The use of ginger by pregnant women to treat nausea and vomiting is widespread, however concerns have been expressed in some circles about the safety of such a practice. In particular, the clinical trials that have been conducted in the past have only observed the use of ginger over a 4-day time period, which does not lend confidence to the safety of the extensive use of ginger during the first trimester of pregnancy.
Recently the results of three studies (two of them from Australia) have been published which provide further evidence for the safety and efficacy of ginger during pregnancy. The first study was conducted at the Royal Hospital for Women in Randwick NSW. (1) The effect of a ginger extract on the symptoms of morning sickness was investigated in 120 women in a double-blind, randomized, placebo-controlled trial. Participants were less than 20 weeks pregnant who had experienced morning sickness daily for at least a week and had experienced no relief of symptoms through dietary changes. They received 125 mg of ginger extract (equivalent to 1.5 g of dried rhizome) or placebo four times per day for 4 days. The nausea experience score was significantly less for the ginger extract group relative to placebo after the first day of treatment and this difference was observed for every treatment day. While retching was reduced to some extent, there was no significant effect observed on vomiting. Follow-up of the pregnancies revealed normal ranges of birth weight, gestational age, Apgar scores (see footnote below) and frequencies of congenital abnormalities. Four participants in the ginger group withdrew from the trial due to reflux and heartburn caused by the relatively high dose of ginger used.
In the second Australian study, the effect of 1.05 g of ginger or 75 mg of vitamin B6 per day were compared using a randomized, double-blind design. (2) The trial involved 291 South Australian women less than 16 weeks pregnant and either treatment was given for 3 weeks. Differences from baseline in nausea and vomiting scores were estimated for both groups at days 7, 14 and 21 of the trial. The trial found that ginger was equivalent to vitamin B6 in reducing nausea, retching and vomiting. There was no evidence of different effects between the two treatments at each of the three assessment points of the trial. Morning sickness improved in little more than half of the women in each group. No differences in congenital abnormalities were detected between the study groups and the overall risk of pregnancy complications did not differ. In addition, there were no differences found for any other birth outcomes. The authors concluded that, because of the relatively small size of the study, firm evidence of the safety of ginger in pregnancy is still required and further systematic research on the risks and benefits of ginger during pregnancy would be of great clinical relevance.
The third study was conducted in Canada. (3) Rather than being a clinical trial, it was a comparative observational study where pregnant women who took ginger were compared to a control group. The outcome of 187 pregnancies where women took ginger for nausea and vomiting were compared with 187 pregnancies where no antiemetic medications were used. The study found that there were no statistical differences in pregnancy outcomes between the ginger group and the comparison group, with the exception of more infants weighing less than 2.5 kg occurring in the comparison group (12 versus 3, p [less than or equal to] 0.001). In addition, a total of 66 women who had used ginger alone for a minimum of 3 days completed an effectiveness score for the treatment. The mean score of 3.3 [+ or -] 2.9 indicated mild effectiveness for the ginger in the treatment of nausea and vomiting of pregnancy. However, various types of ginger were consumed by the women including capsules, ginger tea, fresh ginger, pickled ginger, candied ginger and so on. A total of 49% of the women used capsules, with the rest using the various other preparations. When the authors compared the effectiveness of the different forms of ginger they found that the capsules were significantly more effective than all the other preparations combined (4.2 [+ or -] 3.1 versus 1.7 [+ or -] 0.7, p < 0.001). No information was provided concerning the length of time that ginger was used by the women. Again the authors stressed that conclusions about the safety of ginger during pregnancy were limited by the relatively small size of their survey.
Commentary: These studies are timely given the widespread use of ginger by pregnant women throughout the world. For example, a recent survey of 400 women found that 36% had used herbal products during their pregnancy with an average of 1.7 products per woman. (4) The proportion of women using herbs increased throughout the first, second and third trimesters. The most commonly used herbs were Echinacea, herbal-based iron supplements, ginger, chamomile and cranberry. The South Australian study is particularly significant because of the longer time period over which ginger was used by the pregnant women. The results of the Canadian study are also useful because the survey observed the actual usage of ginger and (although not stated), presumably ginger was used by these pregnant women for substantial periods of time.
Footnote
The Apgar score was introduced in 1973 and is a method developed by Dr. Virginia Apgar to evaluate a newborn's adjustment to extrauterine life (life outside the uterus). Five items (heart rate, respiratory effort, muscle tone, reflex irritability, and color) are evaluated 60 seconds after birth and again five minutes later on a scale of 0-2, 0 being the lowest, 2 being normal. The five numbers are added for the Apgar score. A score of 0-3 represents severe distress, 4-7 indicates moderate distress, and a score of 7-10 predicts an absence of difficulty in adjusting to extrauterine life.
References
1. Willetts KE, Ekangaki A, Eden JA. Effect of a ginger extract on pregnancy-induced nausea: a randomised controlled trial. Aust N Z J Obstet Gynaecol 2003; 43: 139-144
2. Smith C, Crowther C, Willson K et al. A randomized controlled trial of ginger to treat nausea and vomiting in pregnancy. Obstet Gynecol 2004; 103: 639-645
3. Portnoi G, Chng, LA, Karimi-Tabesh L et al. Prospective comparative study of the safety and effectiveness of ginger for the treatment of nausea and vomiting in pregnancy. Am J Obstet Gynecol 2003; 189: 1374-1377
4. Nordeng H, Havnen GC. Use of herbal drugs in pregnancy: a survey among 400 Norwegian women. Pharmacoepidemiol Drug Saf 2004; 13(6): 371-380
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