Maternal Immunological Adaptation During Normal Pregnancy

Abstract

The risk and severity of specific infections are increased during pregnancy due to a combination of physiological and immunological changes. Characterizing the maternal immune system during pregnancy is important to understand how the maternal immune system maintains tolerance towards the allogeneic fetus. This may also inform strategies to prevent maternal fatalities due to infections and optimize maternal vaccination to best protect the mother-fetus dyad and the infant after birth. In this review, we describe what is known about the immunological changes that occur during a normal pregnancy.

Keywords: cellular immune response; fetal; gestation; humoral immune response; immune system; immunity.

Figure 1

Changes in maternal immune system components during pregnancy based on current literature. Trimester-specific changes that are not described in the literature are not shown and represented as gaps and stops in lines (i.e. complement activation and regulatory proteins, CH50 and B regulatory cells). Dashed lines indicate that reduction in B cell might happen during first or second trimester. There are controversies in the literature regarding the dynamics of total and subclasses of IgG combined to draw a definite pattern (thus it is not described in the figure, see full text for details). Fucosylation of Fc portion of IgG is similar to non-pregnancy but at very high levels. *Complement activation proteins: C3a, C4a, C5a, Serum Complement Membrane Attack Complex SC5b9; Complement regulatory proteins: Decay-accelerating factor (CD55), C3 inhibitor pregnancy-associated plasma protein A.