Pregnancy presents the maternal immune system with a unique immunological challenge since it has to defend against pathogens while tolerating paternal allo-antigens expressed by fetal tissues. T helper (Th) cells play a central role in modulating immune responses and recent advances have defined distinct contributions of various Th cell subsets throughout each phase of human pregnancy, while dysregulation in Th responses show association with multiple obstetrical complications. In addition to localized decidual mechanisms, modulation of Th cell immunity during gestation is mediated largely by oscillations in sex hormone concentrations. Aberrant Th cell responses also underlie several autoimmune disorders while pregnancy-induced changes in the balance of Th cell immunity has been shown to exert favorable outcomes in the progression Th1 and Th17 driven autoimmune conditions only to be followed by post-partal exacerbations in disease.

怀孕给母体免疫系统带来了独特的免疫挑战，因为它必须防御病原体，同时耐受胎儿组织表达的父本同种抗原。辅助性 T (Th) 细胞在调节免疫反应中发挥着核心作用，最近的进展已经确定了人类妊娠各个阶段各种 Th 细胞亚群的独特贡献，而 Th 反应失调则与多种产科并发症相关。除了局部蜕膜机制外，妊娠期间 Th 细胞免疫的调节很大程度上是由性激素浓度的波动介导的。异常的 Th 细胞反应也是多种自身免疫性疾病的基础，而妊娠引起的 Th 细胞免疫平衡变化已被证明可以在 Th1 和 Th17 驱动的自身免疫性疾病的进展中产生有利的结果，但随后会导致产后疾病恶化。