I have eczema, not psorasis, so not sure if it is the same, but my gets so much worse in pregnancy. That was when my huge flare up happened, when i was pg with DS. Apparently like 95% of peoples gets better & virtually goes away in pregnancy, and the others of us, well, life sucks huh! My dermo said it was also due to the slightly higher body temp during pregnancy that dries to skin out more.

In terms of UV therapy, i find it only improves once i hit over 7 mins, and when i go at least twice a week. I normally only have to keep up that dosage for maybe 4 weeks along with other stuff to basically go into remission. It's getting to the 7 mins that takes ages.