I have experienced baby fever, or the urge to have a baby multiple times over the years. I think it is a biological urge that we have no control over. Two of my children are here because I had baby fever and wanted to get pregnant so badly.
When I wanted to stifle the urge to have a baby I tried to remind myself how tough it is to have a newborn, how much cry, how much they need and how little sleep I get. I try to focus on the bad and not think about all of the good. I never found an effective why to stifle the urge though, I guess that it why I have four kids!