Iodised salt contribution to iodine nutrition status of pregnant and lactating women.

Sufficient iodine intake by pregnant and lactating women is crucial to their offspring's cognitive development. The aim of the present study was to explore the impact of iodised salt intake on the iodine status of pregnant and lactating women. Thirty towns were selected from 211 towns in the rural areas of Shijiazhuang city using probability proportionate to size sampling in this cross-sectional survey. In each selected town, forty pregnant women and forty lactating women were randomly selected to contribute urine samples to determine iodine content. The median urinary iodine content (UIC) of 1200 pregnant women in all was 146 (interquartile range (IQR) 88-239) μg/l. The median UIC in the first, second and third trimesters were 166 (IQR 92-276) μg/l, 145 (IQR 83-248) μg/l and 134 (IQR 79-221) μg/l, respectively. The median UIC in the first trimester was significantly higher than that in the third trimester (P= 0.04). The median UIC of 1200 lactating women in all was 120 (IQR 66-195) μg/l. Their median UIC in every 4-week block was higher than the WHO criteria except in weeks 25-28 and weeks 33-36 of lactation. Pregnant women's median UIC did not correlate with median salt iodine (MSI) (P= 0.402); however, there was a linear correlation between MSI and the lactating women's median UIC (P= 0.007). Iodised salt failed to provide adequate iodine to pregnant women possibly due to limited intake of iodised salt during pregnancy, though it was found to provide adequate iodine to lactating women in the rural areas of Shijiazhuang city.