I've only ever used cocoa butter. I am pregnant with my second kiddo and I have zero stretch marks on my tummy 

Genetic so practice your mum and grandma didn't have them Try nor to itch where it stretchs Also if you scar easy there's no stopping them

I oil 3x a day with coconut oil and olive oil. Right now I try almond oil:) Pretty much any oil helps to smoothen your skin. Everyone around me incl. my doc and midwife are amazed by my belly. They all say it's so smooth and beautiful:)) Mind that my mom has stretch marks bc no one told her to oil. Give it a try.

I use bio oil, I'm 39 weeks and it's worked pretty well. :) only 2 small stretch marks. The rest are hives, make sure you don't itch! I really made sure not to!

Sorry, but this is more of a genetic thing than a maintenance thing. Ask your mother if she got stretch marks during pregnancy. Your answer will probably (but not definitely) be the same as hers. 

Drink lots of water to keep your skin hydrated. I'm 24 weeks without a single stretch mark yet.