Fetal hemoglobin levels in sids

To the Editor: The paper by Zielke et al.¹ concluded that there were normal levels of fetal hemoglobin in infants with sudden infant death syndrome (SIDS), as compared with controls. This was at variance with our data² showing increased levels of fetal hemoglobin in victims of SIDS. It is our interpretation that this discrepancy could be due to the lack of information about the correct gestational ages of the infants in the study by Zielke et al. Several studies have shown that the level of fetal hemoglobin declines as a function of postconceptional rather than postdelivery age.^{3 4 5} Zielke et al.