I would not use it while breast feeding and I would avoid lotions other than aloe too. Your body can absorb things and they pass on to the baby. You can rub wheat germ oil on as that has lots of vitamin E and is safe.
There is no cream that can cure or prevent stretchmarks-which is damage to the skin at a cellular level. As a good habit, you should keep hydrated inside and out-drink lots of pure water and use a normally priced lotion to rub lightly into skin during pregnancy and breastfeeding. Mustela products are safe for breastfeeding mothers however.