𝐅𝐀𝐍𝐅𝐈𝐂 𝐓𝐄𝐑𝐌𝐈𝐍𝐎𝐋𝐆𝐘 [1]

Mpreg

Mpreg = Male Pregnancy 

Refers to stories featuring a male character capable of conceiving and/or carrying a child within their own body. May or may not include the birth as well. Obviously considered AU, but often contain some kind of acceptable reasoning or explantion for the male becoming pregnant. This can frequently be a squick for many people, so should be listed in the author's warnings.