▁risk ▁factor ▁for ▁AS D . ▁In cre ased ▁risk ▁of ▁aut ism ▁has ▁also ▁been ▁linked ▁to ▁rapid ▁" catch - up " ▁growth ▁for ▁children ▁born ▁to ▁moth ers ▁who ▁had ▁un he alth y ▁weight ▁at ▁conception . ▁ ▁A ▁large ▁ 2 0 0 8 ▁population ▁study ▁of ▁Swedish ▁parents ▁of ▁children ▁with ▁aut ism ▁found ▁that ▁the ▁parents ▁were ▁more ▁likely ▁to ▁have ▁been ▁hospital ized ▁for ▁a ▁mental ▁dis order , ▁that ▁sch iz op hren ia ▁was ▁more ▁common ▁among ▁the ▁moth ers ▁and ▁f athers , ▁and ▁that ▁de pression ▁and ▁person ality ▁dis orders ▁were ▁more ▁common ▁among ▁the ▁moth ers . ▁ ▁It ▁is ▁not ▁known ▁how ▁many ▁sib lings ▁of ▁aut istic ▁individuals ▁are ▁themselves ▁aut istic . ▁Several ▁studies ▁based ▁on ▁clin ical ▁samples ▁have ▁given ▁quite ▁different ▁estimates , ▁and ▁these ▁clin ical ▁samples ▁differ ▁in ▁important ▁ways ▁from ▁samples ▁taken ▁from ▁the ▁general ▁community . ▁ ▁Aut ism ▁has ▁also ▁been ▁shown ▁to ▁cluster ▁in ▁urban ▁neighborhood s ▁of ▁high ▁so cio e conom ic ▁status . ▁One ▁study ▁from ▁California ▁found ▁a ▁three ▁to ▁four fold ▁increased ▁risk ▁of ▁aut ism ▁in ▁a ▁small ▁ 3 0 ▁by ▁ 4 0   km ▁region ▁centered ▁on ▁West ▁Hollywood , ▁Los ▁Angeles . ▁ ▁G ender ▁differences ▁ ▁Boys ▁have ▁a ▁higher ▁chance ▁of ▁being ▁diagn osed ▁with ▁aut ism ▁than ▁girls . ▁The ▁AS D ▁sex ▁ratio ▁aver ages ▁ 4 . 3 : 1 ▁and ▁is ▁greatly