Wee Dot> In the case of a young girl, you might just be lucky and she might just be able to get her skin to cooperate and heal, since she will still be growing for some time.
An old remedy is pure cocoa butter cream. Not the stuff that is inexpensive, with lots of additives and scents to make it smell better. I mean only the _pure cocoa butter cream_ that will smell somewhat like very strong bakers dark chocolate. It will be slightly pungent and not sweet at all.
Go to a drug store or a pharmacy section in your favorite store. Read the ingredients and even ask the pharmacist if he has some in stock for over the counter sales, or if he can order it, or if he knows where it is located in the store. He or she will most likely also suggest something
for your daughter's young stretch marks.
Now, your daughter will need to apply this stuff to her stretch marks over the course of several years. As she grows, she will fill out the skin and the cocoa butter cream will help in so many ways. It is believed to also increase melanin distribution in the area of the stretched skin.
It is so much better for a youth to try to tackle this issue while young. While adults can not get rid of stretch marks because they have stopped growing ( unless the are expanding, but that has to do with weight issues and not actual progressive human growth in adolescents)
Some sunlight will also help in bringing out the melanin, unless she is photosensitive or burns easily, or has very pale white skin. If she has average colored skin that can handle sun, or skin that can tan, or skin that tans easily, or if she has olive skin, or African skin, or mediterranean skin, she will do well with some sunlight and the pure cocoa butter cream. She can also use a skin beneficial oil. I am not suggesting that she over-do a tanning booth. I am not suggesting that she all out burn herself in some way with the sun or a tanner. I am not suggesting that she become a permanently tan person by over doing tanning in the sun or in a booth.
I am only suggesting that she can boost the coloring in the stretched skin area, and since she is a youth, her legs could get longer, and she might use the stretch marks for growth in those areas that would be adult and permanent, it would reduce the appearance of the stretch marks as they will not only fade, but they will involute, hollow out, become indentations and
thus more obvious in adults.
I hope this helps her to heal her skin and help her to grow to adulthood with decreased appearance in the stretch mark areas, and possible recovery to health skin, with less possibilities of additional stretch marks in those areas, because she is only 12, this could really work as a long term reduction and eventual resolution of her "growing pains" type of stretch mark in a young pre-teen female.
This added to the posts about good nutrition will do wonders for your daughter as she grows into a young woman, 12 is the age that her hormones should start really kicking in, and I suspect it might be having a cause and effect reaction in her right now.
We can do so much for children and their health and skin if we catch things right away. They have such powers of recuperation during their growth spurts that you can don wonders for her and her ability to heal as she grows up into an adult.
Best wishes to your little darling daughter.
(12 can be such an awkward age for a girl)
(With so many changes going on it's easier to start them on lifelongs habits now.
Just before their peer group takes over and they become a teenager)