Evolution doesn't work that way.
I'm no biologist or scientist, but I'm pretty sure that if the monkey's environment changed in such a way that the monkey could no longer survive in it's current form, those monkey offspring that had some form of mutation that made them more suited to the new environment would be the ones who lived long enough to breed and so pass on that mutation.
Over several generations, the monkeys without the mutation would die out, thus the monkey evolves.
If a monkey gave birth to a human baby, the opposite would happen. The human baby is not suited to the monkey's natural environment, so the human baby would not live long enough to mate and pass on the its genes.
It seems that you need a number of things to happen; environmental change, mutations within individuals that suit the environment and time for the mutations to be passed from generation to generation.
It's not a question of a monkey just popping out a human baby.
Sorry for my long winded (and probaly unscientific)response, but I'm pretty tired of this argument.