Magnesium sulfate and neonatal outcomes of preterm neonates

Maternal and neonatal outcomes following magnesium sulfate in the setting of chorioamnionitis: a meta-analysis

PURPOSE

Magnesium sulfate (MgSO4) has been widely used in obstetrics as a mean to help decrease maternal and neonatal morbidity in various antenatal pathology. As a factor, it seems to regulate immunity and can, thus, predispose to infectious morbidity. To date, it remains unknown if its administration can increase the risk of chorioamnionitis. In the present meta-analysis, we sought to accumulate the available evidence.

METHODS

We systematically searched Medline, Scopus, Clinicaltrials.gov, EMBASE, Cochrane Central Register of Controlled Trials CENTRAL, and Google Scholar databases in our primary search along with the reference lists of electronically retrieved full-text papers.

RESULTS

Eight studies were included that investigated the incidence of chorioamnionitis among parturient that received MgSO4 and control patients. Magnesium sulfate was administered in 3229 women and 3330 women served as controls as they did not receive MgSO4. The meta-analysis of data revealed that there was no association between the administration of magnesium sulfate and the incidence of chorioamnionitis (OR 0.98, 95% CI 0.73, 1.32). Rucker's analysis revealed that small studies did not significantly influence the statistical significance of this finding (OR 1.12, 95% CI 0.82, 1.53). Trial sequential analysis revealed that the required number to safely interpret the primary outcome was not reached. Two studies evaluated the impact of MgSO4 in neonates delivered in the setting of chorioamnionitis. Neither of these indicated the presence of a beneficial effect in neonatal morbidity, including the risk of cerebral palsy, intraventricular hemorrhage, necrotizing enterocolitis, bronchopulmonary dysplasia, sepsis, stillbirth, or neonatal death.

CONCLUSION

Current evidence indicates that magnesium sulfate is not associated with an increased risk of maternal chorioamnionitis. However, it should be noted that its effect on neonatal outcomes of offspring born in the setting of chorioamnionitis might be subtle if any, although the available evidence is very limited.

Antenatal Magnesium Sulfate and adverse gastrointestinal outcomes in Preterm infants-a systematic review and meta-analysis

INTRODUCTION

To evaluate the effect of antenatal magnesium sulfate (MgSO4) on mortality and morbidity outcomes related to the gastrointestinal system (GI) in preterm infants.

METHODS

Data sources: A systematic literature search was conducted in November 2022. PubMed, CINAHL Plus with Full Text (EBSCOhost), Embase (Elsevier), and CENTRAL (Ovid) were searched. There were 6695 references. After deduplication, 4332 remained. Ninety-nine full-text articles were assessed and forty four articles were included in the final analysis.

STUDY ELIGIBILITY CRITERIA

Randomized or quasi-randomized clinical trials and observational studies that evaluated at least one of the pre-specified outcomes were included. Preterm infants whose mothers were given antenatal MgSO4 were included and whose mothers did not receive antenatal MgSO4 were the comparators. The main outcomes and measures were: Necrotizing enterocolitis (NEC) (stage ≥ 2), surgical NEC, spontaneous intestinal perforation (SIP), feeding intolerance, time to reach full feeds, and GI-associated mortality.

STUDY APPRAISAL AND SYNTHESIS METHODS

A random-effects model meta-analysis was performed to yield pooled OR and its 95% CI for each outcome due to expected heterogeneity in the studies. The analysis for each predefined outcome was performed separately for adjusted and unadjusted comparisons. All included studies were assessed for methodological quality. The risk of bias was assessed using elements of the Cochrane Collaboration's tool 2.0 and the Newcastle-Ottawa Scale for randomized controlled trials (RCTs) and non-randomized studies (NRS), respectively. The study findings were reported as per PRISMA guidelines.

