Is ginger root effective for decreasing the severity of nausea and vomiting in early pregnancy?

BACKGROUND: Nausea and vomiting are both common and a source of distress for women in early pregnancy. As the cause is uncertain, numerous treatments are used empirically. Natural products are appealing because of the concern about teratogenic effects of drugs.

POPULATION STUDIED: New obstetric patients with nausea and vomiting of pregnancy were recruited for this study. Women were enrolled at or before 17 weeks’ gestation, during their first visit to an antenatal clinic in Thailand. Patients were not studied if they had other conditions that manifest with nausea or vomiting, reported current use of medications that might cause or relieve nausea or vomiting, had an inability to take medications as prescribed, and if they had mental retardation. The treatment groups did not differ significantly in terms of age (mean = 28 years), parity, gestational age (mean = 10 weeks), education, or baseline assessment of symptoms.

STUDY DESIGN AND VALIDITY: Seventy eligible women received either oral ginger 250 mg before meals and at bedtime (1 g per day) or an identical-appearing placebo for 4 days in this well-designed prospective randomized double-blind trial. Fresh ginger root was chopped, baked, ground into powder, weighed, and packed into capsules by a pharmacist for the study. Women graded nausea severity on a visual analog scale on their first study visit (baseline) and twice daily for the following 4 days, and also recorded the number of vomiting episodes in the 24 hours before treatment and each day afterward. Also, a 5-item Likert scale was used to assess the change in severity of nausea at a follow-up visit 1 week later.The appropriate study design was used for this efficacy trial. Three patients in the placebo group failed to return for follow-up visits; all other subjects completed the study and were included in the analysis. To be certain that excluding the 3 patients from the analysis did not bias the results, an intention-to-treat analysis was performed in which the symptoms of the 3 dropouts in the placebo group were assumed to improve as much as the best response in the ginger group. Concealed allocation of randomized treatment was assured by keeping treatment codes in sequence in sealed black envelopes.

OUTCOMES MEASURED: The primary outcomes were improvement in nausea symptoms (using 2 measurement scales) and decrease in vomiting episodes. Secondary outcomes included side effects and adverse effects on pregnancy outcomes (miscarriage, preterm delivery).

RESULTS: Compared with placebo, the ginger group had significantly lower nausea scores on days 3 (P=.031) and 4 (P=.05), and for the entire treatment period (P=.014). By intention-to-treat analysis (including the 3 dropouts from the placebo group), the ginger group had significantly lower nausea scores only on day 4 of treatment (P=.035). After 4 days of treatment, the proportion of women with vomiting in the ginger group was significantly lower than in the placebo group (37.5% vs 65.7%, P=.021). The number of vomiting episodes decreased significantly over the 4-day treatment period in the ginger group (1.4 ± 1.4) compared with the placebo group (0.3 ± 1.1, P<.001). These results were unchanged using intention-to-treat analysis. Using a Likert scale to assess change in severity of nausea, 87.5% of the ginger-treated women reported improvement compared with 28% in the placebo group (P <.001). Again, results remained statistically significant using intention-to-treat analysis. No important side effects or adverse effects of ginger on pregnancy outcome were noted in this study.