Ensiyeh 2009.

Methods	Double‐blind RCT.
Participants	Pregnant women with nausea, with or without vomiting, who first attended the antenatal clinic at or before 17 weeks' gestation. Women were excluded if they had other diseases that might cause nausea and vomiting, had mental health problems, had taken tablets in the previous week that might have aggravated nausea or vomiting symptoms, refused to participate or were unable to return 1 week later for follow‐up. During the study, 80 women were eligible and 70 agreed to participate, 35 randomised to each group.
Interventions	Ginger 1 g/day or vitamin B6 40 mg/day for 4 days (for both groups: 2 capsules daily, after breakfast and dinner).
Outcomes	Severity of nausea using a VAS, number of episodes of vomiting recorded, 3 times daily during treatment for 4 days (average daily scores and mean nausea score calculated over the 4 days of treatment). At 7‐day follow‐up, treatment response was assessed using a 5‐point Likert scale (much worse, worse, same, better, much better). Median change in severity of nausea and number of vomiting episodes compared by group. Secondary outcomes also measured were: side effects and adverse effects on pregnancy outcomes such as abortion, preterm birth, congenital anomaly, perinatal death and mode of birth. Compliance was assessed by pill count and by asking women if they took the drugs.
Notes
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Low risk	35 women were randomised to the ginger group and 35 to the vitamin B6 group, using a table of random numbers.
Allocation concealment (selection bias)	Unclear risk	No details given.
Blinding of participants and personnel (performance bias) All outcomes	Low risk	Double‐blind.
Blinding of outcome assessment (detection bias) All outcomes	Low risk	Participants self‐reported outcomes.
Incomplete outcome data (attrition bias) Change in grade of nausea or vomiting at second visit compared to first	Low risk	1 woman randomised to vitamin B6 group did not return to the clinic, so she was excluded from the study. Results presented by ITT, after excluding the 1 woman.
Selective reporting (reporting bias)	High risk	Only changes in scores and number of vomiting episodes presented, as well as frequency of improvement in symptoms (by category much worse to much better) The authors stated that data collection and follow‐up took 12 weeks; also stated that pregnancy outcomes including preterm birth, perinatal death, congenital anomaly, mode of delivery were assessed, which could not have been concluded within 12 weeks. Median changes in scores presented only. Compliance/adherence to treatment is not recorded.
Other bias	Low risk	Power analysis was said to be used to determine the sample size, resulting in 31 per group to achieve a power of 0.80 with an alpha of 0.05; however effect size (presumably for primary outcome) needed for the calculation is not stated. Not likely to introduce bias.