Data_Sheet_1_Infant Iodine and Selenium Status in Relation to Maternal Status and Diet During Pregnancy and Lactation.pdf

Iodine and selenium are essential trace elements. Recent studies indicate that pregnant and lactating women often have insufficient intake of iodine and selenium, but the impact on fetal and infant status is unclear. Here, we assessed iodine and selenium status of infants in relation to maternal intake and status of these trace elements in the birth cohort NICE, conducted in northern Sweden (n = 604). Iodine was measured in urine (UIC) in gestational week 29, and in breast milk and infant urine 4 months postpartum, while selenium was measured in maternal plasma and erythrocytes in gestational week 29, and in breast milk and infant erythrocytes 4 months postpartum, in both cases using ICP-MS. Maternal intake was assessed with semi-quantitative food frequency questionnaires in gestational week 34 and at 4 months postpartum. The median intake of iodine and selenium during pregnancy (98 and 40 μg/d, respectively) and lactation (108 and 39 μg/d, respectively) was below recommended intakes, reflected in insufficient status (median UIC of 113 μg/L, median plasma selenium of 65 μg/L). Also, breast milk concentrations (median iodine 77 μg/L, median selenium 9 μg/L) were unlikely to meet infant requirements. Median UIC of the infants was 114 μg/L and median erythrocyte selenium 96 μg/kg, both similar to the maternal concentrations. Infant UIC correlated strongly with breast milk levels (rho = 0.64, p < 0.001). Their erythrocyte selenium correlated with maternal erythrocyte selenium in pregnancy (rho = 0.38, p < 0.001), but not with breast milk selenium, suggesting formation of prenatal reserves. Our results indicate that the transport of iodine and selenium to the fetus and infant is prioritized. Still, it is uncertain whether most infants had sufficient intakes. Further, the results might indicate an involvement of iodine in asthma development during the first year of life, which is essential to follow up. The low maternal and infant dietary intake of both iodine and selenium, especially when the mothers did not use supplements or iodized table salt, suggest a need for a general screening of women and young children.

碘与硒均为人体必需的微量元素。近期研究表明，妊娠及哺乳期女性常存在碘与硒摄入不足的情况，但该情况对胎儿及婴儿健康状态的影响尚不明确。本研究针对瑞典北部开展的NICE出生队列（n=604），评估了婴儿的碘、硒营养状态与母体对这两种微量元素的摄入及营养状态之间的关联。

于妊娠第29周时，采集母体尿液样本检测尿碘浓度（UIC, Urinary Iodine Concentration），产后4个月则采集母乳与婴儿尿液样本进行对应检测；硒的检测则于妊娠第29周时采集母体血浆与红细胞样本，产后4个月采集母乳与婴儿红细胞样本，两种元素的定量分析均采用电感耦合等离子体质谱法（ICP-MS, Inductively Coupled Plasma Mass Spectrometry）。

于妊娠第34周及产后4个月，采用半定量食物频率问卷评估母体的微量元素摄入情况。结果显示，妊娠期间母体碘、硒的中位摄入量分别为98 μg/d与40 μg/d，哺乳期分别为108 μg/d与39 μg/d，均低于推荐摄入量；对应的营养状态也存在不足，表现为中位尿碘浓度113 μg/L、中位血浆硒浓度65 μg/L。此外，母乳中碘、硒的中位浓度分别为77 μg/L与9 μg/L，难以满足婴儿的营养需求。

婴儿的中位尿碘浓度为114 μg/L，中位红细胞硒浓度为96 μg/kg，两项指标均与母体对应浓度相近。婴儿尿碘浓度与母乳碘水平呈强相关性（rho=0.64, p < 0.001）；婴儿红细胞硒浓度与妊娠时期母体红细胞硒浓度相关（rho=0.38, p < 0.001），但与母乳硒水平无关联，提示婴儿体内存在产前储备的形成。

本研究结果表明，碘与硒向胎儿及婴儿的转运存在优先保障机制，但目前仍无法确定多数婴儿是否获得了充足的营养摄入。此外，研究结果还提示碘可能与婴儿出生后第一年的哮喘发生存在关联，这一发现有待进一步追踪验证。鉴于母体与婴儿的碘、硒膳食摄入量普遍偏低，尤其在未使用补剂或加碘食盐的人群中更为显著，因此建议对育龄女性及幼儿开展普遍筛查。