RESULTS

A total of thirty-eight NRS and six RCTs involving 51,466 preterm infants were included in the final analysis. There were no increased odds of stage ≥2 NEC, (NRS : n = 45,524, OR: 0.95; 95% CI: 0.84-1.08, I2- 5% & RCT's: n = 5205 OR: 1.00; 95% CI: 0.89-1.12, I2- 0%), SIP (n = 34,186, OR: 1.22, 95% CI: 0.94-1.58, I2-30%), feeding intolerance (n = 414, OR: 1.06, 95% CI: 0.64-1.76, I2-12%) in infants exposed to antenatal MgSO4. On the contrary, the incidence of surgical NEC was significantly lower in MgSO4 exposure infants (n = 29,506 OR:0.74; 95% CI: 0.62-0.90, ARR: 0.47%). Studies assessing the effect on GI-related mortality were limited to make any conceivable conclusion. The certainty of evidence (CoE) for all outcomes was adjudged as 'very low' as per GRADE.

CONCLUSION

Antenatal magnesium sulfate did not increase the incidence of gastrointestinal-related morbidities or mortality in preterm infants. With the current evidence concerns, regarding the adverse effects of MgSO4 administration leading to NEC/SIP or GI-related mortality in preterm infants should not be a hurdle in its routine use in antenatal mothers.

Protective factors against preterm infants to develop significant patent ductus arteriosus

BACKGROUND

Identifying preterm infants with a higher likelihood of spontaneous patent ductus arteriosus (PDA) closure would be desirable. This study aimed to examine daily PDA status during the first week of life for very low birthweight (VLBW, <1500 g) preterm infants and to develop a scoring system to predict spontaneous PDA closure.

METHODS

We enrolled VLBW infants admitted between January 2016 and January 2017 and performed daily echocardiographic screening for PDA existence. Oxygen index (OI, mean airway pressure × fraction of inspired oxygen/partial pressure of arterial oxygen) was applied to represent the respiratory condition.

RESULTS

A total of 215 VLBW infants were enrolled, and the accumulative incidence of spontaneous PDA closure by age 1 week was 80%, 70%, and 34% for infants born of gestational age (GA) ≥30, 28-29, and ≤27 weeks, respectively. Of these 215 infants, 184 infants entered the second phase to establish the scoring system. Infants with spontaneous PDA closure were more mature (GA 29.2 ± 2.3 vs. 26.9 ± 2.3 weeks, p < 0.001), had lower OI (2.8 ± 2.2 vs. 5.6 ± 5.3, p < 0.001) and were less likely to need endotracheal intubation (23% vs. 68%, p < 0.001). Using the receiver operating characteristics curve, OI <2.5 was determined favoring higher PDA closure incidence. The score was calculated based on the odds ratio generated in multiple regression: 4, 3 and 1 points for GA ≥30, 28-29 and ≤27 weeks, 2 and 1 points for OI <2.5 and ≥2.5, and 3 and 1 points for without and with endotracheal intubation. Using score ≥6 to predict PDA closure, the sensitivity and specificity were 0.77 and 0.72.

CONCLUSION

A score made up of GA, OI and need for intubation was proposed to predict spontaneous PDA closure by age 1 week, which could be helpful to clinicians in the management of PDA in preterm infants.

Effects of Antenatal Magnesium Sulfate on the Gut Function of Preterm (<32 weeks) Very Low Birth Weight Neonates: Experience from a Tertiary Institute in South India

OBJECTIVE

Antenatal magnesium sulfate (MgSO4) is found to have various adverse effects in newborn, but the effect on preterm gut is still unclear. This study aimed to evaluate the effects of antenatal MgSO4 on preterm gut function by assessing the clinical outcomes and mesenteric blood flow.

METHODS

This was a prospective cohort study on all preterm very low birth weight (VLBW) neonates born at a tertiary care center in South India from November 2016 to August 2017. Neonates with antenatal magnesium (Mg) exposure were compared with those with no exposure for various neonatal outcome variables like time to reach full feeds, feed intolerance, necrotizing enterocolitis (NEC) and other preterm complications, serial serum Mg levels and superior mesenteric artery (SMA) Doppler velocity measurements at two time points (24-48 h and 4-5 days after birth).

