Yeah, do you mean evolving? Or your tamagotchi having a baby? If you mean evolving:
Your tamagotchi evolves no matter what. If on pause, a lot less soon, but it still happens. It doesn't evolve if it's dead, though, of course!
Baby: If your tamagotchi is 7+ and hasn't mated with any other tamagotchi, the matchmaker will come and offer you a partner. If you keep saying "no" until your tamagotchi is an oldie, the matchmaker won't come. You can only mate an oldie with another oldie.