No. 376-Magnesium Sulphate for Fetal Neuroprotection

Abstract Objective The objective is to provide guidelines for the use of antenatal magnesium sulphate for fetal neuroprotection of the preterm infant. Options Antenatal magnesium sulphate administration should be considered for fetal neuroprotection when women present at ≤33 + 6 weeks with imminent preterm birth, defined as a high likelihood of birth because of active labour with cervical dilatation ≥4cm, with or without preterm pre-labour rupture of membranes, and/or planned preterm birth for fetal or maternal indications. There are no other known fetal neuroprotective agents. Outcomes The outcomes measured are the incidence of cerebral palsy (CP) and neonatal death. Evidence Published literature was retrieved through searches of PubMed or Medline, CINAHL, and the Cochrane Library in December 2017, using appropriate controlled vocabulary and key words (magnesium sulphate, cerebral palsy, preterm birth). Results were restricted to systematic reviews, randomized controlled trials, and relevant observational studies. There were no date or language restrictions. Searches were updated on a regular basis and incorporated in the guideline to December 2017. Grey (unpublished) literature was identified through searching the websites of health technology assessment and health technology assessment–related agencies, clinical practice guideline collections, clinical trial registries, and national and international medical specialty societies. Values The quality of evidence was rated using the criteria described in the Report of the Canadian Task Force on Preventive Health Care (Table1). Benefits, harms, and costs Antenatal magnesium sulphate for fetal neuroprotection reduces the risk of "death or CP" (relative risk [RR] 0.85; 95% confidence interval [CI] 0.74–0.98; 4 trials, 4446 infants), "death or moderate-severe CP" (RR 0.85; 95% CI 0.73–0.99; 3 trials, 4250 infants), "any CP" (RR 0.71; 95% CI 0.55–0.91; 4, trials, 4446 infants), "moderate-to-severe CP" (RR 0.60; 95% CI 0.43–0.84; 3 trials, 4250 infants), and "substantial gross motor dysfunction" (inability to walk without assistance) (RR 0.60; 95% CI 0.43–0.83; 3 trials, 4287 women) at 2years of age. Results were consistent between trials and across the meta-analyses. There is no anticipated significant increase in health care–related costs because women eligible to receive antenatal magnesium sulphate will be judged to have imminent preterm birth. Validation Australian National Clinical Practice Guidelines were published in March 2010 by the Antenatal Magnesium Sulphate for Neuroprotection Guideline Development Panel. Antenatal magnesium sulphate was recommended for fetal neuroprotection in the same dosage as recommended in these guidelines. However, magnesium sulphate was recommended only at Sponsors Canadian Institutes of Health Research (CIHR). Summary Statement 1"Imminent preterm birth" is defined as a high likelihood of birth due to 1 or both of the following conditions (II-2): •Active labour with ≥4cm of cervical dilation, with or without preterm pre-labour rupture of membranes. •Planned preterm birth for fetal or maternal indications. Recommendations 1For women with imminent preterm birth (≤33 + 6 weeks), antenatal magnesium sulphate administration should be considered for fetal neuroprotection (I-A). 2Although there is controversy about upper gestational age, antenatal magnesium sulphate for fetal neuroprotection should be considered from viability to ≤33 + 6 weeks (II-1B). 3If antenatal magnesium sulphate has been started for fetal neuroprotection based on a clinical diagnosis of imminent preterm birth, tocolysis is no longer indicated and should be discontinued (III-A). 4Magnesium sulphate should be discontinued if delivery is no longer imminent or a maximum of 24hours of therapy has been administered (II-2B). 5For women with imminent preterm birth, antenatal magnesium sulphate for fetal neuroprotection should be administered as a 4-g intravenous loading dose, over 30 minutes, with or without a 1g per hour maintenance infusion until birth (II-2B). 6For planned preterm birth for fetal or maternal indications, magnesium sulphate should be started, ideally within 4hours before birth, as a 4-g intravenous loading dose, over 30 minutes (II-2B). 7There is insufficient evidence that a repeat course of antenatal magnesium sulphate for fetal neuroprotection should be administered (III-L). 8Delivery should not be delayed in order to administer antenatal magnesium sulphate for fetal neuroprotection if there are maternal and/or fetal indications for emergency delivery (III-E). 9When magnesium sulphate is given for fetal neuroprotection, maternity care providers should use existing protocols to monitor women who are receiving magnesium sulphate for preeclampsia/eclampsia (III-A). 10Indications for fetal heart rate monitoring in women receiving antenatal magnesium sulphate for neuroprotection should follow the fetal surveillance recommendations of the Society of Obstetricians and Gynaecologists of Canada 2007 Fetal Health Surveillance: Antepartum and Intrapartum Consensus Guideline (III-A). 11Decisions about neonatal resuscitation should not be influenced by whether or not the other received magnesium sulphate for fetal neuroprotection (II-I B).