US-based scientists say their research may allow for more normal development of babies born to the thousands of mothers who cannot give up the habit during pregnancy.
While the new study, published in the 1 May edition of the American Journal of Respiratory and Critical Care Medicine (vol 171, issue 9, pp1032-9), was carried out on monkeys, Eliot Spindel, senior author of the paper based at the Oregon Health & Science University said the findings are "highly applicable to humans".
"The sad reality is that approximately 11 per cent of pregnant mothers continue to smoke during pregnancy - this translates to about a half a million American women a year," he said.
Smoking during pregnancy can cause premature delivery, growth retardation and has been blamed for 5-10 per cent of all foetal and neonatal deaths.
Maternal smoking can also cause decreased lung function and increased respiratory illness in offspring. It is thought that the nicotine in cigarettes is a key cause of these problems, crossing the placenta to interact with cells in the unborn infant's developing lungs.
The Oregon team studied a small group of infant monkeys born to mothers who received regular doses of nicotine comparable to those of a smoking human mother. The breathing abilities and lung development of these monkeys was then compared with monkeys born to mothers who had received both nicotine and 250 mg vitamin C per day during pregnancy.
A third group of baby monkeys that did not receive either nicotine or vitamin C during prenatal development were studied as a control group.
"We found that animals exposed to nicotine prior to birth had reduced air flow in the lungs compared to animals that were given nicotine and vitamin C. In fact, the nicotine plus vitamin C group had lung air flow close to that of a normal animal," explained Spindel.
"Other notable observations were that increased levels of surfactant apoprotein B protein normally caused by nicotine were reduced by vitamin C," he said.
In addition, elastin levels in the lungs appeared to be slightly impacted by vitamin C. This finding may be significant as elastin plays a key role in the expansion and contraction of the lung during breathing, added Spindel.
However the scientists note that vitamin C did not counteract other negative health impacts of smoking during pregnancy such as abnormal brain development and decreased body weight. The scientists also caution that more research is needed in regard to determining the appropriate vitamin C dosage for humans.
Finally, studies need to be conducted to demonstrate that giving pregnant women higher levels of vitamin C will not itself cause development problems.