How smoking during pregnancy affects you and your baby

Ob gyn Robert Welch has helped thousands of women with high risk pregnancies realize their dreams of a healthy baby. But even after all those successes, there’s still one situation that truly scares him a pregnant woman who can’t quit smoking.

“Smoking cigarettes is probably the No. 1 cause of adverse outcomes for babies,” says Welch, who’s the chairman of the Department of Obstetrics and Gynecology at Providence Hospital in Southfield, Michigan. He’s seen the complications far too many times babies born prematurely, babies born too small, babies who die before they can be born at all. In his view, pregnancies would be safer and babies would be healthier if pregnant smokers could somehow swap their habit for a serious disease such as diabetes or high blood pressure.

“I can control those conditions with medications,” Welch says. But when a pregnant woman smokes, he says, nothing can protect her baby from danger.

Why is it so dangerous to smoke during pregnancy?

Cigarette smoke contains more than 4,000 chemicals, including truly nasty things like cyanide, lead, and at least 60 cancer causing compounds. When you smoke during pregnancy, that toxic brew gets into your bloodstream, your baby’s only source of oxygen and nutrients.

While none of those 4,000 plus chemicals is good for your baby (you would never add a dollop of lead and cyanide to his strained peaches), two compounds are especially harmful nicotine and carbon monoxide. These two toxins account for almost every smoking related complication in pregnancy, says ob gyn James Christmas, director of Maternal Fetal Medicine for Commonwealth Perinatal Associates at Henrico Doctors’ Hospital in Richmond, Virginia.

The most serious complications including stillbirth, premature delivery, and low birth weight can be chalked up to the fact that nicotine and carbon monoxide work together to reduce your baby’s supply of oxygen. Nicotine chokes off oxygen by narrowing blood vessels throughout your body, including the ones in the umbilical cord. It’s a little like forcing your baby to breathe through a narrow straw. To make matters worse, the red blood cells that carry oxygen start to pick up molecules of carbon monoxide instead. Suddenly, that narrow straw doesn’t even hold as much oxygen as it should.

How will smoking affect my baby?

A shortage of oxygen can have devastating effects on your baby’s growth and development. On average, smoking during pregnancy doubles the chances that a baby will be born too early or weigh less than 5 1/2 pounds at birth. Smoking also more than doubles the risk of stillbirth.

Every cigarette you smoke increases the risks to your pregnancy. A few cigarettes a day are safer than a whole pack, but the difference isn’t as great as you might think. A smoker’s body is especially sensitive to the first doses of nicotine each day, and even just one or two cigarettes will significantly tighten blood vessels. That’s why even a “light” habit can have an outsize effect on your baby’s health.

How smoking affects your baby

Weight and size
On average, a pack a day habit during pregnancy will shave about a half pound from a baby’s birth weight. Smoking two packs a day throughout your pregnancy could make your baby a full pound or more lighter. While some women may welcome the prospect of delivering a smaller baby, stunting a baby’s growth in the womb can have negative consequences that last a lifetime.

Body and lungs
Undersize babies tend to have underdeveloped bodies. Their lungs may not be ready to work on their own, which means they may spend their first days or weeks attached to a respirator. After they’re breathing on their own (or even if they did from the start), these babies may have continuing breathing problems because of delayed lung development or other adverse effects of nicotine. Children whose mothers smoked during pregnancy are especially vulnerable to asthma, and have double or even triple the risk of sudden infant death syndrome (SIDS).


Babies whose mother smoked in the first trimester of pregnancy are more likely to have a heart defect at birth.

In a U.S. Centers for Disease Control and Prevention (CDC) study published in February 2011, these babies’ risk of having certain types of congenital heart defects was 20 to 70 percent higher than it was for babies whose moms didn’t smoke. The defects included those that obstruct the flow of blood from the right side of the heart into the lungs (right ventricular outflow tract obstructions) and openings between the upper chambers of the heart (atrial septal defects).

Researchers analyzed data on 2,525 babies who had heart defects at birth and 3,435 healthy babies born in Baltimore and Washington, D.C., between 1981 and 1989.

Brain function
Smoking during pregnancy can have lifelong effects on your baby’s brain. Children of pregnant smokers are especially likely to have learning disorders, behavioral problems, and relatively low IQs.