RESULTS

Out of 84 neonates, 56 neonates were exposed to antenatal Mg with a median cumulative maternal dose of 28 g and the rest 28 neonates had no exposure. The mean time to reach full feeds was the same in both groups (10.5 days). Feed intolerance episodes were similar in the first week of life between the exposed and unexposed groups (48.2% vs. 46.4%; p = 0.88). Univariate analysis revealed no difference between groups concerning rates of NEC (p = 0.17) or mortality (p = 0.39). There was no significant difference in SMA Doppler parameters and hypermagnesemia between the two groups.

CONCLUSION

Our study found no significant impact on postnatal feed tolerance and mesenteric blood flow among preterm VLBW neonates with antenatal MgSO4 exposure.

The effect of antenatal magnesium sulfate on intraventricular hemorrhage in premature infants: a systematic review and meta-analysis

OBJECTIVE

The aim of this systematic review and meta-analysis study was to determine the pooled estimate of the effect of antenatal magnesium sulfate (MgSO4) on intraventricular hemorrhage (IVH) in premature infants.

METHODS

Two review authors independently searched all randomized clinical trials from international databases, including Medline (PubMed), Web of Sciences, Scopus, Cochrane Central Register of Controlled Trials (CENTRAL), and Research Registers of ongoing trials (ClinicalTrials.gov), from January 1989 to August 2017. Two independent review authors were responsible for data collection. After extracting the necessary information from the evaluated articles, metaanalysis of the data was performed using Stata version 14. Also, sources of heterogeneity among studies were determined by Meta regression.

RESULTS

In this study, among 126 articles that were extracted from primary studies, 7 papers that evaluated the effect of MgSO4 on IVH were eligible for inclusion in the meta-analysis. The results of the meta-analysis showed that pooled relative risk (95% confidence interval [CI]) was 0.80 (95% CI, 0.63 to 1.03) for the effect of MgSO4 on IVH.

CONCLUSION

RESULTS

of this study showed that although MgSO4 had a protective effect on IVH in premature infants, this effect was not statistically significant. Further studies are needed to determine the best dosage, timing, and gestational age to achieve the optimum effect of MgSO4 on IVH.

SYSTEMATIC REVIEW REGISTRATION

International Prospective Register of Systematic Reviews (PROSPERO) Identifier: CRD42019119610.

Magnesium sulfate use for fetal neuroprotection

PURPOSE OF REVIEW

The aim of this review is to describe the proposed mechanisms of action of magnesium sulfate for fetal neuroprotection, different dosing regimens of the drug that have shown benefit, and to review recent pharmacokinetic studies of the drug to better inform clinicians regarding expected benefits and remaining research questions.

RECENT FINDINGS

Retrospective secondary analysis of the beneficial effects of antenatal magnesium sulfate trial database and prospective pharmacokinetic/pharmacodynamic modeling indicate magnesium sulfate administration for duration longer than 18 h, given within 12 h of delivery, and maintaining a maternal serum level of 4.1 mg/dl may maximize the neuroprotective benefits of the drug.

SUMMARY

Magnesium sulfate in some dosage given before very preterm pregnancy delivery is beneficial for fetal neuroprotection. The exact dose, duration, and timing of administration to maximize this benefit may be more precisely studied using pharmacokinetic/pharmacodynamic modeling techniques before conducting larger randomized trials.

Antenatal magnesium sulphate and adverse neonatal outcomes: A systematic review and meta-analysis

BACKGROUND

There is widespread, increasing use of magnesium sulphate in obstetric practice for pre-eclampsia, eclampsia, and preterm fetal neuroprotection; benefit for preventing preterm labour and birth (tocolysis) is unproven. We conducted a systematic review and meta-analysis to assess whether antenatal magnesium sulphate is associated with unintended adverse neonatal outcomes.

