From Scientific American:
Since the birth of the first “test tube baby” in 1978, more than three million children have been born with the help of reproductive technology. Most of them are healthy. But as a group they're at a higher risk for low birth weight, which is associated with obesity, hypertension and type 2 diabetes later in life.
Carmen Sapienza, a geneticist at Temple University School of Medicine in Philadelphia, is studying two groups of children—one comprising those conceived naturally, the other made up of children conceived via assisted reproductive technology—to identify epigenetic (changes in gene expression caused by molecular mechanisms other than mutations in the DNA sequence itself) differences among them. He is particularly interested in a chromosomal modification called “DNA methylation,” research he presented February 22 at the annual meeting of the American Association for the Advancement of Science. “We found that 5 to 10 percent of these chromosome modifications were different in children born through assisted reproduction, and this altered the expression of nearby genes,” Sapienza says. Several of the genes whose expression differed between the two groups have been implicated in chronic metabolic disorders, such as obesity and type 2 diabetes.