Pregnancy and the postpartum period are associated with significant changes in levels of several hormones, such as estrogen, progesterone, cortisol and possibly catecholamines. Moreover, several autoimmune diseases such as rheumatoid arthritis tend to remit, develop or exacerbate during pregnancy or the postpartum period. Thus, the question arises: are the changes in the hormones and the expression of autoimmune diseases during these periods causally linked, or are these associations an epiphenomenon? Here we suggest that a causal link might be provided through differential neuroendocrine regulation of Th1-type and Th2-type cytokine production.