Methods	Randomised double-blind placebo-controlled trial.
Participants	342 pregnant women at </= 17 weeks’ gestation.
Interventions	Oral pyridoxine (vitamin B6) received 20 10 mg tablets to be taken every 8 hours (6-8 am, 2-4 pm, 10 pm-12 md) for 5 days Placebo: identical-looking tablets to be taken in the same regime
Outcomes	Primary outcome: change in the secondary outcome severity of nausea; measured in a Visual Analogue Scale in centimetres (10 cm 0 as no nausea to 10 as nausea as bad as it could be). Average daily nausea scores calculated and then mean nausea score over 5 days Secondary outcome: change in the number of vomiting episodes
Notes
Risk of bias
Item	Authors’ judgement	Description
Adequate sequence generation?	Yes	Patients were then randomised into 2 groups by a table of random numbers
Allocation concealment?	Yes	A list that revealed drug codes was kept by the research assistant and was not accessible to the physicians
Blinding? Change in grade of nausea or vomiting at second visit compared to first	Yes	Pyridoxine and placebo tablets were prepared by the hospital pharmacy and packed similarly in envelopes in an envelope containing 20 tablets each. Neither the patients nor the physicians knew the identity of the drugs administered. A list that revealed drug codes was kept by the research assistant and was not accessible to the physicians
Incomplete outcome data addressed? Change in grade of nausea or vomiting at second visit compared to first	Yes	All included in analysis except 6 who did not return for follow up (2 in placebo group, 4 in treatment group)
Free of selective reporting?	Yes	All outcomes reported.
Free of other bias?	Yes	No other sources of bias apparent.