[A study of changes in gustatory sense during pregnancy]

A change in gustatory function is generally well known as one of the manifestations in the early stage of pregnancy. However, there have been comparatively few studies of the changes in taste and gustatory function resulting from pregnancy. In particular, so far there have been no reports of investigations of two or more pregnant women in which gustatory sense in the same pregnant woman was examined serially over time. In this study, gustatory tests were performed over time on pregnant women having a normal course, so as to examine in detail the changes in gustatory function resulting from pregnancy. Selected for this study were 97 healthy pregnant women (ranging in age from 21 to 36 years, with an average of 27.9 +/- 3.2 years). Gustatory tests were performed by electrogustometry and the filter-paper disk method over the areas of the chorda tympani nerve and glossopharyngeal nerve. Of the 97 subjects, gustatory tests could be performed serially with time throughout the duration of pregnancy in 32 subjects (from 21 to 34 years old, with an average age of 28.3 +/- 2.9 years), and changes in gustatory sense with progress in pregnancy were analyzed statistically. In addition, serum trace elements were measured in 72 of the subjects. Thirty non-pregnant healthy women (from 18 to 34 years old, with an average age of 24.8 +/- 4.3 years) were used as control. The gustatory test was performed by the same person in all cases. An increase in gustatory threshold was observed in pregnant women as compared with that of non-pregnant women. Especially, a tendency of a marked decrease was noted in gustatory function in the first trimester. A marked change in secretion of hormones in the early stage of pregnancy is considered to be the underlying cause of such a decrease in gustatory function. The serum zinc level was in the normal range in the early stage of pregnancy, but it tended to decrease over the period from the midtrimester to the third trimester. Therefore, it is difficult to explain dysgeusia in the early stage of pregnancy as being associated with a deficiency of zinc.