I used Neals Yard Wheatgerm oil which is quite thick, brown, not particulary nice, but apparently is VERY nutrient rich.
Good to have EFA's too, which help to increase elasticity.
I also used almond oil (until po faced HV told me off), pure (you can eat it) vitamin E oil, both from Holland & Barrett.
AND I took homeopathic tablets - Calc fluor . I have unsightly pubety stretchmarks from around age 13, which I found very distressing when I was growing up . I'm not vain, I just wanted to try anything to stop my belly being covered in stripes....pleased to say something worked as I don't have any baby ones !
See this from Babycentre
How to prevent them
? Stretchmarks may in some cases be prevented by using a good aromatic oil daily from early on in pregnancy. Here's a recipe to try: fill a dark glass bottle with 50ml wheatgerm oil, or a mixture of wheatgerm and almond oil for a thinner solution. Add 3 drops of lavender essential oil and 15 drops of the neroli essential oil. Massage daily after bathing.
? You can also try taking a daily supplement of vitamin E to help increase skin elasticity.
? Homeopathy has also been known to help. Take Calc fluor 6X three times daily for a week starting in early pregnancy; continue taking on alternate weeks for the rest of your pregnancy. This remedy will help to increase the tissue elasticity of dry or delicate skins.
? Apply pure vitamin E oil locally to prevent or reduce stretch marks. Continue using regularly until after the birth.