METHODS AND FINDINGS

CINAHL, Cochrane Library, LILACS, MEDLINE, Embase, TOXLINE, and Web of Science, were searched (inceptions to 3 September 2019). Randomised, quasi-randomised, and non-randomised trials, cohort and case-control studies, and case reports assessing antenatal magnesium sulphate for pre-eclampsia, eclampsia, fetal neuroprotection, or tocolysis, compared with placebo/no treatment or a different magnesium sulphate regimen, were included. The primary outcome was perinatal death. Secondary outcomes included pre-specified and non-pre-specified adverse neonatal outcomes. Two reviewers screened 5,890 articles, extracted data, and assessed risk of bias following Cochrane Handbook and RTI Item Bank guidance. For randomised trials, pooled risk ratios (RRs) or mean differences, with 95% confidence intervals (CIs), were calculated using fixed- or random-effects meta-analysis. Non-randomised data were tabulated and narratively summarised. We included 197 studies (40 randomised trials, 138 non-randomised studies, and 19 case reports), of mixed quality. The 40 trials (randomising 19,265 women and their babies) were conducted from 1987 to 2018 across high- (16 trials) and low/middle-income countries (23 trials) (1 mixed). Indications included pre-eclampsia/eclampsia (24 trials), fetal neuroprotection (7 trials), and tocolysis (9 trials); 18 trials compared magnesium sulphate with placebo/no treatment, and 22 compared different regimens. For perinatal death, no clear difference in randomised trials was observed between magnesium sulphate and placebo/no treatment (RR 1.01; 95% CI 0.92 to 1.10; 8 trials, 13,654 babies), nor between regimens. Eleven of 138 non-randomised studies reported on perinatal death. Only 1 cohort (127 babies; moderate to high risk of bias) observed an increased risk of perinatal death with >48 versus ≤48 grams magnesium sulphate exposure for tocolysis. No clear secondary adverse neonatal outcomes were observed in randomised trials, and a very limited number of possible adverse outcomes warranting further consideration were identified in non-randomised studies. Where non-randomised studies observed possible harms, often no or few confounders were controlled for (moderate to high risk of bias), samples were small (200 babies or fewer), and/or results were from subgroup analyses. Limitations include missing data for important outcomes across most studies, heterogeneity of included studies, and inclusion of published data only.

CONCLUSIONS

Our findings do not support clear associations between antenatal magnesium sulphate for beneficial indications and adverse neonatal outcomes. Further large, high-quality studies (prospective cohorts or individual participant data meta-analyses) assessing specific outcomes, or the impact of regimen, pregnancy, or birth characteristics on these outcomes, would further inform safety recommendations. PROSPERO: CRD42013004451.

Association of histological chorioamnionitis and magnesium sulfate treatment in singleton and dichorionic twin pregnancies with preterm premature rupture of membranes: preliminary observations

Objective To evaluate the possible association between antenatal magnesium sulfate treatment with histological chorioamnionitis in patients with singleton or dichorionic twins that had preterm premature rupture of the membranes. Methods This was an observational study performed in patients admitted to the hospital with rupture of membranes before 34 weeks' gestation. The primary outcome was histological chorioamnionitis and the primary predictor was antenatal magnesium sulfate treatment. A logistic regression model was used without consideration of other antenatal medical treatments. Results Among 107 patients with preterm deliveries, 57 were admitted to the hospital before 34 weeks' gestation with preterm premature rupture of membranes. Fifty-cases were excluded from the analysis because they were admitted after 34 weeks' gestation, delivered before 24 weeks' gestation or had intrauterine fetal demise or monochorionic twins. The logistic regression analysis adjusting for maternal age, gravidity, parity, multiple gestation, gestational age at delivery, and birthweight, indicated that patients with singleton pregnancies and histological chorioamnionitis had received magnesium sulfate antenatally more frequently (χ2=6.46; P=0.01). The association between histological chorioamnionitis and magnesium sulfate treatment was not found among patients with dichorionic twin pregnancies with one intact gestational sac. Conclusions In this cohort of patients with preterm premature rupture of membranes admitted to the hospital before 34 week's gestation, those with singleton pregnancies treated antenatally with magnesium sulfate for neonatal neuroprotection had a greater rate of histological chorioamnionitis.

