Are pregnant women in New Zealand iodine deficient? A cross-sectional survey.

Severe iodine deficiency in pregnancy can result in cretinism. There is growing concern that less severe iodine deficiency may also affect fetal growth and development. A handful of prior small New Zealand studies focussed on pregnant women living in Dunedin. This study utilised biochemical, clinical and dietary indices to assess iodine status of 170 women living throughout New Zealand. The median urinary iodine concentration (UIC) of the women was 38 μg/L, well below the 150 μg/L cut-off value that indicates adequate iodine status; 7% of women had goitre. Not surprisingly, iodine intake was also low at 48 μg/day. The majority of women had TSH and FT4 concentrations within pregnant reference ranges, suggesting that despite the low UIC observed in these women, thyroid hormone production appeared unaffected.