Researchers at John Hopkins University Bloomberg School of Public Health led a study where the blood of 531 children up to five years old were tested to see if they could find any evidence that shows that their mother's smoked during pregnancy. In a previous study, there were presences of epigenetic marks, which include DNA methylation, in the DNA of a newborn's umbilical cord at 26 locations of the genome. The epigenetic markers are molecules not part of the DNA sequence and regulate the turning on and off of genes.
This new study took this even further, by finding that when the 26 epigenetic markers were looked at in the children, 81% of the time the researchers could correctly predict that there was prenatal smoking. Although, in some cases it could be from exposure to secondhand smoke after birth. This study overall found that not only is the DNA marked in newborns, but it is still shows the epigenetic markers even five years after the children are born. This is known as an epigenetic memory. Prenatal smoking causes many health problems for children down the line and finding out if their mother's smoked during pregnancy can at least get a head start in preventing or treating these problems. I never knew that you can actually tell if a woman smoked during pregnancy, especially in the DNA of their child even after five years of being born.