Sympathetic pregnancy

Couvade syndrome or Sympathetic pregnancy is a poorly understood disorder where a male seems to exhibit the symptoms of pregnancy during his wife's pregnancy. This can include weight gain, loss of sexual desire, development of secondary sexual characteristics, morning sickness and differences in appetite.
Not all men exhibit Couvade, but those that do often start early in the pregnancy and the symptoms do not disappear until birth.
There is wide disagreement whether Couvade is a real illness or is merely the result of anxiety in males. It is thought that estrogen production in some males may increase during their wives pregnancy, although rising estrogen levels do not explain why these same symptoms increase in women (during pregnancy, a woman's estrogen levels rise to prevent ovulation).
It is agreed that the condition is not treatable. Patients must merely be reassured and the symptoms treated for severity.
Couvade syndrome at Wikipedia