Wang 2014b.

Study characteristics
Methods	RCT
Participants	66 women Inclusion criteria: primiparous, singleton pregnancy, elective caesarean, age 18‐35, 37‐42 weeks' gestation, ASA I‐II, normal prenatal examinations, normal renal and liver function, no medical history of heart or lung disease, no fetal abnormalities Exclusion criteria: hypertension, cardiovascular or cerebrovascular disease, placenta praevia, abnormal fetal development, contraindications to spinal anaesthesia, endocrine disorders, recent administration of 5‐HT reuptake inhibitors or drugs for treatment of migraines Setting: China
Interventions	Prophylactic ondansetron versus control 5 min prior to spinal anaesthesia: Group 1: 4 mg IV ondansetron (diluted to 5 mL with physiological saline) Group 2: 5 mL IV physiological saline All women received the same standardised monitoring, cannulation, spinal anaesthetic technique and dose, standardised crystalloid coload and postdelivery oxytocin If hypotension occurred, 100 μg IV phenylephrine was administered, and repeated every 2 min as required until SBP > 80% baseline If bradycardia occurred, 0.5 mg IV atropine was administered If SpO2 < 95%, mask assisted O2 inhalation was given at 3 L/min If nausea or vomiting occurred, 12.5 mg IV promethazine was administered If intractable pain, assisted anaesthetics were added or GA performed and patient was excluded
Outcomes	Maternal: incidence of hypotension, bradycardia, nausea and vomiting, peak block height, total consumption of phenylephrine Neonatal: umbilical cord gases, Apgar scores at 1 min and 5 min
Notes	Hypotension was defined as maternal SBP < 80% baseline Bradycardia was defined as heart rate < 50 bpm Hypertension was defined as SBP > 140 mmHg or DBP > 90 mmHg
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Low risk	Computer‐generated
Allocation concealment (selection bias)	Low risk	Opaque, sealed, sequentially numbered envelopes
Blinding of participants and personnel (performance bias) All outcomes	Low risk	Study drugs prepared by anaesthetist not directly involved in the patient scare or assessment. Solutions were in syringes of similar appearance, labelled study drug
Blinding of outcome assessment (detection bias) All outcomes	Low risk	As above, anaesthetist was blinded
Incomplete outcome data (attrition bias) All outcomes	Low risk	Group 1: 1 woman excluded from BP analysis due to intractable shivering preventing BP measurement, 2 women excluded from blood gas analysis due to insufficient samples Group 2: 1 woman completely excluded due to failed spinal anaesthesia, 2 women excluded from blood gas analysis because of insufficient samples
Selective reporting (reporting bias)	Low risk	None apparent
Other bias	Low risk	None apparent. Grant from Wuxi Municipal Health Bureau