The rise in asthma and allergic disease in recent decades, with accompanying morbidity and healthcare costs, has placed these conditions on the forefront of public health challenges. Allergic disease manifests itself shortly after birth, suggesting that disease development may commence already during fetal life. The early origins of these conditions and the concomitant changes in dietary habits have led to the formulation of several hypotheses relating dietary intake during pregnancy to deviant developmental adaptations in the fetal immune system and lung growth. These hypotheses are further supported by the demonstrated involvement of many nutrients, including fatty acids, antioxidants, and food allergens, in immune system function and maturation. Understanding the potential in utero influence of these nutrients on child allergic disease risk will provide a unique window of opportunity for early prevention by guiding women and their children to better health.