The problem will not be the additional workload, but the reception and subsequent growth, if despite this feature there should be no response it would be wasted work.
Then i believe 2 variations with minor differences might be the best choice, and also believe the hole pregnant part itself will attract players and keep current ones.
Also side note really love that the game is not just go here then bang this one but has real relationships with the girls and a great story.
I myself am all about the pregnant, and would love alternate forms if it's feasible. Maybe poll and select 2 to demo it on, and see how much effort it takes and how much people love it? I can't imagine that something major like your New Life -wouldn't- be a smash hit, but thats just me. Im over the moon about the concept, but again- its a great game as is, and i wouldn't want you to burn out