Similarities and differences of dietary and other determinants of iodine status in pregnant women from three European birth cohorts

Abstract

Acknowledgements EUthyroid project: This project has received funding from the European Union´s Horizon 2020 research and innovation programme under grant agreement No 634453. ALSPAC: We are extremely grateful to all the families who took part in this study, the midwives for their help in recruiting them, and the whole ALSPAC team, which includes interviewers, computer and laboratory technicians, clerical workers, research scientists, volunteers, managers, receptionists and nurses. The UK Medical Research Council and Wellcome (Grant ref: 102215/2/13/2) and the University of Bristol provide core support for ALSPAC. This publication is the work of the authors and Dr Bath will serve as a guarantor for the contents of this paper. ALSPAC data collection is funded from a wide range of sources, a comprehensive list of which is available on the ALSPAC website (http://www.bristol.ac.uk/alspac/external/documents/grant-acknowledgements.pdf). The existing iodine measurements in ALSPAC were funded from (i) the NUTRIMENTHE project, which received a research grant from the European Community's 7th Framework Programme (FP7/2008-2013) under grant agreement 212652; and (ii) a Ph.D. studentship that was funded by Wassen International and the Waterloo Foundation (2009-2012). We would like to thank Dr Pauline Emmett for helping with the dietary analysis of the ALSPAC food frequency questionnaire.

Maternal and neonatal outcomes and determinants of iodine deficiency in third trimester of pregnancy in an iodine sufficient area

“…In another study in China the type of dietary salt, maternal age, occupation, consumption of complementary micronutrients and seafood were found to affect urinary iodine meaningfully [32]. In another study by Dineva et al seafood consumption, iodinated salt intake and maternal age were found to be defining factors in urinary iodine concentration of the mother [33]. However, this study did not find any relation of statistical significance between maternal iodine deficiency and maternal complications of the pregnancy.…”

Iodine status during pregnancy and at 6 weeks, 6, 12 and 18 months post‐partum

“…Similarly, in a study where pregnant women from three large cohorts in Europe were included, intake of milk and dairy products was the main dietary determinant of iodine status. Other dietary determinants were fish and shellfish and cereals (Dineva et al, 2020). Breastfeeding gave significantly reduced odds of having UIC above 100 μg/L in our study, which is not unexpected because large amounts of iodine are secreted into breast milk (Laurberg & Andersen, 2014).…”

“…Participants who reported the use of thyroid medication during pregnancy were excluded. Variables to be included in the models were chosen on a theory‐based approach and consisted of covariates known from previous studies to influence iodine status in pregnancy (Dineva et al, 2020; Henjum, Aakre, et al, 2018; Henjum et al, 2017). For iodine supplement use, an unadjusted model, then a model adjusted for maternal age, parity, breastfeeding status, time and time*supplement use was performed.…”

Response to Letter to the Editor from Levie et al: “Association of Maternal Iodine Status With Child IQ: A Meta-Analysis of Individual Participant Data”

“…The use of flexible modeling and various sensitivity analyses excludes that skewness of the data caused by values above 300 µg/g affected would affect our results. Although we had incomplete data on iodine supplement use in two of the three cohorts (7), high values of the UI/Creat in our study population do not necessarily reflect iodine supplement use. For example, it is unlikely that British pregnant women in the early 1990s would have taken iodine-containing supplements as there was, and still is, no legislation concerning iodine nutrition in the UK.…”