Carin and Diane, I also agree that there is no right or wrong way to 'deal' with mares and foals. It is all up to the the owner concerned and obviously takes into account the mare herself, the health of the new baby, the weather and most importantly of all, the facilities at various farms.
Here I have grass, grass and more grass!! LOL!! My girls are out 24/7 throughut the year. The brood mares come in at nights for the month before they foal and usually stay in at nights for the month afterwards. As they are such 'fatties', they only get a cupful of 'balancer' night and morning but ad lib hay during the nights - as their digestive systems are used to food during the night hours. Without exception they all love to be in their stables - they enjoy all the fuss and attention! BUT there is no way that I could keep them stabled completely after they foaled, it would not be good for their systems to change from daytime (10-12 hours) grass to 'dry' food 24/7. So, weather allowing, we lead the mare (foal following with sometimes a little encouragement!) out to an area of good fresh grass for around 1 to 2 hours that first day - we dont let the mare loose but sit/stand with her while she grazes. This gives her some Dr. Green to help get her digestion working again and the foal has the chance to wander slowly about in its own time - no danger of the mare taking off, causing her baby to follow at a fast pace before it is ready.
Depending upon the mare (temperament/sensible wise) we will either do this for two or three days (after the first day she will be led out twice each day for her grass time) or we will let her and the foal loose in our 'special' 1/2 acre paddock. From there the mares move to the 'mare and foal' field for a full day outside, where she will join her friends and their foals, or if she is the first to foal, she will go there alone to await the arrival of the next mare to foal. Any chance of bad weather and all mares and foals are gathered back in to the stables until the weather improves. This is another reason why I like my foaling stables to be as big as possible - at least 12x12, most of ours are 15x12, so the foals have plenty of room to scamper around if they get stuck inside for a while due to the weather!
I do agree with Diane's opinion in that I also feel that foals gain more strength through being allowed to walk around in large spaces rather than being kept in stalls, but I also think that more damage can be done if you just let a mare go and she trots off or takes off at her own pace with a new baby struggling to keep up. Hence my method of hand grazing for a day or two, to give a foal the chance to 'find it's legs'. But I also know that I couldn't keep my girls fully stabled for more than a day - they would gallop and race about once given the freedom again. They seem to be fooled/kept happy by their short grazing stints for a day or two, and when let loose, they just wander away, instead of going off at a rush!
But, as it has already been said, it is all up to the individual, and if it works for you, then why change it?