inflation
n. 1 a sexual practice in which the practicioner inflates his or her stomach by inserting air or fluid into his or her rectum, usually with a pump.   
2 a fetish involving inflation of all or part of the body (think Violet in Charlie in the Chocolate Factory), usually the stomach. This fetish tends to be related to furries and is often portrayed in an outwardly non-sexual context. 

Inflation is a great alternative for people with a pregnancy fetish.