Nav: Home

Mom's smoking alters fetal DNA

March 31, 2016

A study of over 6,000 mothers and their newborn children--one of the largest studies of its kind--solidifies the evidence that smoking cigarettes while pregnant chemically modifies a fetus' DNA, mirroring patterns seen in adult smokers. The researchers also identify new development-related genes affected by smoking. The work, published March 31 in the American Journal of Human Genetics, suggests a potential explanation for the link between smoking during pregnancy and health complications in children.

"I find it kind of amazing when we see these epigenetic signals in newborns, from in utero exposure, lighting up the same genes as an adult's own cigarette smoking. There's a lot of overlap," says co-senior author Stephanie London, an epidemiologist and physician at the National Institute of Environmental Health Sciences (NIEHS), part of the National Institutes of Health. "This is a blood-borne exposure to smoking--the fetus isn't breathing it, but many of the same things are going to be passing through the placenta."

Links between smoking and chemical modifications to DNA, or methylation, have been found for developing fetuses in smaller studies, but the larger analysis gives scientists more power to uncover patterns. An international team of researchers pooled results from 6,685 newborns and their mothers around the world. Based on questionnaires, mothers were labeled as "sustained smokers" who smoked cigarettes daily throughout most of pregnancy (13 percent), "non-smokers" (62 percent), or those with "any smoking" during pregnancy (25 percent), which captured mothers who were occasional smokers or who quit smoking early on.

To analyze methylation in the newborns' DNA, researchers collected samples mainly from blood in the umbilical cord after delivery. For the newborns whose mothers fell into the "sustained smoker" category, the research teams identified 6,073 places where the DNA was chemically modified differently than in the "no smoking" newborns. About half of these locations could be tied to a specific gene.

London and her colleagues found that this collection of genes related to lung and nervous system development, smoking-related cancers, birth defects such as cleft lip and palate, and more. "Many signals tied into developmental pathways," says Bonnie Joubert, an epidemiologist at the NIEHS and a co-first author on the paper. In a separate analysis, many of these DNA modifications were still apparent in older children whose mothers had smoked during pregnancy.

Next steps include building on the preliminary gene-expression analyses conducted by the research team to better understand how these DNA modifications might influence child development and disease. For example, London says, "We already knew that smoking is related to cleft lip and palate, but we don't know why. Methylation might be somehow involved in the process."

This is the first paper from the international Pregnancy and Childhood Epigenetics (PACE) consortium. PACE is applying the "consortium approach" to additional studies, bringing large teams of scientists together on questions such as the impact of a mother's body weight, alcohol intake, and air pollution on her child's epigenetic marks--and the effects of those marks on the child's health. "It's important to recognize the many people involved and the work that they did," says Joubert.
-end-
American Journal of Human Genetics, Joubert et al.: "DNA Methylation in Newborns and Maternal Smoking in Pregnancy: Genome-wide Consortium Meta-analysis" http://dx.doi.org/10.1016/j.ajhg.2016.02.019

The American Journal of Human Genetics, published by Cell Press for the American Society of Human Genetics, is a monthly journal that provides a record of research and review relating to heredity in humans and to the application of genetic principles in medicine and public policy, as well as in related areas of molecular and cell biology. For more information, please visit http://www.cell.com/ajhg . To receive Cell Press media alerts, contact press@cell.com

Cell Press

Related Smoking Articles:

A case where smoking helped
A mutation in the hemoglobin of a young woman in Germany was found to cause her mild anemia.
No safe level of smoking
People who consistently smoked an average of less than one cigarette per day over their lifetime had a 64 percent higher risk of earlier death than people who never smoked.
Nearly half of women who stop smoking during pregnancy go back to smoking soon after baby is born
A major new review published today by the scientific journal Addiction reveals that in studies testing the effectiveness of stop-smoking support for pregnant women, nearly half (43 percent) of the women who managed to stay off cigarettes during the pregnancy went back to smoking within six months of the birth.
If you want to quit smoking, do it now
Smokers who try to cut down the amount they smoke before stopping are less likely to quit than those who choose to quit all in one go, Oxford University researchers have found.
Cochrane news: Have national smoking bans worked in reducing harms in passive smoking?
The most robust evidence yet, published today in the Cochrane Library, suggests that national smoking legislation does reduce the harms of passive smoking, and particularly risks from heart disease.
Advocating for raising the smoking age to 21
Henry Ford Hospital pulmonologist Daniel Ouellette, M.D., who during his 31-year career in medicine has seen the harmful effects of smoking on his patients, advocates for raising the smoking age to 21.
Stress main cause of smoking after childbirth
Mothers who quit smoking in pregnancy are more likely to light up again after their baby is born if they feel stressed.
As smoking declines, more are likely to quit
Smokeless tobacco and, more recently, e-cigarettes have been promoted as a harm reduction strategy for smokers who are 'unable or unwilling to quit.' The strategy, embraced by both industry and some public health advocates, is based on the assumption that as smoking declines overall, only those who cannot quit will remain.
Smoking around your toddler could be just as bad as smoking while pregnant
Children whose parents smoked when they were toddlers are likely to have a wider waist and a higher BMI by time they reach ten years of age, reveal researchers at the University of Montreal and its affiliated CHU Sainte Justine Research Centre.
Smoking and angioplasty: Not a good combination
Quitting smoking when you have angioplasty is associated with better quality of life and less chest pain.

Related Smoking Reading:

Best Science Podcasts 2019

We have hand picked the best science podcasts for 2019. Sit back and enjoy new science podcasts updated daily from your favorite science news services and scientists.
Now Playing: TED Radio Hour

Jumpstarting Creativity
Our greatest breakthroughs and triumphs have one thing in common: creativity. But how do you ignite it? And how do you rekindle it? This hour, TED speakers explore ideas on jumpstarting creativity. Guests include economist Tim Harford, producer Helen Marriage, artificial intelligence researcher Steve Engels, and behavioral scientist Marily Oppezzo.
Now Playing: Science for the People

#524 The Human Network
What does a network of humans look like and how does it work? How does information spread? How do decisions and opinions spread? What gets distorted as it moves through the network and why? This week we dig into the ins and outs of human networks with Matthew Jackson, Professor of Economics at Stanford University and author of the book "The Human Network: How Your Social Position Determines Your Power, Beliefs, and Behaviours".