While retrospective studies of language have shown fairly clear and consistent results, prospective studies have been more equivocal. Phonological processing deficits at age 14 years were related to prenatal alcohol exposure levels in a long-term prospective study (Streissguth, Barr, et al., 1994). Another series of prospective studies found lower levels of alcohol exposure to be associated with significantly lower language comprehension and expression in children at 13-months (Gusella & Fried, 1984), 2 years (Fried & Watkinson, 1988), and 3 years (Fried & Watkinson, 1990). However, within the same cohort of children, deficits in language abilities were not detected later at 4 (Fried & Watkinson, 1990), 5, and 6 years of age (Fried, O'Connell, & Watkinson, 1992), and another prospective study found neither expressive nor receptive language impairments in children ages 1, 2, and 3 years (Greene, Ernhart, Martier, Sokol, & Ager, 1990). A more recent study also found no association between low levels of alcohol exposure and parent reports of language delay at age 2 years (O'Leary, Zubrick, Taylor, Dixon, & Bower, 2009). A possible explanation for these discrepancies may
