The Georgia PRAMS dataset contains information on maternal influenza vaccination (during any trimester); maternal attitudes, behaviors, and experiences before, during, and shortly after pregnancy; and newborn birth certificate data, including birth date and birth weight. Prematurity was defined as clinical estimate of gestational age (at birth) as less than 37 wk. Newborns with birth weight below the10 th percentile for their gestational age were considered to be SGA. We used gender-specific reference values for the US published by Oken at al. [9] to assign SGA (yes/no) categories.