One of the most common physical sequelae of pregnancy is nausea and vomiting. While exact figures vary, most research indicates that anywhere from 70 to 85 percent of pregnant women have nausea and/or vomiting during pregnancy (Flake et al., 2004; Wilkinson, 1999). Quinlan and Hill (2003) indicate that generally nausea and vomiting begin between the fourth and seventh week after a woman's last menstrual period, and resolves by the 20th gestational week for 90% of women; Wilkinson (1999) notes simply that "morning sickness usually starts early in the pregnancy with symptoms peaking at 8-9 weeks and then disappearing by about the 14th week." Meltzer (2000) wisely notes "Studies of nausea and vomiting in pregnancy are often made more challenging because of the subjective nature of the symptom of nausea versus the objective sign of vomiting."
One indisputable danger from uncontrolled nausea and vomiting is development of hyperemesis gravidarum. Hyperemesis gravidarum, defined as, "persistent vomiting that is serious enough to cause fluid and electrolyte disturbance" (Jewell, 2003a) often necessitates hospitalization to rehydrate the woman and ameliorate electrolyte imbalances. Though the prevalence of hyperemesis gravidarum is estimated at only .3% (Fisher-Rasmussen, 1990) to 3% (Hollyer et al., 2002), its consequences can be tragic if untreated.
Nausea and vomiting during pregnancy (NVP) impacts more than only the pregnant woman. Hollyer et al. (2002) report study findings where almost 50% of employed women reported reduced work efficiency due to pregnancy-related nausea and vomiting, 25-66% reported having to take time off from work, with almost 50% reporting that the nausea and vomiting negatively affected their relationship with their partner including having an adverse effect on the partner's [italics added] day-to-day life.
Clearly, finding a treatment to lessen NVP is long overdue, but fraught with risks. Since the 1960's thalidomide tragedy, research on medications used for pregnant women has been limited. Ethical concerns preclude "experimentation" of medications or treatments for a pregnant woman, thus much research relies on that which is known to date or is discovered spuriously.
Treatments for NVP span both "traditional" (Western) and "complementary" (Eastern) medicine. A lengthy discussion of these treatment alternatives is beyond the scope of this paper, though Jewell (2003b) provides a concise summary in Clinical Evidence. This paper focuses on one particular treatment for NVP, the use of Zingiber officinale (ginger). As will be noted, ginger can be found in varying forms (syrup, tea, capsules, food products) and this variation may confound the inter-study correlations.
Zingiber officinale (ginger), as noted in the Alternative Medicine Review (2003), has a long history of medicinal use, primarily in India and China, dating back 2,500 years. Though the reasons for its anti-emetic effect are not well defined, it is thought, "the aromatic, spasmolytic, carminative, and absorbent properties of ginger suggest it has direct effects on the gastrointestinal tract (Alternative Medical Review, 2003). Combining the known benefits of ginger in Ayurvedic and "Eastern"