Maternal iodine dietary supplements and neonatal thyroid stimulating hormone in Gippsland, Australia

Pregnant women are at particular risk of iodine deficiency due to their higher iodine requirements. Iodine is known to be essential for normal growth and brain development, therefore neonatal outcomes in mildly iodine deficient areas, such as Gippsland, are a critical consideration. This study aimed to investigate whether iodine supplementation prevented iodine insufficiency as determined by neonatal thyroid stimulating hormone (TSH) screening criteria.

Gippsland-based women aged >=18 years, in their third trimester of pregnancy, provided self-reported information regarding their iodine supplement use and consent to access their offspring's neonatal TSH screening data. 126 women consented to participate, with 111 women completing all components of this study.

Only 18.9% of participants followed the National Health and Medical Research Council (NHMRC) recommendation of 150 μg/day iodine supplement, with 42.3% of participants not taking any supplements, or taking supplements with no iodine or insufficient iodine. The remaining women (38.7%) were taking supplements with doses of iodine much higher (200-300 μg) than the NHMRC recommended dose or were taking multiple supplements containing iodine. When correlating iodine intake to their neonates' TSH, no correlation was found. When iodine supplementation usage was categorised as below, equal to, or above NHMRC recommendations there was no significant difference in neonatal TSH.

This study found that iodine supplementation appeared to prevent maternal iodine insufficiency when measured against neonatal TSH screening criteria.