The recommended daily dose of ginger for the treatment of PNV is 1000 mg. It is difficult to know whether the four studies administered ginger at a dose close to that recommended given the lack of details on the method of extraction, solvent used, dose of the extract and the dried herb equivalent. The only study reporting the dried herb equivalent was Willetts et al. who administered ginger at a dose equivalent to 4.5 g of dried ginger daily. This exceeds the maximum recommended daily dose for pregnancy of 4 g. This is a cause for some concern as ginger doses of more than 4 g per day may produce uterine stimulating effects, which could adversely affect the pregnancy. High doses of ginger may also aggravate pre-existing conditions, such as cholelithiasis, or contribute to cardiac arrhythmia, CNS depression and heartburn. Notwithstanding, such adverse events were not identified by Willetts et al. Table 2 illustrates how the consumption of ginger from a variety of sources can result in a woman exceeding the maximum recommended daily dose of ginger for pregnancy.