Magnesium is not consistently neuroprotective for perinatal hypoxia-ischemia in term-equivalent models in preclinical studies: a systematic review

There is an important unmet need to further improve the outcome of neonatal encephalopathy in term infants. Meta-analyses of large controlled trials now suggest that maternal magnesium sulfate (MgSO4) therapy is associated with a reduced risk of cerebral palsy and gross motor dysfunction after premature birth, but that it has no effect on death or disability. Because of this inconsistency, it remains controversial whether MgSO4 is clinically neuroprotective and, thus, it is unclear whether it would be appropriate to test MgSO4 for treatment of encephalopathy in term infants. We therefore systematically reviewed the preclinical evidence for neuroprotection with MgSO4 before or after hypoxic-ischemic encephalopathy (HIE) in term-equivalent perinatal and adult animals. The outcomes were highly inconsistent between studies. Although there were differences in dose and timing of administration, there was evidence that beneficial effects of MgSO4 were associated with confounding mild hypothermia and, strikingly, the studies that included rigorous maintenance of environmental temperature or body temperature consistently suggested a lack of effect. On balance, these preclinical studies suggest that peripherally administered MgSO4 is unlikely to be neuroprotective. Rigorous testing in translational animal models of perinatal HIE is needed before MgSO4 should be considered in clinical trials for encephalopathy in term infants.

Different magnesium sulphate regimens for neuroprotection of the fetus for women at risk of preterm birth

BACKGROUND

The effectiveness of antenatal magnesium sulphate for neuroprotection of the fetus, infant, and child prior to very preterm birth, when given to women considered at risk of preterm birth, has been established. There is currently no consensus as to the regimen to use in terms of the dose, duration, the use of repeat dosing and timing.

OBJECTIVES

To assess the comparative effectiveness and adverse effects of different magnesium sulphate regimens for neuroprotection of the fetus in women considered at risk of preterm birth.

SEARCH METHODS

We searched the Cochrane Pregnancy and Childbirth Group's Trials Register (31 December 2011).

SELECTION CRITERIA

Randomised trials comparing different magnesium sulphate regimens when used for neuroprotection of the fetus in women considered at risk of preterm birth. We planned to include cluster trials. We planned to exclude quasi-randomised trials and those with a crossover design. We planned to include trials published as full-text papers, along with those published in abstract form only.

DATA COLLECTION AND ANALYSIS

We planned that at least two review authors would assess trial eligibility.

MAIN RESULTS

No eligible completed trials were identified.

AUTHORS' CONCLUSIONS

Although strong evidence supports the use of antenatal magnesium sulphate for neuroprotection of the fetus prior to very preterm birth, no trials comparing different treatment regimens have been completed. Research should be directed towards comparisons of different dosages and other variations in regimens, evaluating both maternal and infant outcomes.