Smoking during pregnancy could be fatal for unborn

May 31st, 2008 - 5:48 pm ICT by admin  


Washington, May 31 (IANS) Smoking could be fatal for the unborn child, said a new study that links it with the Sudden Infant Death Syndrome. “Our results provide some of the most direct evidence suggesting that prenatal cigarette smoke exposure can contribute to destabilizing effects of hypoxia (low oxygen) and thermal stress on neonatal breathing,” informed Shabih Hasan of University of Calgary and principal investigator of the study.

Other contributing factors include disturbance in breathing and heart rate regulation, impaired arousal responses, thermal stress (primarily overheating from too high temperatures or too much clothing) and sleeping in the prone (belly-down) position.

To investigate the compounding effects of smoking on other known risk factors for Sudden Infant Death Syndrome (SIDS), namely thermal and oxygen stress, researchers exposed pregnant rat pups to either room air (control) or mainstream cigarette smoke equivalent to that a pack-a-day smoker would experience.

“Our approach sought to quantify the effects of cigarette smoke holistically, rather than using nicotine exposure as a proxy for cigarette smoke.

“Nicotine is just one of the 4,700 known toxins in cigarette smoke that could have protracted effects on embryonic development and postnatal growth,” said Hasan.

In this study, both plasma nicotine levels in the mothers and reduced birth weight in the pups were comparable to those of moderate to heavy smoking human mothers and the infants born to them.

A total of 30 control and 39 cigarette smoke-exposed one-week-old rat pups were randomised to undergo exposure to an oxygen-depleted environment. Researchers then analysed respiratory responses to the challenges.

Overall, just 13 percent of the control animals exhibited gasping, whereas nearly three times that - 36 percent - of the cigarette smoke exposed animals did.

But the effects were much more pronounced in pups that head been exposed to cigarette smoked prenatally.

“Our results show that exposure compounds the risk by increasing the likelihood of gasp-like respiration and prolonging the time that it takes for neonates to return to normal breathing following hypoxia,” said Hasan.

The new study appears in the first issue for June of the American Journal of Respiratory and Critical Care Medicine.

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