Mathews, Divya MPeart, Jane MSim, Robert GO'Sullivan, SusannahDerraik, José GBHeather, Natasha LWebster, DianneJohnson, Neil PHofman, Paul L2025-04-022025-04-022023-01(2023). Frontiers in Endocrinology, 14, 1080330.1664-2392https://hdl.handle.net/2292/71728<h4>Context</h4>Hysterosalpingography (HSG) using oil-soluble contrast medium (OSCM) improves pregnancy rates but results in severe and persistent iodine excess, potentially impacting the fetus and neonate.<h4>Objective</h4>To determine the incidence of thyroid dysfunction in newborns conceived within six months of OSCM HSG.<h4>Design</h4>Offspring study of a prospective cohort of women who underwent OSCM HSG.<h4>Setting</h4>Auckland region, New Zealand (2020-2022).<h4>Participants</h4>Offspring from the SELFI (Safety and Efficacy of Lipiodol in Fertility Investigations) study cohort (n=57).<h4>Measurements</h4>All newborns had a dried blood spot card for TSH measurement 48 hours after birth as part of New Zealand's Newborn Metabolic Screening Programme. Forty-one neonates also had a heel prick serum sample at one week to measure thyroid-stimulating hormone (TSH), free thyroxine (FT4), and free triiodothyronine (FT3). Maternal urine iodine concentration (UIC) and TSH in the six months after OSCM HSG were retrieved from the SELFI study for analyses.<h4>Primary outcome</h4>Incidence of hypothyroidism in the neonatal period.<h4>Results</h4>There was no evidence of primary hypothyroidism on newborn screening (TSH 2-10 mIU/L). All neonates tested at one week had normal serum TSH, FT4, and FT3 levels. However, increasing maternal peak UIC levels during pregnancy were associated with lower TSH levels (p= 0.006), although also associated with lower FT4 levels (p=0.032).<h4>Conclusions</h4>While pre-conceptional OSCM HSG in women did not result in neonatal hypothyroidism, gestational iodine excess was associated with a paradoxical lowering of neonatal TSH levels despite lower FT4 levels. These changes likely reflect alterations in deiodinase activity in the fetal hypothalamic-pituitary axis from iodine excess.<h4>Trial registration</h4>https://anzctr.org.au/Trial/Registration/TrialReview.aspx?ACTRN=12620000738921, identifier 12620000738921.Electronic-eCollectionItems in ResearchSpace are protected by copyright, with all rights reserved, unless otherwise indicated. Previously published items are made available in accordance with the copyright policy of the publisher.https://researchspace.auckland.ac.nz/docs/uoa-docs/rights.htmHumansHypothyroidismIodineThyrotropinThyroxineContrast MediaProspective StudiesPregnancyInfant, NewbornFemalecontrasthypothalamic-pituitary axishysterosalpingographynewbornoil-solublethyroid3213 Paediatrics3215 Reproductive Medicine32 Biomedical and Clinical SciencesWomen's HealthPreterm, Low Birth Weight and Health of the NewbornPediatricPerinatal Period - Conditions Originating in Perinatal Period6.1 PharmaceuticalsMetabolic and endocrineReproductive health and childbirthScience & TechnologyLife Sciences & BiomedicineEndocrinology & MetabolismCONGENITAL HYPOTHYROIDISMCONTRAST-MEDIUMNEW-ZEALANDLIPIODOLMOTHERSBORN1103 Clinical Sciences1111 Nutrition and Dietetics3202 Clinical sciencesJournal Article10.3389/fendo.2023.1080330Copyright: The authors36798662 (pubmed)1664-2392Attribution 4.0 Internationalhttp://creativecommons.org/licenses/by/4.0/