Fetal Neuroprotection by Magnesium Sulfate: From Translational Research to Clinical Application

Despite improvements in perinatal care, preterm birth still occurs regularly and the associated brain injury and adverse neurological outcomes remain a persistent challenge. Antenatal magnesium sulfate administration is an intervention with demonstrated neuroprotective effects for preterm births before 32 weeks of gestation (WG). Owing to its biological properties, including its action as an N-methyl-d-aspartate receptor blocker and its anti-inflammatory effects, magnesium is a good candidate for neuroprotection. In hypoxia models, including hypoxia-ischemia, inflammation, and excitotoxicity in various species (mice, rats, pigs), magnesium sulfate preconditioning decreased the induced lesions’ sizes and inflammatory cytokine levels, prevented cell death, and improved long-term behavior. In humans, some observational studies have demonstrated reduced risks of cerebral palsy after antenatal magnesium sulfate therapy. Meta-analyses of five randomized controlled trials using magnesium sulfate as a neuroprotectant showed amelioration of cerebral palsy at 2 years. A meta-analysis of individual participant data from these trials showed an equally strong decrease in cerebral palsy and the combined risk of fetal/infant death and cerebral palsy at 2 years. The benefit remained similar regardless of gestational age, cause of prematurity, and total dose received. These data support the use of a minimal dose (e.g., 4 g loading dose ± 1 g/h maintenance dose over 12 h) to avoid potential deleterious effects. Antenatal magnesium sulfate is now recommended by the World Health Organization and many pediatric and obstetrical societies, and it is requisite to maximize its administration among women at risk of preterm delivery before 32 WG.

Association of in utero magnesium exposure and spontaneous intestinal perforations in extremely low birth weight infants

OBJECTIVE

The objective of this study is to determine whether antenatal exposure to magnesium is associated with spontaneous intestinal perforation (SIP) in extremely low birth weight (ELBW) infants (⩽1000 g).

STUDY DESIGN

We identified all ELBW infants admitted to 1 of 323 neonatal intensive care units from 2007 to 2013. We used multivariable conditional logistic regression to compare outcomes in the first 21 days after birth between infants exposed and unexposed to magnesium in utero.

RESULTS

Of the 28 035 infants, 11 789 (42%) were exposed to antenatal magnesium (AM). There was no difference in the risk of SIP, odds ratio=1.08 (95% confidence interval; 0.91 to 1.29), between infants exposed and unexposed to AM. Mortality in the first 21 days after birth was lower in the magnesium-exposed infants, odds ratio=0.76 (0.70 to 0.83).

CONCLUSION

AM exposure in ELBW infants was not associated with increased risk of SIP.

Antenatal Magnesium Sulfate, Necrotizing Enterocolitis, and Death among Neonates < 28 Weeks Gestation

Objective This study aims to examine the relationship between antenatal magnesium sulfate (MgSO4) and neonatal death and/or severe necrotizing enterocolitis (NEC) among infants < 28 weeks. Methods Secondary analysis of a multicenter randomized trial of antenatal MgSO4 versus placebo administered to women to prevent death and cerebral palsy. Neonates < 28 weeks were included. The primary outcome was neonatal death before NICU discharge, and/or severe NEC (Bell criteria stage II/III). Neonates with and without death/severe NEC were compared. Results A total of 697 neonates met the criteria. Out of which 150 (21.5%) died and/or were diagnosed with severe NEC. Antenatal MgSO4 exposure was not associated with death/severe NEC in infants < 28 weeks. In a subgroup analysis of neonates < 26 weeks, treatment group assignment to antenatal MgSO4 was associated with an increased odds of death/severe NEC (adjusted odds ratio: 1.90, 95% confidence interval: 1.12-3.22, p = 0.017). Conclusions Among neonates < 26 weeks, antenatal MgSO4 was associated with death and severe NEC. Further prospective study in larger populations is needed.

Influence of magnesium sulfate on HCO3/Cl transmembrane exchange rate in human erythrocytes

