Early onset of otitis media has been identified as a risk factor for recurrent otitis media and chronic otitis media with effusion. No studies to date, however, have specifically examined the relationship between innate and early factors, and onset of otitis media in the first few months of life. It will also be the first prospective study to use a biochemical measure of exposure to passive smoke and its effect on early onset otitis media. The study is designed to follow 700 infants from birth to two years of age to examine the relationship between prenatal nutrition and lifestyle factors, early infant host and environmental factors, and development of otitis media in the first six months of life. The relationship between these exposures and recurrent and chronic otitis media will also be explored. The infants in this study will be born to a cohort of women planning their first pregnancy who are currently enrolling in a NIH- funded study, called the Diana project, which is investigating the effects of preconception and prenatal nutritional, biological, psychosocial and lifestyle factors on infant birth weight for gestational age. The collaboration between the two projects will greatly reduce the cost required to conduct the proposed study through data sharing of maternal exposures. Additional data on early host and environmental factors (e.g. immunoglobulin and complement levels, exposure to passive smoke, day care attendance) will be collected. After controlling for confounders, the effects of innate and early infant factors on early otitis media will be determined using both regression and survival methods.