Postnatal thyroid hormone changes enable the neonate to be adapted for postnatal life. Several factors can affect this adaption. In this review, we summarized the studies that reported the association among the delivery factors and neonatal thyroid hormones and thyroid stimulating hormone. A comprehensive literature search was performed in PubMed, Web of Science, and Scopus up to March 2020, to identify the studies investigating the relationship between delivery factors, especially the mode of delivery and labor pain, and neonatal thyroid hormones and TSH. Finally, in this review study, of 157 articles obtained in the initial search, 25 eligible studies were reviewed. Various maternal, fetal/neonatal, and obstetric factors affected neonatal TSH and thyroid hormones. Among various influencing factors, mode of delivery, labor pains, and duration of labor have a strong relationship with neonatal thyroid hormones and need to be considered for interpretation of neonatal thyroid status. The majority of the studies revealed that vaginal deliveries (instrumental or natural) lead to higher levels of cord TSH compared to elective cesarean section. This can be explained by the increased secretion of catecholamine during labor. It has been suggested that blood TSH and thyroid hormone levels are affected by perinatal stress events such as maternal anxiety, labor pains, fetal distress, and other stimulants of the catecholamine response. These changes may act as the trigger to increase thyroid hormone levels for adapting of neonates in the first hours after birth. This assumption needs to be re-evaluated by performing comprehensive and well-designed studies.

中文翻译：

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分娩因素和新生儿甲状腺激素水平：系统评价

出生后甲状腺激素的变化使新生儿能够适应出生后的生活。有几个因素会影响这种适应。在这篇综述中，我们总结了报道分娩因素与新生儿甲状腺激素和促甲状腺激素之间关联的研究。截至 2020 年 3 月，在 PubMed、Web of Science 和 Scopus 中进行了全面的文献检索，以确定调查分娩因素（尤其是分娩方式和分娩疼痛）与新生儿甲状腺激素和 TSH 之间关系的研究。最后，在本综述研究中，在最初检索获得的 157 篇文章中，对 25 项符合条件的研究进行了综述。各种孕产妇、胎儿/新生儿和产科因素影响新生儿 TSH 和甲状腺激素。在各种影响因素中，分娩方式、阵痛、和分娩持续时间与新生儿甲状腺激素有很强的相关性，需要考虑来解释新生儿甲状腺状态。大多数研究表明，与择期剖宫产相比，阴道分娩（器械或自然分娩）会导致更高水平的脐带 TSH。这可以通过分娩期间儿茶酚胺分泌增加来解释。有人提出，血液 TSH 和甲状腺激素水平受围产期压力事件的影响，例如产妇焦虑、分娩疼痛、胎儿窘迫和其他儿茶酚胺反应的兴奋剂。这些变化可能会触发增加甲状腺激素水平，以适应新生儿在出生后最初几个小时内的适应情况。需要通过进行全面和精心设计的研究来重新评估这一假设。