Are Pregnant Women Iodine Sufficient in Sri Lanka? An Assessment Using Urinary Iodine Concentration

Background : Adequate maternal iodine intake is essential for optimal foetal brain development, and even mild deficiency can impair cognitive outcomes. Sri Lanka introduced Universal Salt Iodisation (USI) in 1995, yet emerging evidence indicates possible gaps in iodine ststus among pregnant women. This study aimed to assess urinary iodine concentration (UIC) among first-trimester pregnant women to evaluate iodine sufficiency. Methods : Across-sectional study was conducted in three selected districts representing different geographic and demographic settings. Antenatal clinics were sampled using a stratified approach to capture sectoral variation. Spot urine samples were collected from 337 first-trimester pregnant women during routine clinic visits. Median urinary iodine concentration (mUIC) was used as the primary indicator of iodine status, following WHO criteria. Result: The overall mUIC was 135.9 µg/L, below the WHO-recommended range of 150–249 µg/L for pregnancy. District level variation was notable, with the highest mUIC in Colombo and the lowest in Kandy (168.1 vs 106.4 µg/L; p<0.01). Urban-rural differences were not statistically significant (p>0.05). More than half of participants (52.8%) were iodine deficient (mUIC <150µg/L), while only 22.6% were within the adequate range. Conversely, 20.8% exhibited UIC levels “above requirements” and 3.9% had “excessive” levels (≥500 µg/L), with both categories higher in Colombo (26.0% and 8.0% respectively). Conclusion ; Nearly three decades after the implementation of USI, iodine insufficiency persists among pregnant women in Sri Lanka, with wide district disparities and emerging pockets of excess intake. These findings highlight the need for strengthened monitoring of iodine nutrition during pregnancy and periodic evaluation of the salt iodisation programme to prevent mild iodine deficiency during pregnancy to ensure optimal foetal development.