Possible immunological basis for recurrent spontaneous abortions: a review

In normal pregnancy, the pregnant mother paradoxically tolerates the semi-allogeneic foetus until term. Experimental and clinical data to explain such tolerance in man reflects the involvement of multiple mechanisms.

To review the data pertaining to the experimental and clinical efforts to explain why the mother immunologically tolerates a semi-allogeneic pregnancy to term.

A review of the literature on state of the art thinking among researchers and clinicians on recurrent spontaneous abortions is summarised.

A large body of recently published data strongly suggest that a breakdown in immunological maternal-foetal interactions may lead to occasional or recurrent foetal loss. Immunoregulatory activities involving blocking antibodies, regulatory factors, immunological cells, hormones, structural proteins and cytokines constitute the pregnancy-sustaining network.

The majority of the evidence reviewed points to the involvement of immunological factors in successful pregnancies. However, the underlying mechanisms are inadequately explained, are largely speculative and require more focused investigation. A complete understanding of the mechanisms involved would enhance our capacity to develop rational ways of addressing recurrent pregnancy losses.