Premature infants whose mothers smoked during pregnancy may be at even higher risk for sudden infant death syndrome (SIDS) than preemies whose mothers did not smoke, according to new research out of the University of Calgary said Shabih Hasan, M.D., a staff neonatologist and professor in the department of pediatrics at the University of Calgary. The research will be published in the first issue for September of the American Thoracic Society's American Journal of Respiratory and Critical Care Medicine.
To analyze the effects of cigarette smoke exposure on preterm infants' respiratory health and their risk of SIDS, the researchers recruited 22 preterm infants who had been spontaneously born between 28 and 32 weeks with no other complicating respiratory factors. Twelve of the infants had mothers who had smoked five or more cigarettes every day in pregnancy. The mothers of the other ten infants did not smoke during pregnancy.
There were significant differences between the two groups of preterm babies with respect to heart rate and recovery period. The cigarette-smoke exposed infants showed increased heart rate during the hypoxemic period compared with their baseline values, but there was no difference in heart rates was observed in control infants, indicating that the oxygen depletion put their bodies under more stress than the control groups.
"Our study shows that preterm infants make incomplete and/or delayed recovery from interruptions in breathing," said Dr. Hasan. "This has clear implications for their risk of SIDS. But there is even still another reason for concern even after the risk of SIDS has passed. Inability or delayed recovery from repeated low oxygen episodes can also be detrimental to brain development. There is increasing evidence that infants exposed to prenatal cigarette smoke are at high risk for developmental and behavioral disorders."
Regardless of the mechanism, the study has immediate clinical relevance: "Since preterm infants continue to have significant cardiorespiratory events after discharge from the hospital, our study may help identify the infants at risk for attenuated recovery from hypoxemic episodes while at home," said Dr. Hasan. "Furthermore, it might help distinguish the infants, who will arouse in response to hypoxemia. The infants identified to be at risk can subsequently be further investigated and/or monitored at home."
