Dietary sodium, potassium, and blood pressure in normotensive pregnant women: the National Health and Nutrition Examination Survey.

Dietary sodium, potassium, and sodium-to-potassium ratio are linearly associated with blood pressure in nonpregnant adults. Earlier investigations suggested null or inverse associations of blood pressure and sodium during normotensive pregnancy; findings have not been confirmed in race/ethnically diverse women or while accounting for potassium. Our purpose was to evaluate associations of blood pressure with sodium and potassium and sodium-to-potassium ratio in race/ethnically diverse normotensive pregnant women. We used cross-sectional blood pressure and dietary data from 984 women in multiple cycles of the National Health and Nutrition Examination Survey (mean age = 27.6 ± 0.2 years). We tested for differences in blood pressure across quartiles of sodium intake using Kruskal-Wallis tests and linear regression to evaluate associations of sodium, potassium, and the sodium-to-potassium ratio with systolic (SBP) and diastolic (DBP) blood pressures. We adjusted for potential confounding variables: age, race/ethnicity, education, marital status, body mass index, smoking, and month of pregnancy. SBP and DBP were similar across quartiles of sodium intake: quartile 1 (lowest sodium intake): 107/59; quartile 2: 106/59; quartile 3: 108/60; quartile 4 (highest sodium intake): 108/58 mm Hg, > 0.60 for all. Sodium (β = 0.16, 95% confidence interval (CI): -0.20 to 0.52) and potassium (β = 0.18, 95% CI: -0.24 to 0.60) and the sodium-to-potassium ratio (β = -0.54, 95% CI: -1.55 to 0.47) were not associated with SBP or DBP. Results were similar in stratified analyses. Blood pressure was similar among quartiles of sodium or potassium intake, even in analyses stratified by race/ethnicity and trimester of pregnancy. There was no association of sodium or potassium with blood pressure. Blood pressure may be insensitive to dietary sodium and potassium during normotensive pregnancy.