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Information for Clinicians
Maternity Department
Magnesium Sulphate for Neuroprotection in Preterm Labour
Presentation
Cerebral palsy is a well-recognised complication of preterm birth. While the survival of infants born
preterm has improved, the prevalence of cerebral palsy has risen, with 25% of all cases of cerebral palsy
occurring in infants born at less 34 weeks gestation.
A number of RCTs have been performed looking at the role of magnesium sulphate (MgSO4) for
neuroprotection of the premature neonate. Meta-analyses of these have shown that the use of antenatal
magnesium sulphate reduces cerebral palsy and motor deficits in preterm infants, irrespective of the
reasons for preterm birth.

Consider for all women in labour between 24 and 30 weeks gestation. If decision is made not to
give MgSO4 between 24 and 30 weeks, document reason why not on proforma.

Consider for women between 23 and 24 weeks, if the couple have been counselled by the
neonatal team and have decided they want ‘everything done’ if there are signs of life.
Regime
1) Loading dose: Magnesium sulphate 4g given over 5 minutes
Draw up 8mls (4g) of 50% magnesium sulphate and 12mls 0.9% sodium chloride (giving a
total volume of 20mls)
2) Maintenance dose: Magnesium sulphate 1g/hour for 24 hours or until delivery
Draw up 20mls (10g) of 50% magnesium sulphate and 30mls 0.9% sodium chloride (giving a
total volume of 50mls) into a 50mls syringe. Give as IV infusion using a syringe driver, setting
the infusion rate at 5mls/hour. The infusion needs to continue for 24 hours or until delivery,
which ever is sooner.
STOP maintenance infusion after delivery or after 24 hours, whichever is sooner
NB Please complete preterm labour proforma
If women require transfer to another unit, magnesium sulphate should be commenced
while awaiting the transfer transport. Continue maintenance dose until ambulance arrives
but DO NOT administer during transfer. Communicate treatment to team on arrival at unit
Ref.: M82 – Magnesium Sulphate for Neuroprotection in Preterm Labour
Approved by: Vicky Tinsley – Head of Nursing and Midwifery
Author: Jo Ficquet - Consultant Obstetrician
Date of Issue: 23 December 2014
© Royal United Hospital Bath NHS Trust
Version: 1.0
Approved on: 04 December 2014
Review date: 04 December 2017
Page 1 of 2
Monitoring whilst on MgSO4
1.
Hourly tendon reflexes.
If loss of reflexes, inform senior obstetrician STOP infusion and send serum MgSO4 levels.
Restart infusion at 0.5g/hour, if level < 4mmol/L or if reflexes return.
2.
Monitor urine output
If urine output < 100mls/4 hours or urea >10, inform senior obstetrician, check serum MgSO4
levels every 4-6 hours (therapeutic range 2-4mmol/L). If serum MgSO4 level > 4mmol/L, stop
MgSO4 infusion.
3.
Hourly respiratory rate (RR) and O2 saturation
If RR < 14, inform senior obstetrician and stop MgSO4. Start facial oxygen at 15L/minute.
Consider giving Calcium Gluconate to reverse the effects of MgSO4 rapidly.
10ml of 10% Calcium Gluconate IV over 2-5 minutes if magnesium toxicity is likely
CAUTION:


MgSO4 given to women taking Nifedipine may cause profound hypotension.
If magnesium Sulphate is given too rapidly it can cause Ventricular Fibrillation or cardiac
arrest
Contraindications
MgSO4 should be avoided in women with myasthenia gravis, as it may precipitate a crisis.
References
RCOG Scientific Advisory Committee Opinion Paper. Magnesium Sulphate to prevent cerebral palsy
following preterm birth. 2011 Aug.
Handbook of obstetric Medicine, Catherine Nelson-Piercy, 2005.
Ref.: M82 – Magnesium Sulphate for Neuroprotection in Preterm Labour
Approved by: Vicky Tinsley – Head of Nursing and Midwifery
Author: Jo Ficquet - Consultant Obstetrician
Date of Issue: 23 December 2014
© Royal United Hospital Bath NHS Trust
Version: 1.0
Approved on: 04 December 2014
Review date: 04 December 2017
Page 2 of 2