How sad that these gals can't seem to tap into their feelings enough to put it into words! I am step-mom to a teen mom, so this one speaks to me (she has a lot of other issues, too).
You might want to check out sites that have writing prompts. One I like to use is http://www.scrapyourstories.com/lifewriting.htm
Another idea could be to search sites that have page galleries (like creativememories.com
and show the girls really nice pages that revolve more around the journalling than the "bling". Maybe they will be inspired?
One more idea, while I think of it. You could do a theme class, where they are forbidden to use photos for one page. The page could have a theme, and they could all bounce ideas off of each other. I did one that was "Things I will miss when you grow up". I put a list of things like baby kisses, being able to fix owies with a hug and a kiss, etc. Another page idea could be "The story of your birth". The girls could tell about their trip to the hospital, how long labor took, how they felt when they got to see baby for the first time. Or they could write "Dear Baby" letters entitled "My Wish for You". They could write a letter to baby telling him/her what their hopes and dreams are for baby.