To the Editor: In a meta-analysis of prospective population-based studies, Mary Cannon, M.D., Ph.D., M.R.C.Psych., et al. (1) reported that three classes of complications were "significantly associated with schizophrenia: 1) complications of pregnancy (bleeding, diabetes, rhesus incompatibility, preeclampsia); 2) abnormal fetal growth and development: (low birth weight, congenital malformations, reduced head circumference), and 3) complications of delivery (uterine atony, asphyxia, emergency Cesarean section)" (p. 1080). Thus, there are no less than 10 factors of etiological significance for schizophrenia. But how could so diverse a list of factors all have the same effect? If any one were relevant, why would it not stand out, given proband versus healthy comparison groups of 1,923 and 527,925 births, respectively?