Ask her Mum & aunts (from Mum's side) & if she has any sisters with kids.... Well ask them too, if they have stretch marks she will likely get them & if they dont then she may not get any!

I didnt use anything religiously, I just birthed my 3rd baby & dont have any stretchmarks, but neither of my sisters have any stretchmarks nor does my Mum...

Nonw of us used anything in particular except my Mum whose best mates Dad was a Chemsit & he gave her pure lanolin in a tin (direct from sheeps back) which stunk to high heavens but she massaged that in daily & never got a mark with 3 kids!

But I think it's more genetic than anything else!!!