Critically ill neonates, whether premature or those born closer to full-term gestation, can have adverse outcomes following untimely exposure to many physiological and other potentially pathogenic stimuli in utero and after birth. [1][2][3] In many organ systems, even minor alterations in the course of maturation can cause abnormalities. 4,5 Carefully designed studies are needed to extrapolate the experience from one part of the world to another; 6,7 there are important genetic, infectious, and cultural differences that might affect outcomes. However, in many situations, there are vertical influences where information about maternal health can help us in understanding neonatal disease and in predicting its outcomes. 8 We have long believed that the fetus grows in a sterile uterovaginal tract. 9 However, recent studies have identified bacterial flora in the birth canal. 10 The impact of this colonization on a fetus developing in utero is still unclear, but there is a possibility that the presence of these bacteria on mucosal surfaces might alter perinatal outcomes. 11 The effect on the developing fetal immune system also needs study, particularly with emerging information about many subclinical infections prevalent in many parts of the world. 12,13 There is a need for improved understanding of the impact of these infections on the developing immune system.In addition to the bacterial flora, nutrition is another important stimulant for the rapidly growing organs, be it the central nervous system, immunity, or the endocrine system. 14 The nutritional experiences of the newborn infants may have lifelong effects. 15 Human milk contains fats in high concentrations, which seem to be important as a source of energy and in maturation of the neurological and mucosal immune systems. 16,17 Milk fat content and composition are highly dynamic parameters in early infancy, and need careful analysis. 18 However, despite increasing awareness about the importance of human milk, we also now know about the factors that may curtail its availability. Mothers of infants who are critically ill experience a high degree of anxiety, and may not always able to provide milk for their infants. 19,20 The availability of human milk may also be limited in situations such as maternal illness, ongoing drug therapy, or substance abuse. 21 In these situations, human milk banks can be an important resource but there are many restrictions-natural and human-created. 22 We have been able to make important progress in the treatment of many life-threatening neonatal illnesses. 23 These advances have not only reduced neonatal deaths, but have also facilitated major societal changes; fewer neonatal deaths have helped in reducing the total number of pregnancies per woman as she is reassured about the number of surviving infants. Fewer pregnancies have helped reduce maternal mortality. 24,25 In the Newborn, we aim to cover problems that a baby might develop in utero, the perinatal period, following birth, and the implications of these abnormalities during the ...