We are debating if a Play Yard will be more practical than a crib. We believe that it will be safer than a crib, and also easy to carry around.
What we don't know is if the play yard mattress will provide the same back support and comfort level that a baby (new born) will require to grow healthy.
I believe what you are referring to as a "Play Yard" I call a "Pack-and-Play," if that is correct here is my answer:
We use a pack and play when traveling, mainly at grandma's house, and my son does not appear to have a problem with it. But then again he will sleep almost anywhere without complaint. In a swing, on the floor, a car seat, while being held, etc... And he is rarely on his back.
But I do not think the slightly padded bottom of the pack and play is providing the comfort of a foam or spring mattress in a proper crib. Maybe you could find or make a mattress to fit the pack and play, but they are usually square and mattresses are usually not.
As a newborn, for the first couple of months we propped our son up an a pillow, one of those curved breast feeding pillows, and he would sleep anywhere at all.
For babies and kids be wary of mattresses that are too soft (ex: a water bed = big no no) that could suffocate the baby. You want a mattress that is firm but also comfortable. If you know you will definitely use a play yard, buy that first. They have travel play yards (i.e. "Graco Pack and Play Travel Play Yard") catered to newborns too that allow you to raise the level and then you can lower it as they grow.
Your baby will let you know if they are uncomfortable and you can make modifications:
A lot of parenting is trial and error. We bought a crib and didn't really used it either. Our baby napped in a swing the first 3 months. It was nice to have a place to put them where you know they won't hurt themselves though when you need a break or both hands.
My older daughter (now 3 years old) spent the first 12 months of her life in a "pack-and-play," or a "play yard"... it had an insert that made it a bit more shallow, so it was easier to get her in and out of it during night time and nap time. Neither my husband nor I are sensitive sleepers, we don't have back issues, and my daughter is a strong, healthy girl with no troubles sleeping pretty much anywhere. She's never had any back support issues or pain, and her sleep has been really, really wonderful! (At 5 months of age she was sleeping 12 hours straight through the night!)
My younger daughter spends her time between a cosleeper, a pack-and-play, and a bassinet. She seems to have restful sleep in each location, and I haven't noticed a difference between any of them.
Then again, it was my experience that both girls slept on my chest better than any bed!
