispose to the development of CP in the infant. Opportunities for prevention of CP may develop from an improved understanding of these factors and their mechanisms of operation. Similar progress has been made in the evaluation of treatments for CP and the effects of these treatments on the individual's impairment, function, and disability. Selective posterior rhizotomy and Botulinum toxin A are now widely used in the treatment of spasticity. The challenge remains to determine how effectively these promising interventions can alter long-term function and quality of life outcomes in children and adults with CP.

Magnesium supplementation in pregnancy

BACKGROUND

Many women, especially those from disadvantaged backgrounds, have intakes of magnesium below recommended levels. Magnesium supplementation during pregnancy may be able to reduce fetal growth retardation and pre-eclampsia, and increase birthweight.

OBJECTIVES

The objective of this review was to assess the effects of magnesium supplementation during pregnancy on maternal, neonatal and paediatric outcomes.

SEARCH STRATEGY

We searched the Cochrane Pregnancy and Childbirth Group trials register.

SELECTION CRITERIA

Randomised and quasi-randomised trials of dietary magnesium supplementation during pregnancy.

DATA COLLECTION AND ANALYSIS

Suitability for inclusion and methodological quality were separately assessed by each reviewer. Data were independently extracted by two reviewers.

MAIN RESULTS

Six trials involving 2637 women were included. Only one of these trials was judged to be of high quality. Compared with placebo, oral magnesium treatment from before the 25th week of gestation was associated with a lower incidence of preterm birth (odds ratio 0.71, 95% confidence interval 0.52 to 0.95). There was also less maternal hospitalisation during pregnancy, fewer cases of antepartum haemorrhage, a lower incidence of low birthweight and small for gestational age infants. Poor quality trials are likely to have resulted in a bias favouring magnesium supplementation.

REVIEWER'S CONCLUSIONS

There is not enough high quality evidence to show that dietary magnesium supplementation during pregnancy is beneficial.