The cross-sectional study was carried out to assess the iodine status of pregnant women, using median urinary iodine concentration (MUI) as the measure of outcome, to document the impact of advancing gestation on the MUI in normal pregnancy.
The present study assessed the MUI in casual urine samples from 50 pregnant subjects of each trimester and 50 age-matched non-pregnant controls.
The median (range) of urinary iodine concentration (UIC) in pregnant women was 304 (102-859) μg/L and only 2% of the subjects had prevalence of values under 150 μg/L (iodine insufficiency). With regard to the study cohort, median (range) UIC in the first, second, and third trimesters was 285 (102-457), 318 (102-805), and 304 (172-859) μg/L, respectively. Differences between the first, second, and third trimesters were not statistically significant. The MUI in the controls (305 μg/L) was not statistically different from the study cohort.
The pregnant women had no iodine deficiency, rather had high median urinary iodine concentrations indicating more than adequate iodine intake. Larger community-based studies are required in iodine-sufficient populations, to establish gestation-appropriate reference ranges for UIC in pregnancy.