It's a pity that there are no informations at all.
I remember another discussion about elfin gestation period. There was an agreement, that the long time and not showing belly during the first half has to do with the developement of the magic abilities.
When this is true, Troll should have a clearly shorter pregnancy.
On the other hand - Trolls are big. Trolls live very long. Bigger size and longer life normally mean longer gestation periods for animals on earth. Can have an influence on Troll pregnancy, too.
Trinket looks like three to five years for me when we meet her first. Well, she's walking and speaking without difficulty - at least four years, I guess.
Easter EggQuest 2012 found