Final answer:
Infants with sickle cell disease are asymptomatic until 8-10 weeks after birth due to differences in fetal hemoglobin, physiological changes, and increasing demands on the newborn's body.
Step-by-step explanation:
Infants with sickle cell disease are generally asymptomatic until about 8-10 weeks after birth due to several factors. Firstly, fetal hemoglobin, which is different from adult hemoglobin, can bind with oxygen at lower pressures, allowing it to bind with oxygen from the mother's blood in the placenta. Secondly, the physiological changes observed in sickle cell disease, such as excessive hemolysis, physical exertion, and leukemia, take some time to manifest. Lastly, the symptoms of sickle cell disease, like anemia, weakness, and shortness of breath, become more prominent as the newborn grows and their body's demands increase.