Blattner RJ. J Pediatr 1958;52:620-6 As little as 50 years ago, the importance of intrauterine infection as a cause of damage to the fetal central nervous system (CNS) was not widely appreciated. Autopsy studies on large series of patients identified only syphilis as a relatively common etiology of intrauterine and early postnatal CNS damage. In 1957, Edith Potter described the clinical pathological correlation of intrauterine cytomegalic inclusion body disease (CMV) due to placental transfer of viruses. It was recognized that human “salivary gland virus,” rarely responsible for overt illness in mother, could cause severe or fatal disease when transferred placentally to the fetus. Examination of the urinary sediment for inclusion bodies was the only available diagnostic procedure. We now realize that intrauterine infections, both systemic and involving the CNS, are a frequent and important cause of morbidity and mortality in the neonatal period. As many as 2% of fetuses are infected in utero by viral, bacterial, fungal, or protozoal agents. The acronym TORCH is widely used, although it has recently been maligned for its simplicity and lack of specificity. Congenital CMV infection is the most common intrauterine infection in developed countries, affecting 0.2% to 2.2% live neonates. Contemporary obstetrics involves first and second trimester ultrasound examinations, which can reveal abnormalities that suggest possible intrauterine infections, including intracranial calcifications, hydrocephalus, hyperechoic bowel, and intrauterine growth restriction. There is great variability in the clinical specificity and yield of algorithms used to evaluate these patients. Thankfully, a variety of microbiological and molecular tools with a high degree of diagnostic specificity are now available. Potter's report indicated that transplacental fetal infection often went undiagnosed during pregnancy because the mother was asymptomatic or had nonspecific signs and symptoms at the time of acute infection. We now appreciate not only the frequency of these important infections but also the importance of the stage of gestation at which infection occurs and the risk of adverse outcome. Nowadays, the obstetric standard of care is to screen all pregnant women for rubella, syphilis, hepatitis B, group B streptococcus, Chlamydia, and gonorrhea (with some states also screening for HIV), the most common and preventable perinatally acquired infections. Examination of the placenta also is recommended when infection is being considered as a causal or contributing factor to preterm delivery, fetal tachycardia, maternal signs of chorioamnionitis, neonatal intensive care unit admission, stillbirth, fetal birth defects, or abnormalities in intrauterine growth.