Salt Appetite in Pregnancy

Abstract

Objective: Pregnancy is a state of sodium retention, needed to provide additional sodium to the fetus and for expansion of maternal plasma volume. Hypertension in pregnancy may be accompanied by further sodium retention, particularly when due to preeclampsia. The aim of this study was to compare salt appetite in normotensive and hypertensive pregnant women with nonpregnant normal controls. The hypothesis was that salt appetite would be increased in pregnant, compared to nonpregnant women, and further increased in hypertensive pregnancy.

Methods: Salt appetite was assessed by measuring (i) salt sensitivity, determined by taste detection threshold, preference, and tolerance data; and (ii) salt intake, assessed by food frequency questionnaire and 24-h urinary sodium. Subjects were 18 normotensive pregnant and 14 hypertensive pregnant women recruited from a hospital clinic; and 15 normal, age-matched nonpregnant controls recruited from hospital staff.

Results: Median salt detection threshold in the hypertensive pregnant women (1.44 mmol/L) was 2.6-fold higher than in nonpregnant women (0.56 mmol/L) (P = 0.003) and 1.8-fold higher than in normotensive pregnant women (0.81 mmol/L) (P = 0.027). There were no significant differences in salt preference or tolerance. Normotensive pregnant women reported greater use of discretionary salt, with less frequent consumption of low-salt products (P = 0.004). There were no group differences in sodium excretion.

Conclusion: Changes of salt appetite in pregnancy are very small. Within the limits of present methodology available to assess salt appetite, it appears unlikely that such changes contribute to the sodium retention observed in normal and hypertensive pregnancies.

Key Words:

• Detection threshold
• Hypertension
• Pregnancy
• Salt appetite
• Salt taste