25 Interesting Facts About Human Blood

White Blood Cells Are Necessary for Pregnancy

It is well known that white blood cells are important for a healthy immune system. What is less known is that certain white blood cells called macrophages are necessary for pregnancy to occur. Macrophages are prevalent in reproductive system tissues. Macrophages assist in the development of blood vessel networks in the ovary, which is vital for the production of the hormone progesterone. Progesterone plays a critical part in the implantation of an embryo in the uterus. Low macrophage numbers result in reduced progesterone levels and inadequate embryo implantation.