The earlier infections occur in intrauterine life the more severe are they. When the infection develops during embryogenesis, the lesions are much more serious, sometimes causing disruptions (malformations). At this time the organs are not completely formed and microorganisms may interfere with organogenesis to such an extent that the development of the functions necessary for viability become impaired. Infection acquired in utero may result in resorption of the embryo, abortion, stillbirth, neonatal death, intrauterine growth retardation (IUGR), or prematurity. The infected newborns commonly are apparently normal at birth but they may develop a late onset disease. Otherwise, neonates presenting symptomatology may derelop untoward sequelae.