No level of smoke exposure is safe while pregnant, can cause genetic changes in the baby

RICHMOND, Va. — Even minimal exposure to second-hand smoke can potentially impact a pregnant woman’s unborn child, according to troubling new findings from researchers at Virginia Commonwealth University. Study authors report smoke can spark epigenetic changes, meaning there could be fluctuations in the regulation of gene expression within the baby. Making matters worse, close to a quarter of pregnant women say they’ve been exposed to secondhand smoke at some point while expecting.

Researchers note these changes in the DNA may put a child at greater risk of developing developmental disorders or cancer later on.

“What we recommend to mothers in general is that no level of smoke exposure is safe,” says study lead author Bernard Fuemmeler, Ph.D., M.P.H., associate director for population science and interim co-leader of the Cancer Prevention and Control program at VCU Massey Cancer Center, in a university release. “Even low levels of smoke from secondhand exposure affect epigenetic marks in disease-related pathways. That doesn’t mean everyone who is exposed will have a child with some disease outcome, but it contributes to a heightened risk.”

This is the first study to find a connection between maternal secondhand smoke exposure while pregnant and subsequent epigenetic changes to disease-related genes, which doctors measure at birth. In a broader sense, these findings support the theory that many human diseases take root in a person very early in life due to environmental factors. Such influential elements can include stress, diet, air pollution, and smoke exposure.

Nicotine can pass from mother to child during pregnancy

The team analyzed data from 79 pregnant women enrolled in the Newborn Epigenetics Study (NEST) between 2005 and 2011. All of those women had cotinine, a nicotine by-product, in their blood during their first trimesters. The cotinine levels measured varied; some suggested more exposure than others while a few indicated little to no exposure at all.

After giving birth, researchers took blood samples from each woman’s umbilical cord – the same blood that circulates through the fetus in utero. The team then conducted an epigenome-wide association study (EWAS) on the blood samples to look for ties between the mother’s blood cotinine levels during pregnancy and genetic patterns in the babies after birth.

Results show babies born to mothers with higher cotinine levels were more likely to show epigenetic “marks” on genes controlling brain functioning, diabetes, and cancer development.

To solidify these findings, study authors repeated the same analysis with another 115 pregnant women. Once again, they detected changes to two of the same disease-related epigenetic regions which match with cotinine levels in the mothers. The first of those regions has a connection with inflammation and diabetes, while the second helps regulate cardiovascular and nervous system functions.

“It highlights the importance of clean air,” Fuemmeler concludes. “It’s important not only for our homes, but also in the environment. Clean air policies limit smoke in public, and for pregnant women that may have long-term effects on offspring.”

The study appears in the journal Environmental Health Perspectives.

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