Magnesium sulfate (MgSO4) is widely used in medicine but molecular mechanisms of its protection through influence on erythrocytes are not fully understood and are considerably controversial. Using scanning flow cytometry, in this work for the first time we observed experimentally (both in situ and in vitro) a significant increase of HCO3(-)/Cl(-) transmembrane exchange rate of human erythrocytes in the presence of MgSO4 in blood. For a quantitative analysis of the obtained experimental data, we introduced and verified a molecular kinetic model, which describes activation of major anion exchanger Band 3 (or AE1) by its complexation with free intracellular Mg(2+) (taking into account Mg(2+) membrane transport and intracellular buffering). Fitting the model to our in vitro experimental data, we observed a good correspondence between theoretical and experimental kinetic curves that allowed us to evaluate the model parameters and to estimate for the first time the association constant of Mg(2+) with Band 3 as KB~0.07mM, which is in agreement with known values of the apparent Mg(2+) dissociation constant (from 0.01 to 0.1mM) that reflects experiments on enrichment of Mg(2+) at the inner erythrocyte membrane (Gunther, 2007). Results of this work partly clarify the molecular mechanisms of MgSO4 action in human erythrocytes. The method developed allows one to estimate quantitatively a perspective of MgSO4 treatment for a patient. It should be particularly helpful in prenatal medicine for early detection of pathologies associated with the risk of fetal hypoxia.

[Need for resuscitation in preterm neonates less than 32 weeks treated with antenatal magnesium sulphate for neuroprotection]

INTRODUCTION

Magnesium sulphate administration is recommended for foetal neuroprotection in pregnant women at imminent risk of early preterm birth.

OBJECTIVE

To evaluate the relationship between intrapartum magnesium sulphate for foetal neuroprotection and delivery room resuscitation of preterm infants less 32 weeks.

PATIENTS AND METHOD

A prospective observational study was conducted on preterm infants less 32 weeks exposed to magnesium sulphate for neuroprotection, and a comparison made with another historic group immediately before starting this treatment. Cases in both groups that had not reached lung maturity with corticosteroids were rejected. The rates of resuscitation, morbidity and mortality for each of the groups were analysed and compared.

RESULTS

There was a total of 107 preterm, with 56 exposed to magnesium sulphate. Rate of advanced resuscitation were similar between the two groups. There were no other differences in mortality, invasive mechanical ventilation, time to first stool, and other comorbidities.

CONCLUSIONS

Intrapartum magnesium sulphate for foetal neuroprotection was not associated with an increased need for intensive delivery room resuscitation and other morbidities in these cohorts of less than 32 weeks preterm infants.

Effects of antenatal magnesium sulfate treatment on cerebral blood flow velocities in preterm neonates

OBJECTIVE

The objective of this study is to investigate the effects of antenatal magnesium sulfate (MgSO4) on cerebral blood flow (CBF) velocities in preterm neonates.

STUDY DESIGN

In this prospective case-control study, we included 53 neonates born between 26 and 34 weeks of gestation. Twenty neonates were exposed to MgSO4 antenatally and 33 were not. Serial daily Doppler flow measurements of middle cerebral artery (MCA) were performed.

RESULT

Significantly increased MCA mean velocities were found in the MgSO4 group. A progressive increase in serial Doppler measurements of MCA mean velocity from day 1 to day 5 of life was detected in both groups.

CONCLUSION

There is significant increase in MCA mean velocities in preterm neonates receiving antenatal MgSO4. This increment in CBF velocities might explain the protective role of MgSO4 in ischemic events and hypoxic brain damage.

Umbilical artery pH may be a possible confounder for neonatal adverse outcomes in preterm infants exposed to antenatal magnesium

OBJECTIVES

To determine the normal range of ionized magnesium (IMg) levels in cord blood during preterm gestation and to investigate whether antenatal Mg administration affects neonatal intraventricular hemorrhage (IVH) or patent ductus arteriosus (PDA).

METHODS

In this retrospective case-control study, we reviewed 118 pregnant women with antenatal Mg administration and their infants after they gave birth at one tertiary care center between January 2006 and December 2010. Thirty-seven cases with IVH and/or PDA were compared to 81 controls by multiple logistic regression analysis. The normal range of IMg levels was determined by another 79 subjects without any tocolytic agents and possible confounders. Perinatal and neonatal characteristics were then compared between three groups divided by the IMg levels in cord serum.

RESULTS

The normal range of IMg levels in cord blood was determined to be 0.47 ± 0.07 mmol/L, regardless of gestational weeks. IMg level in cord serum could not be a risk factor for IVH or PDA. Elevation of IMg level in cord blood resulted in an increased incidence of IVH and a decreased incidence of PDA, but not significantly. IMg level in cord blood was inversely correlated with umbilical artery pH (p = 0.067).

