The impact of iodine supplementation on pregnant women in South Australia

Pregnant women in South Australia are unlikely to reach adequate iodine levels without supplementation because of poor knowledge, lack of nutritional education and supplementation. Women in South Australia, who are from a socially disadvantaged background, are mildly deficient and could benefit from supplementation during pregnancy and while breast feeding.

Iodine deficiency affects lots of people globally but it could be preventable with the use of iodized salt. Iodine deficiency during pregnancy could lead to increased rates of anomalies and intellectual impairment in children. Mild iodine deficiency during pregnancy can have effects on fetal development and cognitive function. If left untreated, pregnant women could face increased rates of stillbirths or spontaneous abortions. In Australia, the iodine intake of pregnant women has been found to be inadequate in several studies but has not been examined in the South Australian population. All women who are pregnant, breastfeeding or considering pregnancy, with the exception of women with pre-existing thyroid conditions, are recommended to take iodine supplement of 150 micrograms per day. The purpose of this study was to assess the iodine status of pregnant South Australian women throughout gestation related to their reported intake of dietary iodine-containing multivitamins and the introduction of mandatory iodine fortification of bread in Australia.

196 women were selected at the beginning of pregnancy and urine collected at 12, 18, 30, 36 weeks gestation and 6 months postpartum. The use of multivitamin supplement was recorded at each visit. Spot urinary iodine concentrations (UIC) were assessed. UIC increased significantly as pregnancy progressed when all groups were combined (P = 0.005). Post hoc comparisons indicated that UIC at 36 weeks was higher than UIC at 12, 18 and 30 weeks gestation. The consumption of dietary supplements containing iodine significantly increased UIC at 36 weeks gestation and appeared to be sustained in the postpartum period. At 30 and 36 weeks gestation, significantly more women who used iodine containing dietary supplements were above the World Health Organization (WHO) recommended guidelines for pregnant women of 150 µg/L compared to women who did not use iodine containing dietary supplements. Other than that, there was an increase in iodine status linked with the mandatory iodine fortification of bread. The median UIC of pregnant women not using an iodine-containing multivitamin during pregnancy was 68 μg/L prior to bread fortification and increased to 84 μg/L post-intervention (P = 0.01).

In conclusion, pregnant women in South Australia are unlikely to reach adequate iodine levels without supplementation because of poor knowledge, lack of nutritional education and supplementation. Women in South Australia, who are from a socially disadvantaged background, are mildly deficient and could benefit from supplementation during pregnancy and while breast feeding.

References

  1. Clifton, V.L., et al., The impact of iodine supplementation and bread fortification on urinary iodine concentrations in a mildly iodine deficient population of pregnant women in South Australia. Nutr J, 2013. 12(1): p. 32.