THE PREVALENCE OF FOOD ALLERGY HAS SIGNIFICANTLY INCREASED OVER THE LAST THREE DECADES, NOW AFFECTING 1 IN 13 CHILDREN IN THE UNITED STATES. ALLERGIC DISEASES ARE CHRONIC AND CAN SIGNIFICANTLY AFFECT QUALITY OF LIFE; HOWEVER TO DATE, MOST PRIMARY PREVENTION STRATEGIES HAVE BEEN UNSUCCESSFUL. EVIDENCE INDICATES THAT MATERNAL DIET AND ENVIRONMENT DURING PREGNANCY AND LACTATION PLAY A SIGNIFICANT ROLE IN EARLY IMMUNE DEVELOPMENT AND AN INFANT'S RISK FOR ALLERGY. IN PARTICULAR, MATERNAL EXPOSURE TO A TRADITIONAL FARMING ENVIRONMENT HAS BEEN CONSISTENTLY ASSOCIATED WITH REDUCED RISK OF CHILDHOOD ALLERGIC DISEASES.YET, THE MECHANISMS BY WHICH THIS FARM LIFE PROTECTIVE EFFECT ARE CONFERRED TO THE INFANT THROUGHOUT THE PERINATAL PERIOD REMAIN UNCLEAR. THE INCREASED MICROBIAL EXPOSURE AND DIFFERENT DIETARY PRACTICES ON FARMS MAY INFLUENCE THE MATERNAL GUT MICROBIOME DURING PREGNANCY, WHICHHAS BEEN ASSOCIATED WITH IMMUNE AND ALLERGY DEVELOPMENT IN PRECLINICAL STUDIES BUT HAS NOT BEEN ASSESSED IN FARMING POPULATIONS. SUBSEQUENTLY DURING THE POSTNATAL PERIOD, THE PROTECTIVE FARM EFFECT MAY BE CONFERRED TO THE INFANT THROUGH BREASTFEEDING. HUMAN MILK CONTAINS A DIVERSE PROFILE OF COMPONENTS THAT SUPPORT INFANT DEVELOPMENT, SOME OF WHICH HAVE BEEN SHOWN TO BE INFLUENCED BY MATERNAL DIET AND GEOGRAPHY. THOUGH BREASTFEEDING IS RECOMMENDED FOR PREVENTION OF ALLERGY, STUDY FINDINGS HAVE BEEN MIXED, POTENTIALLY DUE TO INTERPERSONAL VARIATION IN COMPOSITION. ADDITIONALLY, HUMAN MILK COMPOSITION HAS NOT BEEN WELL CHARACTERIZED IN POPULATIONS AT HIGH- AND LOW-RISK FOR ALLERGIC DISEASE AND FACTORS REGULATING COMPOSITION ARE GENERALLY NOT WELL UNDERSTOOD. HEREIN, THE OVERALL GOAL OF THIS PROJECT IS TO ADVANCEUNDERSTANDING OF HOW MATERNAL DIET AND ENVIRONMENTAL EXPOSURES INFLUENCE THE PRENATAL MICROBIOME AND HUMAN MILK METABOLOMEAND RELATE TO DEVELOPMENT OF INFANT ALLERGIC DISEASE IN FARMING AND URBAN COMMUNITIES. THIS PROJECT WILL LEVERAGE DATA AND SAMPLES FROM AN ONGOING LONGITUDINAL BIRTH COHORT STUDY OF MOTHERS AND INFANTS FROM THE OLD ORDER MENNONITE (OOM) AND URBAN/SUBURBAN ROCHESTER, NY COMMUNITIES, WHO ARE AT LOW- AND HIGH-RISK FOR ALLERGIC DISEASE, RESPECTIVELY. THE OOM RESIDE IN THE COUNTRYSIDE OF WESTERN NY AND ADHERE TO A TRADITIONAL FARMING LIFESTYLE CHARACTERIZED BY EXPOSURE TO UNPASTEURIZED DAIRY PRODUCTS (MILK, YOGURT, BUTTER), CONTACT WITH LIVESTOCK, LARGE FAMILIES, INFREQUENT ANTIBIOTIC USAGE, AND LOW RATES OF CAESAREAN BIRTH. THE ROCHESTER GROUP CONSISTS OF URBAN/SUBURBAN MOTHERS WITH AN INFANT THAT HAS A PARENT OR SIBLING WITH ALLERGIC DISEASE. WE WILL ASSESS HOW MATERNAL DIETARY INTAKE AND ENVIRONMENTAL EXPOSURES (RESIDENTIAL ENVIRONMENT AND EXPOSURE TO LIVESTOCK, PETS, STABLES, PESTICIDES, CLEANING PRODUCTS, ETC.) INFLUENCE THE MATERNAL GUT MICROBIOME DURING PREGNANCY AND METABOLITES IN BREAST MILK AS WELL AS HOW THEY RELATE TO INFANT ALLERGIC DISEASE OUTCOMES AT 1 YEAR OF AGE, WITH FOOD ALLERGY BEING OF PRIMARY INTEREST.ULTIMATELY, OUR GOAL IS TOLAY THE GROUNDWORK FOR DEVELOPMENT OF MATERNAL PERINATAL NUTRITION AND LIFESTYLE INTERVENTION STRATEGIESTO REDUCE PREVALENCE OF ALLERGIC DISEASES IN CHILDHOOD.