Neurodevelopmental delay is associated with neurodevelopmental disorders. Prenatal metal exposure can potentially cause neurodevelopmental delays in children. This study examines whether prenatal exposure to mercury (Hg) and selenium (Se) is associated with the risk of neurodevelopmental delays in children up to 4 years of age. Children enrolled in a prospective birth cohort of the Japan Environment and Children’s Study were examined. Hg and Se levels in maternal (n_child = 48,731) and cord (n_child = 3,083) blood were analyzed by inductively coupled plasma-mass spectrometry. Neurodevelopmental delays were assessed in children between the ages of 0.5 to 4 years using the Ages and Stages Questionnaires, Third Edition. The association between exposure and outcomes was examined using the generalized estimation equation models. In maternal blood, compared to participants with Se levels in the first quartile (83.0 to < 156 ng/g), the odds ratio (95 % confidence intervals) for problem-solving ability in children of mothers in the third (168 to < 181 ng/g) and fourth quartiles (181 to 976 ng/g) were 1.08 (1.01 to 1.14) and 1.10 (1.04 to 1.17), respectively. Furthermore, communication, gross and fine motor skills, and problem-solving delays were also observed. However, prenatal Hg levels in maternal and cord blood and Se levels in the latter were not associated with neurodevelopmental delays in children. Thus, the findings of this study suggest an association between Se levels in maternal blood and slightly increased risks of neurodevelopmental delays in children up to the age of 4 years.

神经发育迟缓与神经发育障碍有关。产前接触金属可能会导致儿童神经发育迟缓。本研究探讨产前接触汞 (Hg) 和硒 (Se) 是否与 4 岁以下儿童神经发育迟缓的风险相关。对参加日本环境与儿童研究前瞻性出生队列的儿童进行了检查。 通过电感耦合等离子体质谱法分析母体（n 名_儿童 = 48,731）和脐带（n_{名儿童= 3,083）血液中的汞和硒水平。}使用第三版年龄和阶段问卷对 0.5 至 4 岁儿童的神经发育迟缓进行了评估。使用广义估计方程模型检查暴露和结果之间的关联。在母体血液中，与硒水平处于第一四分位数的参与者（83.0 至 < 156 ng/g）相比，母亲的孩子解决问题能力的比值比（95% 置信区间）处于第三四分位数（168 至 < 181） ng/g）和第四四分位数（181 至 976 ng/g）分别为 1.08（1.01 至 1.14）和 1.10（1.04 至 1.17）。此外，还观察到沟通、粗大和精细运动技能以及解决问题的延迟。然而，母体和脐带血中的产前汞水平以及后者中的硒水平与儿童神经发育迟缓无关。因此，这项研究的结果表明，母血中的硒含量与 4 岁以下儿童神经发育迟缓的风险略有增加之间存在关联。