When does hemoglobin level in term newborns typically reach its lowest point?

In term newborns, hemoglobin levels generally reach their lowest point between 2 to 3 months of life. This phenomenon is known as physiological anemia of infancy. After birth, infants experience a rapid decline in hemoglobin levels due to several factors, including the transition from fetal to neonatal circulation, the cessation of placental blood flow, and the relatively lower hemoglobin levels in newborns compared to adults. As newborns grow and their erythropoietic (red blood cell production) activity increases, hemoglobin levels gradually rise after reaching this nadir.

During the first week of life, while newborns may still have elevated levels of fetal hemoglobin, they are typically not at their lowest. At birth, hemoglobin levels are at their highest before this physiological decline begins. The period between 4 to 6 weeks can still be part of the declining trend after birth, but it's primarily within the first 2 to 3 months that the lowest hemoglobin concentration is observed, making this timeframe crucial in monitoring for possible anemia and ensuring appropriate follow-up cares.