Smoking During Pregnancy Ups Preemie's "Cot Death" Risk

There are so many health-related reasons to quit smoking, and now researchers have added a new reason to that on-going list. This reason, however, has nothing to do with your heart or lungs instead it has to do with your babies.

A new research has found that premature infants whose mothers smoked during pregnancy may be at a significantly higher risk for sudden infant death syndrome (SIDS), sudden and unexpected death of an apparently normal infant that remains unexplained after an adequate autopsy.

The study released Friday by the University of Calgary found that smoking not only raises a mother's likelihood of having a preterm baby but also increases the infant's susceptibility to SIDS or cot death.

"Smoking during pregnancy is a double-edged sword with respect to SIDS," said Shabih Hasan, M.D., a staff neonatologist and professor in the department of pediatrics at the University of Calgary, and the principal investigator of the new study.

"Not only does it raise a mother's likelihood of having a preterm baby, who is already among the most vulnerable to SIDS, but it increases the infant's susceptibility to SIDS even further," Hasan said.

Due to publish in the September issue of the American Journal of Respiratory and Critical Care Medicine, the study by the researchers at the University of Calgary is the first-ever to investigate the effect of low oxygen and cigarette smoke exposure on infants' heart rate and breathing responses.

In order to explore the impact of cigarette smoke on premature infants' respiratory health and its relation to cot death, Hasan and colleagues recruited 22 preterm babies who had been spontaneously born between 28 and 32 weeks, with no other complicating respiratory factors.

Of the infants, twelve had mothers who had smoked five or more cigarettes every day in pregnancy, while the other ten infants’ mothers did not smoke during pregnancy.

All the infants were briefly given lower-than-normal oxygen levels to breath, to match the effects of breathing interruptions common in premature babies. The researchers found that babies born to smoking mothers showed increases in heart rate during the time of low oxygen supply, meaning their bodies were under greater stress when oxygen was low.

On the other hand, the blood oxygen levels in the babies of non-smokers recovered more swiftly than their counterparts. They even did not show such stress even when oxygen was low.

“This has clear implications for their risk of SIDS. Our study shows that pre-term infants make incomplete or delayed recoveries from interruptions to breathing." Hasan said. "There is increasing evidence that infants exposed to prenatal cigarette smoke are at high risk for developmental and behavioral disorders."

Sudden infant death syndrome, also known as crib death, fatal syndrome that affects sleeping infants under a year old, characterized by a sudden cessation of breathing and thought to be caused by a defect in the central nervous system.