You’ve probably heard that women’s taste changes during pregnancy, but is it actually true? If given a blank check, an elegant study to answer this question would be a prospective longitudinal study evaluating taste perception and sensitivity in women before, during, and after their pregnancy. Realistically speaking, this would be very difficult to execute; however, a study like this would be ideal because studying the same women provides the least inherent variability and fewer potential sources of bias, or confounders (versus a retrospective study/self-report). Interestingly enough, less than a dozen publications have come close to this study design over the last century.
Anecdotally, people report that taste returns to normal after pregnancy, which leads one to believe that any variation is temporary and likely caused by an elevation in hormone levels, for instance estrogen and progesterone, that return to baseline after delivery. However, this is speculative in nature, and it should be noted that pregnancy is also accompanied by a host of physiological changes and adaptations to support fetal development and growth beyond just these two hormones. In addition to the endocrine system, maternal changes include increased weight gain, increased blood volume, and adjustments to immune tolerance. Interestingly, over the last few decades, these very same factors have all been implicated in altering taste.
Thus, we set out to review the existing studies of human pregnancy and taste to catalog the trends occurring across pregnancy, to see how we may leverage what we are beginning to understand about taste modulation from human and non-human research. This may help to generate hypotheses for future investigations to ultimately question the long held assumption that these changes in taste are solely driven by hormone fluctuations.
A limited number of longitudinal studies have been carried out, with even fewer examining women prior to pregnancy and then continuing to follow their taste changes during pregnancy and on through the postpartum period. Generally, the overall findings show a little inconsistency, possibly due to a lack of agreement on experimental design.
The most studied in correlation with pregnancy, most studies either report no change in sweet tastes or a mild decrease in the ability to taste sweetness – usually specific to the first trimester.
Again, sour taste function has been found to either be unaffected by pregnancy, or to decrease – again specifically in the first trimester.
Findings vary regarding pregnant women’s response to salty foods. One study suggested that as citric acid becomes less unpleasant during the second and third trimesters, this promotes increased electrolyte ingestion, and therefore increases cravings for salty foods such as pickles. Several studies have also shown that pregnant women have a higher tolerance for salty tastes, suggesting that salt taste function is altered during pregnancy.
Of the four basic tastes, bitterness shows the least consensus across studies. Some propose that pregnant women perceive bitterness more intensely, and suggest that this could be in order to help avoid toxins during critical phases of fetal development. Other studies have found that bitterness is perceived less intensely during pregnancy, and continues into the postpartum period.
Additionally, recent findings show that taste can be modulated in healthy non-pregnant adults, through mechanisms such as the endocrine system beyond estrogen and progesterone, and via the growing number of inflammatory factors noted to impact taste. Researchers should consider these other paradigms to explain modulation of the taste system in pregnancy.
A better understanding of changes to taste in health and disease could contribute to understanding the cause and effect of gestational obesity, hypertension, diabetes, and hyperemesis gravidarum. Furthermore, we may be able to begin to tease apart the changes in taste occurring during pregnancy to promote a healthy pregnancy, and whether deviations from the norm could be an indicator of negative health consequences to come for mother or offspring.
Featured image credit: Pregnant mother. CC0 Public Domain via Pexels.