Early-Life Environmental Determinants of Allergic Conditions in Children with Atopic Heredity: A Single Center Cross-Sectional Study from Bulgaria

Background: Allergic diseases in early childhood are influenced by genetic predisposition and modifiable early-life exposures, including epigenetic mechanisms. Understanding the interplay between environmental factors and allergy development in children with atopic heredity is critical for prevention strategies. Objective: To investigate the associations between selected early-life environmental exposures and the development of allergic conditions in children with a positive family history of atopy. Methods: A cross-sectional study was conducted among 120 children aged 2 years (±5 months) with atopic heredity, recruited at the Medical University of Varna, Bulgaria (2017–2020). Data on sociodemographic background, prenatal exposures, birth mode, feeding practices, pet contact, daycare attendance, and infectious burden were collected via structured questionnaires and medical records. Allergic outcomes (food allergy and atopic dermatitis) were physician-confirmed. Statistical analyses included t-tests and chi-square tests. Results: Food allergy was diagnosed in 23.3% and atopic dermatitis in 21.7% of participants. Formula feeding was significantly more common in children with food allergy (66.7% vs. 38.1%; p = 0.020). A lower maternal pregnancy experience score was significantly associated with both food allergy (p = 0.021) and overall allergic outcomes (p = 0.004). Indoor smoking was more common in households of non-allergic children (p = 0.034). Children with food allergy had significantly more rhinopharyngitis episodes (p = 0.014) and longer infection duration. Higher gastroenteritis frequency and hospitalization rates were also noted in food-allergic children. Conclusions: In children with atopic heredity, early formula feeding, prenatal maternal stress, and infection burden were associated with increased risk of allergic conditions. This study underscores the importance of early-life psychosocial and environmental influences, possibly mediated by epigenetic mechanisms, in the development of childhood allergies. These findings highlight novel targets for early prevention and warrant further longitudinal research.