You should combine your dermaroller with a more targeted instrument such as a 1.5 mm dermastamp or the single needle. If you are prone to pigmentations, buy the single needle and precisely target just the stretch marks.
There is no other way to find out how your skin reacts to dermarolling than trying it on a small area of skin.
Also buy our 0.1% Tretinoin cream. Follow more or less the routine I describe here:
https://http://forums.owndoc.com/dermarolling-microneedling/stretch-marks-from-pregnancy/ Pricking does not harm the regular skin.
Hyperpigmentation can occur if you are really very prone to hyperpigmentations.
I will paste here my reply from another forum thread concerning pigmentations:
Sometimes, it is residual inflammation. Try this: buy a non steroidal anti-inflammatory such as Nurofen rapid capsules (it contains liquid ibuprofen). For sale in pharmacies (OTC). Prick the capsule and apply some of it at least twice a day on the pigmentation. It may sting.
And sometimes it is overproduced melanin pigment. Melanin is skin pigment that is normally present in the skin but unfortunately the skin often reacts to skin injuries by overproducing the pigment. Even very small skin disturbances, like a bug bite, can in some individuals result in the overproduction of melanin in that spot. What helps then is Tyrosinase inhibitors such as hydroquinone. They inhibit the enzyme that converts tyrosine to melanin. They do not remove existing melanin, they only prevent formation of excessive melanin in the future so you have to use them long term.
It can also be a combination of residual inflammation and melanin overproduction.
What sometimes helps (in both cases) are products that speed up the turnover of the skin - microneedling, acid peels, Tretinoin cream etc.