Prenatal smoking shows up in little kids’ blood

This was the finding of a study led by Johns Hopkins Bloomberg School of Public Health in Baltimore, MD, and published in the journal Environmental Research. Previous research has already established that the DNA of cord blood from newborns is altered if the mother smokes during pregnancy. The difference is not in the genetic code itself but in the presence of “epigenetic” marks left on the DNA at 26 locations of the genome. Epigenetic markers are molecules that attach to genes and influence their activity, such as switching them on or off.

Researchers tested the blood of 531 preschoolers from six different places in the US and interviewed their mothers to find out if they had smoked when they were pregnant with those children. They looked at the 26 epigenetic markers in the children’s blood samples and found 81% of the time they could use them to predict whether the mother had smoked during pregnancy. The study is the first to show that an epigenetic memory, or signature, of the mother’s smoking during pregnancy can remain in the child’s blood as long as 5 years after birth. The researchers acknowledge it is possible that in some cases the epigenetic memory could be related to secondhand smoke exposure after birth, but this would not account for all of it, bearing in mind the previous finding that the signature can already be present in cord blood.

They suggest the findings point to possibilities beyond smoking. It is relatively easy to establish, by asking the mother, if a child has been exposed to tobacco smoking before birth. It is not so easy to establish if they have been exposed to other toxins the mother may not know. Lead author Christine Ladd-Acosta, assistant professor of epidemiology at the Bloomberg School, concludes, “If epigenetic signatures can be found for other environmental exposures, these could provide clues to how certain prenatal exposures affect health and potentially decades into life.”

Researchers in Japan urge greater awareness after finding that children who are exposed to secondhand smoke as they grow have double the risk of tooth decay. The findings offer strong evidence that environmental exposures go as far back as the womb remain in the body and may affect a person’s health for years after birth.

 

For more information please visit: www.jhsph.edu

 

fetus