Fertility and pregnancy * Babies and children

Smokers' babies can have abnormal blood pressure

newborn baby Condition persists in first year

Babies born to mothers who smoked during pregnancy have been found to have abnormal blood pressure control which persists throughout the first year of life, according to a new study.

Scientists from the Karolinska Institute in Sweden measured the blood pressure and heart rates in 36 babies during their first weeks, at three months, and when one year old. All were of normal weight at birth and were breast fed.

Seventeen of the babies were born to mothers who smoked at least 15 cigarettes a day.

Blood pressure and heart rates were measured while the babies were asleep and tilted up at a 60 degree angle, before being laid down again.

Normally, when someone stands, the heart rate increases and blood vessels tighten to keep blood flow to the heart and brain. This causes an increase in blood pressure which then returns to normal when lying down.

However, this blood pressure response to tilting the babies upright during sleep was found to be "dramatically different" in babies born to smoking mothers compared to those born to non-smoking parents.

At a few weeks old, the babies born to non-smokers had a 2% increase in blood pressure when tilted upright at one week of age compared with a 10% increase in babies born to smokers.

When a year old, the findings were reversed. Babies born to non-smokers had a 10% increase in blood pressure when tilted compared with a 4% increase in the babies born to smokers.

At aged three months and one year, the heart rate response to tilting in the babies born to smokers was found to be "abnormal and highly exaggerated", the researchers reported.

“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,” said Dr Gary Cohen, the senior research scientist who led the study.

The researchers plan to track the infants further to find out whether the problems continue when they become older.

“The seeds of many diseases probably are sown very early in life,” Dr. Cohen said.

“Babies of smokers may already be showing signs that they are more likely to develop high blood pressure later in life.”

The study is published in the January 25 online version of the Journal Hypertension.

This article was published on Tue 26 January 2010



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