So when you have a child with DS, you suddenly become much more aware of milestones, when they are "supposed" to be met, and where your child is compared to that date. Then for me anyway, the when became much less important than meeting them eventually has become. So here is a brief rundown of my favorites when it comes to milestones...
Ok, I like the Gross Motor Book from Woodbine - http://www.woodbinehouse.com/synopsis.asp_Q_product_id_E_0-933149-81-6 - it really is clear and shows the steps in development. I didn't try to read the whole thing, just what was coming up next (I try to stay a step ahead of her, lol.)
As for development in terms of weight and length, I really like this MedCalc interactive growth charts - on the right hand side you see a box you can click for the Down syndrome growth charts - I like comparing the typical to the DS ones.
I also like to keep track of the typical developmental charts - I really try as best as possible to disregard the ranges for meeting those milestones, but like to know "what" as much as "when." I was given a HELP chart by our hospital - there are three of them and they are very comprehensive. They cover social, gross motor, cognative fine motor, self help skills, etc. I asked our EI folks if they could get them for me, and they did free of charge. You can also order them here:
I review the HELP charts every 3-6 months or so to make sure I know the next things developmentally she should/could be doing, and put activities with those sorts of things in front of her to do. I also use the next batch of developmental milestones as a basis for goals for our ISFPs (I'm a bit of a control freak when it comes to ISFPs - I tend to write them with what I think she and we can help her to achieve, and let them rewrite them how they like them.)
Finally, I really like the DownsEd DS Milestone charts - I think they are most comprehensive -
As for the Babies with Down Syndrome book http://amzn.to/91eWPK - I have it. There are things I like about it, and things I don't like about it. I think the new version is much better than the old, but I'm still a bit lukewarm. I think it was too much information for me when I first got it. Just my personal feelings about it.