A systematic review and meta-analysis of the effect and safety of ginger in the treatment of pregnancy-associated nausea and vomiting

Table 2 Pooled estimates of effect size (95% confidence intervals) expressed as weighted relative risk for adverse events and side-effects of ginger versus control group (Placebo, Vitamin B ₆ , Dimenhydrinate)

Outcome	Number of studies	RR	95% CI	Heterogeneity
Outcome	Number of studies	RR	95% CI	Chi²	I²(%)
*Ginger versus placebo*
^#Allergic reaction [30]	1	3.00	0.12 to 72.20
^#Dehydration [30]	1	3.00	0.12 to 72.20
^#Spontaneous abortions [29, 30]	2	3.14	0.65 to 15.11	0.00	0
Abdominal discomfort [29]	1	3.27	0.14 to 77.57
Diarrhea [29]	1	3.27	0.14 to 77.57
Drowsiness [29]	1	2.82	0.12 to 66.62
Headache [29]	1	1.31	0.44 to 3.89
Heartburn[19, 29, 30]	3	5.03	0.89 to 28.61	0.35	0
Worsening of symptoms requiring pharmaceutical treatment [30]	1	0.33	0.01 to 8.02
*Ginger versus vitamin B* ₆
^#Arrhythmia [20]	1	0.51	0.05 to 5.46
^#Spontaneous abortions [21, 27]	2	0.49	0.17 to 1.42	1.67	40
Belching [27]	1	27.18	1.63 to 453.06*
Burning sensation after capsule ingestion [27]	1	1.01	0.21 to 4.91
Drowsiness [20, 28]	2	0.75	0.48 to 1.19	0.18	0
Dry retching [27]	1	0.93	0.76 to 1.15
Heartburn [20, 28]	2	2.35	0.93 to 5.93	1.03	3
Vomiting [27]	1	1.51	0.26 to 8.91
*Ginger versus Dimenhydrinate*
Drowsiness [26]	1	0.08	0.03 to 0.18**
Heartburn [26]	1	1.44	0.65 to 3.20

^#Major adverse events (serious complications, possibly detrimental to the mother or fetus) (authors’ judgement); rest considered minor (discomfort, but manageable side effects) - sorted alphabetically, first major then minor events.
*Indicates significant finding: Ginger significantly increased the risk of belching compared to vitamin B₆.
**Indicates significant finding: Dimenhydrinate significantly increased the risk of drowsiness compared to ginger.
RR, Relative risk; CI, confidence interval.