A new study reinforces the damaging effects of smoking during pregnancy which leads to abnormal rates of blood pressure and heart rate control in newborn babies that continue to deteriorate throughout the first year of life.

Lead author of the study, Gary Cohen, a senior research scientist in the department of women and child health at the Karolinska Institute in Stockholm stated, “Babies of smokers have evidence of persistent problems in blood pressure regulation that start at birth and get worse over time.

“This study reveals for the first time that early life exposure to tobacco can lead to long-lasting reprogramming of infant blood pressure control mechanisms.”

Details of the study
The Swedish researchers compared 19 infants of non-smoking couples with 17 babies of women who smoked an average of 15 cigarettes daily during and after pregnancy.

All the babies had normal weight at birth and were breast fed. For the study, the blood pressure and heart rates of all the infants were recorded while they slept at a tilting position of 60 degree angle during the first week, then at three months and later at one year.

Observations by researchers
The investigators found that a week after birth, the babies of non-smoking mothers showed a two percent increase in blood pressure when tilted upright which increased to 10 percent within a year.

On the other hand, the infants exposed to the tobacco fumes during pregnancy exhibited a reverse trend.

They experienced a 10 percent increase in blood pressure during a tilt at one week which increased to four percent at 12 months of age.

Additionally, the heart rate response in babies born to smoking mothers was ‘abnormal and highly exaggerated’.

Explaining the mechanism the lead researcher, Miriam Katz-Salamon stated, "Normally when a person stands, the heart rate increases and the blood vessels constrict to keep blood flow to the heart and brain.

“Our findings show that infants of smokers have a hyper-reactive system in the first weeks of life because the blood pressure increases too much when they are tilted up, but at one year they under-react and are less effective in adapting to an upright position.”

Implications of the study
The researchers admit that it is difficult to decipher why exposure to tobacco fumes during pregnancy is hazardous to the infant, but one explanation could be that smoking might be damaging the “structure and function of the blood vessels.”

Cohen added, "What we know from studies in older kids is that even if you remove them from an environment of exposure to tobacco smoke, it is unlikely you will get full restoration of normal function.

"The best intervention to solve these problems is prevention. Women who are pregnant need to avoid exposure to tobacco smoke in the air. Passive smoke exposure can be as bad as being an active smoker."

Details of the study are published in the scientific journal, Hypertension.