Carvalho 2010.

Study characteristics
Methods	RCT
Participants	Inclusion criteria: All women undergoing elective caesarean deliveries under spinal anaesthesia Full‐term pregnancy N = 164 women randomised, data collected on 150 women Exclusion criteria: All women who claim allergy or hypersensitivity to dimenhydrinate; women with history of vomiting within 24 hours prior to caesarean birth; women with history of GI or psychiatric diseases and morbid obesity; women receiving any of the following drugs within 24 hours before the study: opioids, antiemetics, H2 antagonists, phenothiazine and corticosteroids; women with severe pregnancy‐induced hypertension
Interventions	Intervention: antihistamine (Comparison 4) Dimenhydrinate single dose, 25 mg, IV, diluted in 9.5 mL normal saline. N = 78 women Comparator: placebo single dose, 10 mL normal saline, IV N = 71 women
Outcomes	Incidence of pre or post‐delivery nausea as reported by the women; etc.
Notes	Setting: Samuel Lunenfeld Research Institute, Mount Sinai Hospital, Toronto, Ontario, Canada, M5G 1X5 Dates: not reported Funding source: not reported Declaration of interest: not reported Trial registration: NCT00791960 Conference abstract only.
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Unclear risk	Not reported
Allocation concealment (selection bias)	Unclear risk	Not reported
Blinding of participants and personnel (performance bias) All outcomes	Unclear risk	As above
Blinding of outcome assessment (detection bias) All outcomes	Unclear risk	No mention of blinding of outcome assessors
Incomplete outcome data (attrition bias) All outcomes	Unclear risk	Unclear how many women were actually randomised
Selective reporting (reporting bias)	High risk	Apgar scores and other neonatal data not reported
Other bias	Unclear risk	Insufficient methodology in the conference abstract to be able to assess other possible biases