Magnesium sulphate was introduced for fetal neuroprotection in Australia in 2010. The aim of this study was to determine how often antenatal magnesium sulphate is used currently and its association with cerebral palsy in children born <28 weeks' gestation. Materials and Methods Participants comprised all survivors born <28 weeks' gestational age in the state of Victoria in 2016‐17, and earlier, in 1991‐92, 1997, 2005. Rates of cerebral palsy, diagnosed at two years for the 2016‐17 cohort, and at eight years in the earlier cohorts, were compared across eras. Within 2016‐17, the proportions of children exposed to antenatal magnesium sulphate were determined, and rates of cerebral palsy were compared between those with and without exposure to magnesium sulphate. Results Overall, cerebral palsy was present in 6% (11/171) of survivors born in 2016‐17, compared with 12% (62/499) of survivors born in the three earlier eras (odds ratio (OR) 0.48, 95% confidence interval (CI) 0.25–0.94; P = 0.032). Data were available for 213/215 (99%) survivors born in 2016‐17, of whom 147 (69%) received magnesium sulphate. Data on cerebral palsy at two years were available for 171 (80%) survivors with magnesium data. Cerebral palsy was present in 5/125 (4%) children exposed to magnesium sulphate and in 6/46 (13%) of those not exposed (OR 0.28, 95% CI 0.08–0.96; P = 0.043). Conclusions Antenatal magnesium sulphate is being translated into clinical practice for infants born <28 weeks' gestation, but there is room for improvement. It is associated with lower rates of cerebral palsy in survivors.