Prospective longitudinal birth cohort studies present an opportunity to examine temporal relationships between early-life exposures (i.e. prenatal, pregnancy, and early postnatal exposures) and multiple health and non-health related outcomes including mortality, morbidity, and socioeconomic position. It is well documented that exposures that occur early in life, including genetic, environmental, socioeconomic, and lifestyle factors, may have long-lasting effects on growth, development, and health outcomes throughout an individual's entire life course (Lynch & Smith, 2005). Thus, data on exposures during pregnancy and early childhood are valuable and may provide clues to the etiology of long-term outcomes.