A 22-year-old primiparous woman with known glycogen storage disease type 3a presented to our hospital during her 12th week of pregnancy. Glycogen storage disease type 3 is a rare inherited disorder resulting from a deficiency of the glycogen debranching enzyme, causing the accumulation of abnormal short-chain glycogen in liver, blood cells, myocardium and striated muscle. Symptoms improve after puberty but the increased metabolism of pregnancy predisposes to hypoglycaemia, ketosis and lactic acidosis. Cardiomyopathy, distal weakness and peripheral neuropathy may present after the third decade. The patient was managed antenatally with regular cornflour feeds and was scheduled for elective caesarean delivery. She presented in early labour at 38 weeks and delivered a healthy neonate by urgent caesarean delivery under spinal anaesthesia. Intravenous dextrose infusion and regular blood glucose monitoring were used during the perinatal period to prevent hypoglycaemia. An arterial line was inserted in the operating room for frequent blood sampling and to avoid muscle cramps which could be induced by the intermittent inflation of the automated blood pressure cuff. Obstetric, anaesthetic and neonatal outcomes were uneventful.