These infections may occur at delivery time and also from external sources after birth. In case of utero infection, infection may occur before birth consequences depend on time of infection, spontaneous abortion, premature birth. Common viral agents are herpes virus, hepatitis B, unless virus transmits transplacentally. Bacterial agents include streptococci, enteric gram negative organisms. The impact factor of journal provides quantitative assessment tool for grading, evaluating, sorting and comparing journals of similar kind. It reflects the average number of citations to recent articles published in science and social science journals in a particular year or period, and is frequently used as a proxy for the relative importance of a journal within its field. It is first devised by Eugene Garfield, the founder of the Institute for Scientific Information. The impact factor of a journal is evaluated by dividing the number of current year citations to the source items published in that journal during the previous two years.