Hasan proposed smoking prevention in schools to lower SIDS rates.
courtesy Calvin Sun

Pregnant smokers increase SIDS risk

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A new study led by neonatologist and professor of pediatrics at the University of Calgary Dr. Shabih Hasan suggests that premature infants whose mothers smoked while pregnant are more likely to die of Sudden Infant Death Syndrome than those of non- smoking mothers.

The study is the first to analyze the effects of cigarette smoke exposure on the duration and recovery of breathing pauses and oxygen saturation levels in preterm infants.

According to Hasan, placing preterm infants with smoke exposure in higher temperatures slows their breathing even further and puts them at a much higher risk for SIDS.

"We first tested those hypotheses on an animal model which was developed in our lab," said Hasan. "We showed that the exposure to cigarette smoke with low oxygen decreases deep breathing responses and the rat pups start to gasp and the breathing fails. If you increase the temperature, they gasp even more and recover very, very slowly."

Twenty-two infants born between 28 and 36 weeks of gestation were carefully studied at the neonatal units of the Rockyview General Hospital and the Foothills Medical Centre. Of these, 12 babies were born to mothers who smoked five or more cigarettes daily during their pregnancies while the other 10 belonged to non-smoking mothers.

Throughout the experiment, respiratory rate, recovery response time, interruptions in breathing, periods of wakefulness, oxygen saturation in the blood, nasal airflow, chest and abdominal movements and heart rate were monitored. Additionally, the team recorded feeding, assessments and medication administration routines throughout the day.

Results showed that spontaneous recovery in cigarette-smoke-exposed infants was increasingly delayed in comparison to babies with good health. In addition, the heart rates of the infants continued to climb as compared to healthy infants.

Hasan said exposure not only causes complications for humans in their infancy, but for adults as well.

"The fetuses, which are exposed to cigarette smoke before birth, don't grow as well and they're smaller at birth," said Hasan. "When you're smaller at birth, it puts you at a much higher risk for hypertension, coronary artery disease, diabetes and other endocrine problems and early death as adults."

He added the chances of asthma, severe ear infections and developmental and behavioural problems are also increased.

Sarah Spensley, a non-smoking mom who agreed to participate in the study after her daughter Leah was born eight weeks premature, said she and her husband wanted to help researchers gather more information about SIDS.

"If [smoking mothers] have already been affected by it, I hope they can take this information and use it, and hopefully quit smoking before they have any more kids," said Spensley.

Leah, now three and a half, was born with apnea, a common lapse of breathing in premature infants. Spensley says as a result of her premature birth, Leah lagged behind in growth and proper motor skills. Today, it's a different story for Spensley's little girl, who functions like an average toddler.

The American Journal of Respiratory and Critical Care Medicine claimed earlier this month that SIDS continues to be the number one cause of infant deaths beyond the neonatal period. Three babies die of SIDS each week, according to Health Canada.

There may not be a way to predict or prevent SIDS from happening, however, parents are strongly advised against substance abuse, cluttered sleeping areas, placing babies on their stomachs or their sides and overheating them with layers of clothing.

"What I would really like to start and may not be able to accomplish is the re-examination of smoking prevention in school students," said Hasan. "Eighty five per cent of the smokers that are addicted to smoking tobacco, they start in their teen years. Rarely do you see people start smoking at 30 years old."