Thoughts of foster care - grieving my 'perfect child'

Today I was listening to the radio on the way home from my first ever laser hair removal treatment (yep it's time to get out there and try new things).  There was a segment on parenting children with disabilities.  A woman rang up to recount her story of how she was going to give her daughter born with Downs Syndrome up for adoption as she didn't think she could cope. Her daughter was in hospital, as she didn't want to take her home and get attached when she didn't want to keep her.  The first week in hospital she had problems with her heart and had to stay there for 5 weeks, then she went to foster care.  The mother and her husband signed the adoption papers then had 28 days to change their mind, after 24 hours she'd changed her mind and decided it was her daughter and she wanted to raise her.  She says she never really looked back after that.  She felt she'd made the decision about adoption as she was grieving the loss of the perfect child she'd dreamed of having.  Grieving this perfect child is something that really resonates with me- at this age I feel it's all so hard to keep trying to get pregnant and there is a higher risk of having a child with Downs Syndrome.  Then there's the possibility of foster care and parenting a child with lots of problems.  I think partly my concerns about foster care are tied up with grieving the dream of parenting the child I'd dreamed of.  Plus the logistics of parenting a child that will always have to have constant contact with birth parents which means never moving out of the state basically - that is a HUGE hurdle to get around!