Mature naïve B cells are retained in the placental intervillous blood and positively associate with specific chemokines in full‐term healthy pregnancy

Problem Circulating B‐cell numbers are lower during pregnancy compared with non‐pregnant women, but the underlying reasons for this are unknown. Pregnancy‐related hormones could influence B‐cell lymphopoiesis in the bone marrow, but B cells may also be recruited to the placenta. To investigate the latter, we examined whether the proportions of total B cells and B cells at different maturational stages in placental intervillous blood (IVB) differ...