Gray baby syndrome is a syndrome in which the use of chloramphenicol by the pregnant mother during pregnancy, especially at the end of pregnancy and within 24 hours of delivery, causes vomiting, rapid or irregular breathing, grayish skin, hypothermia, weakness, and even death in the newborn baby born. The fetus can be affected by many external factors during its development, and some drugs can also pass through the placenta causing fetal dysplasia and even life-threatening. As a broad-spectrum antibiotic, chloramphenicol can enter the fetus through the placenta and affect the development of the fetus. Premature babies and newborns have imperfect liver and kidney function, and have less uridine diphosphate glucuronosyltransferase, which has a lower detoxification capacity for chloramphenicol and a poorer renal excretion capacity, which can easily cause the accumulation of the drug in the body and lead to gray baby syndrome. Therefore, chloramphenicol is absolutely prohibited for pregnant women, preterm infants and newborns.