Study Finds That No Amount Of Secondhand Smoke Exposure Is Safe For Pregnant People

by Colleen Dilthey Thomas
Originally Published: 
Scary Mommy and Burak Karademir/Getty

By now, there is no question that smoking is dangerous. It is a foolish and selfish way to harm yourself and others. According to the CDC, cigarette smoking is responsible for more than 480,000 deaths in the United States each year. Among them, 41,000 deaths are from secondhand smoke. That averages to one in five deaths annually, or approximately 1,300 deaths per day. It is mind boggling that with these facts so well known that people continue to smoke. But even more infuriating is that smokers expose our pregnant women and children to their nasty habit.

Many states have come up with indoor clean air acts to help prevent secondhand smoke exposure. Major cities like New York and Los Angeles have banned smoking in indoor spaces. These policies have been enacted not only to prevent, but hopefully encourage those to quit smoking in public but to also protect others from second hand smoke.

The American Pregnancy Association explains that, “Secondhand smoke is characterized as the product released into the environment whenever someone who is smoking exhales. It can also come from the end of tobacco-containing smoking products. There are approximately 4,000 chemicals present in second-hand smoke, many of which have been determined to be related to cancer. If you are exposed to secondhand smoke during pregnancy, both you and your baby are put at risk.”

A recent study by Virginia Commonwealth University reports that no exposure to secondhand smoke during pregnancy is safe and that pregnant women need to avoid secondhand smoke completely. Researchers found that for the first time, there was a concrete correlation between second-hand smoke and disease-related gene regulation in babies. This means that during early development, exposure to stress, poor nutrition, pollution, and cigarette smoke can be the cause of many adult diseases.

Dr. 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, and colleagues collected and analyzed data from 79 pregnant women who enrolled in the Newborn Epigenetics Study between 2005 and 2011. The women had a nicotine byproduct, cotinine, in their systems during the first trimester. This byproduct was consistent with smoke exposure to those who were around secondhand smoke.

Passive smoking in pregnancy. Selfish man is smoking cigarette. Pregnant woman in background.

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After these women gave birth, the researchers sampled the umbilical cord blood, which is the same blood that circulates through the fetus in utero, and performed what’s referred to as an epigenome-wide association study (EWAS) to search for correlations between blood cotinine levels of the mothers during pregnancy and epigenetic patterns in the babies at birth.

The research found that the babies with higher cotinine levels were more likely to have epigenetic marks on their genes. These marks appeared on genes that control the development of the brain and those related to both cancer and diabetes.

To solidify their results, the team repeated the analysis in a separate sample of 115 women and found changes to disease-related epigenetic regions that regulate inflammation and diabetes, and one that regulates both cardiovascular and nervous system functions. There was a direct correlation between mothers and their cotinine levels.

“It highlights the importance of clean air,” Fuemmeler, who is also a professor of health behavior and policy in the VCU School of Medicine and holds the Gordon D. Ginder, M.D., Chair in Cancer Research at Massey, said in a statement. “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 noted that in all of the analyses race, ethnicity, age, prior number of children and maternal education were all controlled.

Dr. Heather Lopez, an obstetrics and gynecology specialist with BJC Medical Group Women’s Health Care at Missouri Baptist Hospital, told Scary Mommy that in addition to genetic issues, babies exposed to secondhand smoke during pregnancy face other obstacles. “After delivery, babies in contact with secondhand smoke can be at risk for sudden infant death syndrome (SIDS) which is a disorder where an infant dies unexpectedly while they are sleeping. They are also more likely to have recurrent ear infections, respiratory viruses, and are at higher risk for developing asthma.”

In addition, she warned that women exposed to second-hand smoke during pregnancy are at a higher risk for miscarriage, low birth weight and preterm birth. She encouraged women who are pregnant to avoid public places where there could be smoking. She added that it is important to ask visitors and family to always smoke outside and most importantly, encourage those around you to quit smoking.

“Be an advocate for yourself and your baby!” she advised. “Do not be afraid to ask people to not smoke around you and your baby.” As a parent, you’ll be advocating for them all their life anyway — may as well start early.

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