Pregnant women hear a lot about things they should avoid: alcohol, tobacco, chemical exposures, stress. All of those have the potential to affect a developing fetus. And now scientists are beginning to understand why.
One important factor, they say, is something called epigenetics, which involves the mechanisms that turn individual genes on and off in a cell.
There’s growing evidence that epigenetics is critical in determining a child’s risk of developing problems ranging from autism to diabetes, says Dani Fallin, who studies the genetics of mental disorders at Johns Hopkins Bloomberg School of Public Health.
Epigenetic control of genes is part of what allows a tiny cluster of identical cells in the womb to grow into a fully formed baby. By switching certain genes on and off, some cells become heart cells while others become brain cells.
It’s a delicate process that can be disrupted by exposure to certain chemicals or hormones, says Susan Kay Murphy, an associate professor of obstetrics and gynecology at Duke University School of Medicine. And the first week or so after conception appears to be “a particularly vulnerable time where environmental influences can directly affect an epigenetic outcome,” she says.
Murphy’s interest in epigenetics is personal as well as professional. She entered the field in the 1990s after her young son died from a rare form of liver cancer that has been linked to epigenetic changes. She also has a son with autism and a daughter with ADHD.
Illustration by Katherine Streeter for NPR