I also have vitiligo, and while I have no special medical knowledge, I can speak from personal experience.
I am white, and my skin pigment was perfectly normal when I was a child. My normal skin tone was a medium shade; every summer I tanned to a medium golden brown (this was back in the days before skin cancer, you see :smack: ). When I was around 17 or 18, I noticed that the area around my cuticles on several fingers looked pale. Somewhere about that time, I also noticed a couple of small pale patches on my knuckles and near my ankles. This is how it stayed until I was 28 and got pregnant for the first time.
During my pregnancy, I lost pigment in small patches all over my hands, forearms, and lower legs. By the end of the pregnancy, my hands were almost completely white. The pigment loss slowed dramatically after the baby was born, but it was quite noticeable, and if I wore short-sleeved shirts, I got stares and small children asking me what happened to my arms. The spots on my legs were less noticeable as long as I stayed out of the sun. Whenever I got sun exposure, the pigmented places would get very dark, and it seemed to me that there were soon more unpigmented spots.
When I got pregnant the second time, the pigment loss started up again faster than before. By the time my second baby was a few months old, the skin on almost all of my body was completely unpigmented. My hair retained pigment, and there are a few brown spots here and there, but otherwise I just look extremely pale. I was diagnosed with thyroid disease shortly after my second child was born. My doctor believes that the thyroid deficiency, coupled with pregnancy hormones, spurred the progress of the vitiligo. I’m just happy that my skin tone is fairly uniform nowadays, and it’s always amusing for the children to be able to trace the veins in my legs.
My mother and grandfather also had the disease (my doctor called it a “genetic virus”, although I still don’t quite understand the implications of that), and I have four cousins on my mother’s side who have very noticeable cases. My aunt, their mother, didn’t show any signs, nor does my brother or their sister.
I doubt that Jackson’s condition was affected by pregnancy, but from my experience, I do know that the effects usually worsen over time. I don’t know of any effective skin whitening treatment - at least, my doctor never offered me any when I was splotchy all over and people were asking my how I sustained my “burns” - and I can readily believe that his skin is mostly non-pigmented, although it also looks like he applies pancake makeup rather liberally.