Ref (type)	Population	Outcome, Interventions	Results and statistical analysis	Effect size	Favours
Nausea
Systematic review	70 women, <17 weeks' gestation Data from 1 RCT	Mean improvement in nausea score 4 days of treatment 2.1 with ginger 1.5 with placebo	MD +0.60 95% CI –0.51 to +1.71 P = 0.29 Per-protocol analysis demonstrated a significant difference in favour of placebo: MD 1.20; 95% CI 0.22 to 2.18; P = 0.017 (ginger group, n = 32; placebo group, n = 35)		Not significant
Systematic review	23 women, gestational age 7–11 weeks Data from 1 RCT	Proportion of women reporting little improvement in nausea day 9 3/13 (23%) with ginger 8/10 (80%) with placebo	RR 0.29 95% CI 0.10 to 0.82 P = 0.019	Moderate effect size	ginger
RCT	99 women, mean gestational age of 9 weeks In review	Mean nausea experience scores assessed by Rhodes Index of Nausea, Vomiting and Retching day 1–day 4 with ginger in oral capsules taken 4 times daily for 4 days with placebo taken 4 times daily for 4 days Absolute results reported graphically	Reported as significant P value not reported	Effect size not calculated	ginger
RCT	62 women, 7–17 weeks' gestation	Mean change from baseline in nausea score assessed by 10 cm visual analogue scale (0 = no nausea, 10 = severe nausea) over 4 days 2.57 with ginger powder in biscuit, 5 biscuits per day for 4 days 1.39 with placebo biscuits, 5 biscuits per day for 4 days	P = 0.01		ginger
Systematic review	67 women, mean gestational age 13±3 weeks Data from 1 RCT	Improvement in nausea intensity assessed by visual analogue scale (0 = absence of nausea, 10 = most severe condition of nausea) 4 days 27/32 (84%) with ginger capsule taken 4 times daily for 4 days 20/35 (56%) with placebo taken 4 times daily for 4 days	RR 1.48 95% CI 1.07 to 2.04 P = 0.018	Small effect size	ginger
Vomiting
RCT	70 women, less than or equal to 17 weeks' gestation In review	Proportion of women with vomiting 4 days 12/32 (38%) with ginger in oral capsules taken 4 times daily 23/35 (66%) with placebo	RR 0.57 95% CI 0.34 to 0.95 NNT 4 95% CI 2 to 12	Small effect size	ginger
Systematic review	26 women, gestational age 7–11 weeks Data from 1 RCT	Proportion of women who continued vomiting 6 days 4/12 (33%) with ginger 8/10 (80%) with placebo	RR 0.42 95% CI 0.18 to 0.98 P = 0.046	Moderate effect size	ginger
RCT	99 women, mean gestational age of 9 weeks In review	Retching day 1–day 2 with ginger in oral capsules taken 4 times daily for 4 days with placebo taken 4 times daily for 4 days Absolute results not reported	Reported as significant P value not reported	Effect size not calculated	ginger
RCT	99 women, mean gestational age of 9 weeks In review	Vomiting day 1–day 4 with ginger in oral capsules taken 4 times daily for 4 days with placebo taken 4 times daily for 4 days Absolute results not reported	Reported as not significant P value not reported		Not significant
RCT	62 women, 7–17 weeks' gestation	Mean change from baseline in number of vomiting episodes over 4 days of treatment 0.96 with ginger powder in biscuit, 5 biscuits per day for 4 days 0.62 with placebo biscuits, 5 biscuits per day for 4 days	P = 0.243		Not significant
RCT	67 women, mean gestational age 13±3 weeks In review	Decrease in vomiting frequency 4 days 50% with ginger capsule 4 times daily for 4 days 9% with placebo taken 4 times daily for 4 days	P <0.05		ginger
Nausea and vomiting (composite)
RCT 3-armed trial	68 women, mean gestational age ranged from 9.5–10.3 weeks	Mean Rhodes Index baseline and over 4 days of treatment with ginger essence 3 times daily for 5 days with placebo 3 times daily for 5 days	P = 0.004 P value represents between group comparison for intensity of change in nausea and vomiting		ginger
Symptom improvement
RCT	70 women, less than or equal to 17 weeks' gestation In review	Proportion of women with improved symptoms (non-specifically described) 7 days 28/32 (88%) with ginger in oral capsules taken 4 times daily 10/35 (29%) with placebo	RR 0.18 95% CI 0.07 to 0.45	Large effect size	ginger
RCT	62 women, 7–17 weeks' gestation	Proportion of women reporting improvement of symptoms (Likert scale better or much better responses) 4 days 28/32 (88%) with ginger powder in biscuit, 5 biscuits per day for 4 days 21/30 (70%) with placebo biscuits, 5 biscuits per day for 4 days	P = 0.043		ginger