Smoking during pregnancy can chemically modify the DNA of unborn babies. Researchers found spots in the blood samples of babies born to mothers who smoked. The finding can expand the understanding between childhood health problems and the mother-to-be's smoking during pregnancy.

In the study, researchers gathered blood samples from the umbilical cords of newborn babies. They discovered that the DNA of babies born to mothers who regularly smoked was chemically altered and had more than 6,000 spots.

Half of these spots were associated with specific genes such as smoking-related cancers, asthma, birth defects (cleft palates and cleft lips) and those genes involved in the development of the lungs and the nervous system.

These epigenetic changes don't necessarily alter the DNA sequence. However, they do if specific genes are turned "on" or "off." Alarmingly, many of these fetal DNA changes persisted after birth. They also found them in older children, with an average age of 7, who were born to mothers who regularly smoked during their pregnancies.

"This is a blood-borne exposure to smoking – the fetus isn't breathing it, but many of the same things are going to be passing through the placenta," said epidemiologist Stephanie London, who is one of the study's senior authors. London is also a U.S. National Institute of Environmental Health Sciences physician.

Apart from the epigenetic changes in the newborn babies, the team found that these changes are similar to the alteration found in adult smokers in past studies. The research was published in the American Journal of Human Genetics on March 31.

E-cigarettes Are Not Safe Either

In a recent mice study, researchers found that newborns exposed to the e-cigarette vapor right after birth or those born to mothers who were exposed to the vapor during their pregnancy appeared hyperactive compared to the ones who were not.

This mice study followed through a previous one wherein researchers found that a "relatively low" exposure to the chemicals in e-cigarettes can affect the gene activity in the fetal brain's developing frontal cortex. The analysis of the gene activity suggested it could result in decreased memory, coordination and learning as well as the development of attention deficit hyperactivity disorder (ADHD).

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