CONCLUSIONS

There was no significant relationship between the IMg levels in cord serum and neonatal IVH and PDA. Umbilical artery pH may be a possible confounder.

Treatment with magnesium sulphate in pre-term birth: a systematic review and meta-analysis of observational studies

Premature birth increases a child's risk of cerebral palsy and death. The aim of this work is to investigate the association between treatment with magnesium sulphate during premature deliveries and infants' cerebral palsy and mortality through a meta-analysis of observational studies. A comprehensive search of the Cochrane Library, EMBASE and the PubMed database from their inceptions to 1 October, 2010 using the keywords 'magnesium sulphate, children/infant/pre-term/premature and cerebral palsy/mortality/morbidity/adverse effects/outcome' identified 11 reports of observational studies. Two authors working independently extracted the data. A meta-analysis of the data found an association between magnesium sulphate treatment and a significantly reduced risk of mortality (RR 0.73; 95% CI 0.61-0.89) and cerebral palsy (OR 0.64; 95% CI 0.47-0.89). Antenatal treatment with magnesium sulphate during premature deliveries seems to be associated with health benefits for the infants. The effective dose and timing, however, is not defined and given the lack of mechanistic understanding of the effect of MgSO(4), a reasonable alternative is a large-scale pragmatic clinical trial.

Magnesium Sulfate Compared With Nifedipine for Acute Tocolysis of Preterm Labor

OBJECTIVE

To compare the efficacy and side effects of intravenous magnesium to oral nifedipine for acute tocolysis of preterm labor.

METHODS

A multicenter randomized trial was performed. Patients in active preterm labor who were at 24 to 33 weeks and 6 days of gestation were randomly assigned to receive magnesium sulfate or nifedipine. The primary outcome was arrest of preterm labor, defined as prevention of delivery for 48 hours with uterine quiescence.

RESULTS

One hundred ninety-two patients were enrolled. More patients assigned to magnesium sulfate achieved the primary outcome (87% compared with 72%, P=.01). There were no differences in delivery within 48 hours (7.6% magnesium sulfate compared with 8.0% nifedipine, P=.92), gestational age at delivery (35.8 compared with 36.0 weeks, P=.61), birth before 37 and 32 weeks (57% compared with 57%, P=.97, and 11% compared with 8%, P=.39), and episodes of recurrent preterm labor. Mild and severe maternal adverse effects were significantly more frequent with magnesium sulfate. Birth weight, birth weight less than 2,500 g, and neonatal morbidities were similar between groups, but newborns in the magnesium sulfate group spent longer in the neonatal intensive care unit (8.8+/-17.7 compared with 4.2+/-8.2 days, P=.007).

CONCLUSION

Patients who received magnesium sulfate achieved the primary outcome more frequently. However, delay of delivery, gestational age at delivery, and neonatal outcomes were similar between groups. Nifedipine was associated with fewer maternal adverse effects.

Effects of antenatal magnesium sulfate and corticosteroid therapy on sleep states of preterm infants

This exploratory longitudinal study was designed to compare the neonatal illness severity, sleep-wake, and respiratory sleep behaviors of preterm infants whose mothers received prenatal corticosteroids and/or magnesium sulfate (MgSO4) with those of infants whose mothers did not receive these medications. The 134 infants were divided into four groups: those whose mothers received MgSO4 only, those who received steroids only, those who received both MgSO4 and steroids, and those who received neither. The groups did not differ on infant characteristics or illness severity. Infants exposed to MgSO4 had more active sleep without rapid eye movement, indicating poorly organized active sleep. The MgSO4 -only group had higher quiet sleep regularity scores and fewer state changes. These findings suggest that fetal exposure to MgSO4 may subtly affect the central nervous system.

The combined maternal administration of magnesium sulfate and aminophylline reduces intraventricular hemorrhage in very preterm neonates

OBJECTIVE

To determine whether the adjunctive administration of aminophylline and magnesium sulfate to mothers at risk for preterm birth can reduce the rate of intraventricular hemorrhage in neonates born at less than 30 weeks of gestation.

