Carboxyhemoglobin in umbilical cord blood and maternal smoking

Background: Smoking during pregnancy still exists in daily life but the effect on the newborn in the early stage of life is still unclear. This study investigates the normal reference range of carboxyhemoglobin (HbCO) in umbilical cord blood gas (UBG). Methods: A single center retrospective cross-sectional cohort study was performed with 1172 cases. We analyzed HbCO values in umbilical cord blood, maternal smoking, birth weight percentiles, duration of amenorrhea and maternal admission duration prior to delivery. Results: HbCO levels in newborns range from 0 to 7.7% with a mean of 0.6% (standard deviation 0.6). Newborns from women who smoked during pregnancy have a significant higher HbCO value compared to newborns from women who did not smoke. Birth weight is negatively correlated with HbCO (P=0.001). Conclusion: Our results show the normal reference range in this study is 0-1.2% for HbCO in the umbilical blood of newborns. Smoking prior to delivery leads to a higher HbCO value in the UBG sample of the newborn, a lower birth weight and may be potential harmful.