Svensson-Arvelund J, Ernerudh J, Buse E, Cline JM, Haeger JD, Dixon D, Markert UR, Pfarrer C, De Vos P, Faas MM. The placenta in toxicology. Part II: Systemic and local immune adaptations in pregnancy. Toxicol Pathol. 2014; 42(2):327-38.