False pregnancy False pregnancy False pregnancy, also known as phantom, hysterical pregnancy, pregnancy scares or pseudocyesis, is the appearance of clinical or subclinical signs and symptoms associated with pregnancy when the person is not actually pregnant. False pregnancy may sometimes be purely psychological. It is generally believed that false pregnancy is caused by changes in the endocrine system of the body, leading to the secretion of hormones that cause physical changes similar to those during pregnancy. Some men experience the same illnesses as a woman would experience while pregnant when their partner is pregnant (see Couvade syndrome), possibly caused by pheromones that
Pregnancy in fish researchers have historically been reluctant to use the term "pregnancy" for non-mammals because of the highly developed form of viviparity in eutherians. Recent research into physiological, morphological and genetic changes associated with fish reproduction provide evidence that incubation in some species is a highly specialized form of reproduction similar to other forms of viviparity. Although the term "pregnancy" often refers to eutherian animals, it has also been used in the titles of many international, peer-reviewed, scientific articles on fish, e.g. Five modes of reproduction can be differentiated in fish based on relations between the zygote(s) and parents: There are two