Maternal and neonatal iodine status in Dakshina Kannada district of Karnataka, India

This study was designed to assess iodine status of mother-fetus dyad by estimation of spot urine iodine concentration (UIC) in the study district. It is a cross-sectional study of 250 pregnant women with euthyroid status and their term neonates residing in Dakshina Kannada district. Neonates with foetal growth restriction or requiring intensive care were excluded. Median UIC was quantified using modified Sandell-Kolthoff reaction by microplate method. World Health Organization (WHO) classification was used to categorise the iodine status of pregnant women. Among 250 pregnant women, the majority were primigravida (38%). Median maternal thyroid stimulating hormone (TSH) was 1.54 mIU/l, and median UIC was 352 mcg/l. Urine iodine levels were insufficient (<150 mcg/l) in 1.2% (n = 3), adequate (150-249 mcg/l) in 9.2% (n = 23) and above requirement (250-499 mcg/l) in 89.6% (n = 224); none had excess (> 500 mcg/l). Median birth weight was 3,000 g and head circumference was 34 cm. Median cord blood TSH was 8.1 mIU/l, and median UIC 344.5 mcg/l. All the newborns had adequate (> 100 mcg/l) iodine status, including those born to mothers with insufficient values. Maternal and newborn median UIC showed positive correlation (r = 0.139; p = 0.028). Iodine statuses were above requirement or adequate in pregnant women from the study district and their neonates, respectively, indicating successful salt iodisation.