Subject: Can a (live birth) mammal zygote be brought to term in a shelled egg?

I was wondering if a fetus from a live bearing mammal could be placed in a
shelled egg and brought to term.  Would a platypus egg be better to use then a
bird egg?  I was thinking you could use eggs that had equivalent sizes to baby
mammals...like maybe a robin with baby mice.  The ultimate goal of this question
is whether a human fetus could be brought to term this way, for woman with
birthing difficulties, or women who just don't want to experience the pain!! 
I'd imagine an ostrich egg would be too small, but perhaps one could be
egineered to be big enough.   In any event, in making an artificial womb, I
think a lesson has to be taken from the egg, and have all the nutrient's
available at once instead of fed to the embryo over time.  Have any experiments
been done with this?    PS I have searched and searched on mad sci...over 850
items on egg alone, and there are no direct answers to this question.  Thanks
for answering.

Re: Can a (live birth) mammal zygote be brought to term in a shelled egg?