A recent review of the literature suggested that thyroid autoimmunity is statistically associated with preterm delivery. This observation raises a number of follow-up questions, among them whether autoimmune function, in general, predisposes to premature delivery. A review of the English literature for the last 10 years, via PubMed search, finds strong supportive evidence for such a hypothesis. Since the fetal-placental unit represents a (semi) allograft within a maternal (allograft) recipient, it is reasonable to assume that it is subject to similar immunologic tolerance (and failure thereof) as solid organ transplants. As autoimmune responses represent a normal feature of tolerance failure in organ transplantation, similar autoimmune responses can also be expected with failure of tolerance of the fetal-maternal graft. The association of premature (and possibly also term) labor with autoimmune function may, therefore, be the consequence of abnormalities in normal fetal-placental tolerance, leading to uterine activation and labor.