It is a very natural emotion. I feel guilty for having the same feelings towards any women who announces her PG...i get really judgemental thinking 'why has she got pg...they have only been together 1 year, not 10 years etc.' or 'why is she pg, she is realy unstable, I would be a much better mum.' it is a horrible judgemental thing to think, I feel ashamed for even having those thoughts.
My little sis is 28/9 weeks pg, but I feel different towards her. i feel jealous, but in a funny way...kind of 'I wish it was me too'....not that 'I wish it was me instead of her', if you know what I mean.
emotions do funny things to us...the urge to have a baby must be one of the strongest I have ever felt.