The prevalence of asthma and allergic diseases in childhood has increased in several industrialized countries since the second half of the twentieth century. In some countries, the prevalence is still rising, although in others it seems to have plateaued or even decreased. It has been suggested that environmental factors operating prenatally and in early life affect the development of asthma and allergic diseases. Particularly changes in microbial exposure are proposed to play an important role in the development and maturation of the immune system. Thus, the factors that affect microbial exposure, such as mode of delivery and the use of antibiotics, may influence the development of asthma and allergic diseases. Several studies have explored the associations between perinatal factors and children's use of antibiotics and the risk of asthma, with inconsistent findings. The present review article will be focused on the important findings related with factors responsible for above allergic reactions along with asthma in young infants. Also, the influence of cow milk intake will also be taken in account to cover the aspect of cow milk induced allergies and asthma in infants.