whereas the others used either capsules or syrup
containing approximately 1 g of ginger daily26,32–35
(Table 1).
We applied the Cochrane Risk of Bias assessment
to the 6 studies; they achieved a score of at least 3 of
6 and were deemed to be of satisfactory quality.
Our primary outcome was the improvement of
pregnancy-related nausea and vomiting, which was
reported in all 6 studies: 180 of the 256 subjects in the
ginger group and 126 of the 252 subjects in the
placebo group reported improvement in symptoms of
nausea and vomiting. In view of the interstudy variation
in the duration and form of intervention, a random
effects model was adopted. The pooled OR was
4.89, with a 95% CI of 1.88 to 12.73 (see Table 2).
The Cochrane Q-statistic was significant at 33.72,
with a degree of freedom of 5 (P .0001) (Table 3).
A synthesis Forest plot was generated (Figure 1), and
the corresponding funnel plot is included for reference
(Figure 2). Relative risk was calculated at 1.76
(95% CI, 1.18 –2.65), and the number needed to treat
for a positive effect was calculated to be 5.