Methods	Randomised, double-blind placebo-controlled study.
Participants	74 pregnant women consented to participate; 59 women completed the protocol
Interventions	Treatment group: vitamin B6 - 25 mg tablets every 8 hours for 72 hours Placebo: identical appearing tablets to be taken using the same regimen
Outcomes	Severity of nausea: marked on 10 cm unmarked Visual Analogue Scale: 0 as no nausea and 10 as worst possible nausea; recorded by women 4 times daily (am, noon, pm, bedtime) for the 3 days of treatment Number of episodes of emesis per 24 hours recorded daily for 3 days
Notes
Risk of bias
Item	Authors’ judgement	Description
Adequate sequence generation?	Yes	Randomised by a table of numbers.
Allocation concealment?	Unclear	Not described.
Blinding? Change in grade of nausea or vomiting at second visit compared to first	Yes	All individuals involved in the study except for the pharmacist were blinded to the nature of the medication It is not clear at what stage group allocation became known.
Incomplete outcome data addressed? Change in grade of nausea or vomiting at second visit compared to first	Unclear	20.2% drop-out rate high, not clear which group attrition was in
Free of selective reporting?	Unclear	After data collection but before data analysis, the authors say that they arbitrarily divided the patients into 2 subgroups according to the severity of their nausea - patients with a nausea score of greater than 7 were in the severe nausea group and those with scores less than or equal to 7 were categorised in the mild to moderate subgroup and these 2 groups were then compared. As the results showed that there was a significant improvement in the severe nausea subgroup who received the intervention, bias in the arbitrary post hoc cut-off for severity subgroup bias cannot be ruled out Unclear reporting - average of averages, mean change from baseline (standard error of the difference in the means) etc
Free of other bias?	Yes