Genuine preeclampsia is a disease of first pregnancies. The protective effect of multiparity, however, is lost with change of partner. Also, exposure to semen provides protection against developing preeclampsia. Analogous to altered paternity, artificial donor insemination and oocyte donation are reported to result in a substantial increase of preeclampsia. Thus, epidemiologic studies strongly suggest that immune maladaptation is involved in the etiology of preeclampsia. Although the exact etiology of preeclampsia remains unknown, the conclusions derived from epidemiologic studies may have consequences for practicing physicians: 1) according to the primipaternity concept, a multiparous women with a new partner should be approached as being a primigravid women; 2) artificial donor insemination and oocyte donation are associated with an increased risk of developing pregnancy-induced hypertensive disorders; 3) a more or less prolonged period of sperm exposure provides a partial protection against pregnancy-induced hypertensive disorders. In the 1990s, all women with changing partners are strongly advised to use condoms to prevent sexually transmitted diseases. However, a certain period of sperm exposure within a stable relation, when pregnancy is aimed for, is associated with a partial protection against preeclampsia.