Fetal microchimerism and maternal health: a review and evolutionary analysis of cooperation and conflict beyond the womb

Abstract

The presence of fetal cells has been associated with both positive and negative effects on maternal health. These paradoxical effects may be due to the fact that maternal and offspring fitness interests are aligned in certain domains and conflicting in others, which may have led to the evolution of fetal microchimeric phenotypes that can manipulate maternal tissues. We use cooperation and conflict theory to generate testable predictions about domains in which fetal microchimerism may enhance maternal health and those in which it may be detrimental. This framework suggests that fetal cells may function both to contribute to maternal somatic maintenance (e.g. wound healing) and to manipulate maternal physiology to enhance resource transmission to offspring (e.g. enhancing milk production). In this review, we use an evolutionary framework to make testable predictions about the role of fetal microchimerism in lactation, thyroid function, autoimmune disease, cancer and maternal emotional, and psychological health. Also watch the Video Abstract.

Keywords: attachment; autoimmune disease; cancer; inflammation; lactation; maternal-fetal conflict; parent-offspring conflict.

Figure 1

Pedigree of microchimerism. Microchimerism is a bidirectional exchange of fetal and maternal cells during pregnancy. During pregnancy, fetal cells (represented as orange and green circles) traffic into the maternal body, increasing in quantity throughout the gestational period. Likewise, each fetus inherits maternally derived cells (represented as purple circles). It has been predicted that younger siblings could also obtain older siblings' cells 15, as depicted with offspring 1 cells (orange) circulating within the younger sibling's body (offspring 2).

Figure 2

Mother‐offspring tug‐of‐war. Cooperation and conflict theory can elucidate the paradoxical role fetal cell microchimerism plays in maternal health. We predict that tissues involved in resource allocation, such as the brain, thyroid and breast would likely be reservoirs for fetal cells (depicted as orange circles in maternal tissues). Additionally, the maternal immune system is likely to play an active role in fetal‐maternal interactions. Within these tissues, the outcomes of these fetal‐maternal negotiations (mother‐offspring tug‐of‐war) are important in maternal health and wellbeing.