STUDY DESIGN

A prospective study was conducted to determine whether the rate of intraventricular hemorrhage was different in patients at risk for preterm delivery treated with ritodrine, magnesium sulfate, aminophylline, and corticosteroids (group A) versus patients treated with ritodrine and corticosteroids (group B). During the study period (January 1996 to December 2001), 125 patients enrolled in the study. Treatment was assigned by alternative allocation, and the study was designed to compare the rate of intraventricular hemorrhage in neonates born before the 30th week of gestation (primary outcome), 78 newborns in group A and 68 in group B. The proportion of neonates with intraventricular hemorrhage was calculated, and data were analyzed with Student t test, chi 2 , and logistic regression analysis.

RESULTS

The frequency of severe respiratory distress syndrome needing surfactant replacement and high-pressure positive ventilation, patent ductus arteriosus, and retinopathy of prematurity was not different between the 2 groups. However, the rate of intraventricular hemorrhage was lower in neonates born before 30 weeks whose mothers received adjunctive aminophylline and magnesium sulphate (group A) than in the group that did not receive these 2 agents (group B). The overall frequency of intraventricular hemorrhage was 5.1% (4/78) versus 20.6% (14/68) ( P < .001), and the frequency of intraventricular hemorrhage grade 3-4 was 1.3% (1/78) versus 10.3 % (7/68; P < .001), respectively.

CONCLUSION

Adjunctive maternal administration of aminophylline and magnesium sulfate was associated with a significant reduction in the rate of intraventricular hemorrhage in neonates born before 30 completed weeks.

New Data on the Importance of Gestational Mg Deficiency

Chronic primary Mg deficiency is frequent. About 20% of the population consumes less than two-thirds of the RDA for Mg. Women, particularly, have low intakes. For example, in France, 23% of women and 18% of men have inadequate intakes. Mg deficiency during pregnancy can induce maternal, fetal, and pediatric consequences that might last throughout life. Studies of gestational Mg deficiency in animals show that Mg deficiency may have marked effects on parturition and postuterine involution. It has interfered with fetal growth and development, and caused morbidity from hematological effects and disturbances in temperature regulation, to teratogenic effects. Emphasis, here, is on effects of chronic clinical gestational Mg deficiency as it affects the infant. Premature labor, contributed to by uterine hyperexcitability caused by chronic maternal Mg deficiency, that can be intensified by stress, gives rise to preterm birth. If the only cause of uterine overactivity is Mg deficiency, its supplementation constitutes nontoxic tocolytic treatment, as an adjuvant treatment, that is devoid of toxicity and enhances efficacy and safety of tocolytic drugs such as beta-2 mimetics. Evidence is considered that Mg deficiency or Mg depletion can contribute to the Sudden Infant Death Syndrome (SIDS). SIDS may be a fetal consequence of maternal Mg deficiency through impaired control of Brown Adipose Tissue (BAT) thermoregulation mechanisms leading to a modified temperature set point. SIDS can result from dysthermias: hypo- or hyperthermic forms. Possibly, simple nutritional Mg supplements might be preventive. Various stresses in an infant can transform simple Mg deficiency into Mg depletion. For example, lying prone can be stressful for the baby, as can parental smoking. The role of chronopathological stress appears to be often neglected, as it constitutes a clinical form of primary hypofunction of the biological clock [with its anatomical and clinical stigma such as reduced production of melatonin (MT) and of its urinary metabolite: 6 Sulfatoxy-Melatonin (6 SMT)]. SIDS might be linked to impaired maturation of both the photoneuroendocrine system and BAT. Prophylaxis of this form of SIDS should include atoxic nutritional Mg therapy for pregnant women with total light deprivation at night for the infant. Consequences of maternal primary Mg deficiency have been inadequately studied. To determine ultimate outcomes of gestational Mg deficiency in infants, a long-term multicenter placebo-controlled prospective study should undertaken on effects of maternal nutritional Mg supplementation on lethality/morbidity in fetus, neonates, infants, children and adults, not only during pregnancy and the baby's first year, but throughout life.