Bitter taste perception and severe vomiting in pregnancy

Hyperemesis gravidarum or severe vomiting during pregnancy is a condition of elusive etiology that can harm both mother and fetus. This study examined the association between increased bitter-taste perception and history of hyperemesis gravidarum. Bitter-taste perception varies genetically and can be altered with conditions that damage taste-related cranial nerves. Sixty women were divided into high- (n = 21) and low-vomit (n = 39) groups based on vomiting exposure across all pregnancies and were screened for genetic variation in taste with bitterness of saturated 6-n-propylthiouracil (PROP) delivered on filter paper. Supertasters perceive PROP as intensely bitter; nontasters, as only weakly. Each reported their history of dysgeusia (persistent taste) and taste-related pathology (otitis media and head trauma). The vomit groups did not differ in the frequency of supertasters, but the high-vomit group had fewest nontasters. The high-vomit group also reported dysgeusia most frequently. A subsample (13 high-vomit and 18 low-vomit women) rated the taste intensity of sodium chloride (1 mol), sucrose (1 mol), citric acid (0.0032 mol), and quinine hydrochloride (0.001 mol) applied to areas innervated by cranial nerves VII and IX. The groups only varied significantly in bitterness of quinine hydrochloride. High-vomit women tasted least bitterness on the anterior tongue (chorda tympani branch of VII) and highest bitterness on the posterior tongue (cranial nerve IX) and palate (superficial petrosal branch of VII). In high-vomit women, elevated bitterness on the posterior tongue and palate does not appear related to hydrochloric acid exposure in vomitus; it may explain the occurrence of dysgeusia. This pattern of spatial taste perception may indicate altered oral sensations that if present during pregnancy, could increase the risk of hyperemesis.