Are any types of cigarettes safe to smoke?

No. All cigarettes cause damage, and any tobacco smoking is dangerous. All tobacco is addictive.

Some people try to make their smoking habit safer by smoking fewer cigarettes, which most smokers find quite hard to do. Sadly, research has found that even smoking as few as 1 to 4 cigarettes a day can lead to serious health outcomes, including an increased risk of heart disease and a greater chance of dying at a younger age.

Smokers once believed that “light” cigarettes meant lower health risk. This is not true. Studies found that the risk of serious health effects is not lower in smokers of light or low tar cigarettes. Because of this, the US Food and Drug Administration (FDA) has banned use of the terms “light,” “mild,” and “low” in any cigarette sales unless the FDA specifically allows it and so far, they haven’t. But this rule doesn’t apply to the small cigarette like cigars (see our document Cigar Smoking).

Some people think hand rolled cigarettes are a cheaper and healthier way to smoke, but they are no safer than commercial brands. In fact, life long smokers of hand rolled cigarettes have been found to have a higher risk of cancers of the larynx (voice box), esophagus (swallowing tube), mouth, and pharynx (throat) when compared with smokers of machine made cigarettes.

Some cigarettes are now being sold as “all natural.” They are marketed as having no chemicals or additives and rolled with 100% cotton filters. There’s no proof they are healthier or safer than other cigarettes, nor is there good reason to think they would be. All smoke from cigarettes, natural or otherwise, contains many agents that cause cancer (carcinogens) and toxins that come from burning the tobacco itself, including tar and carbon monoxide.

Even herbal cigarettes that do not contain tobacco give off tar, particulates, and carbon monoxide and are dangerous to your health.

What about menthol cigarettes aren’t they safer?

Menthol cigarettes are not safer than unflavored cigarettes. In fact, they might even be more dangerous. These cigarettes tend to be “easier” to smoke the added menthol produces a cooling sensation in the throat when the smoke is inhaled. It lessens the cough reflex and covers the dry feeling in the throat that smokers often have. People who smoke menthol cigarettes can inhale deeper and hold the smoke in longer.

Nearly one third (32%) of all cigarettes sold in the United States are flavored with menthol. These cigarettes are most popular among children, teens, African Americans, Hispanics, and smokers in other minority groups.

Studies have shown that people who smoke menthol cigarettes are less likely to try to quit and are less likely to succeed when they do try. At least one researcher proposed that menthol smokers might want to switch to non menthol cigarettes before they quit to improve their chances of quitting smoking.

Most people don’t know that many cigarette brands that are not advertised as having menthol often have a small amount of menthol added. Even amounts of menthol that are too small to taste can make a cigarette seem smoother and less harsh. These small amounts of menthol can ease the path for new smokers.

No matter what they smell like, taste like, look like, or are labeled as, all cigarettes are bad for you. The bottom line is there’s no such thing as a safe smoke.

Are e cigarettes safe?

Electronic cigarettes or e cigarettes are designed to look like cigarettes. When the smoker puffs on it, the system delivers a mist of liquid, flavorings, and nicotine that looks something like smoke. The smoker inhales it, and the nicotine is absorbed into the lungs. Some people think they can be used to help people give up tobacco.

The makers of e cigarettes say that they are safe, but this only means the ingredients have been found to be safe to eat. Inhaling a substance is not the same as swallowing it. There are questions about how safe it is to inhale some substances in the e cigarette vapor into the lungs. Since e cigarettes are not labeled with their ingredients, the user doesn’t know what’s in them. The amounts of nicotine and other substances a person gets from each cartridge are also unclear.

A study done by the FDA found cancer causing substances in half the e cigarette samples tested. Other impurities were also found, including one sample with diethylene glycol, a toxic ingredient found in antifreeze.

Studies have shown that e cigarettes can cause short term lung changes that are much like those caused by regular cigarettes. But long term health effects are still unclear. This is an active area of research.

We do know that electronic cigarettes are designed to deliver nicotine, and nicotine is addictive. This strongly suggests that e cigarette use will lead to dependence, unless the user weans him or herself from them. A CDC survey published in 2013 showed that e cigarette use in middle school and high school students doubled between 2011 and 2012, with 10% of high school students and 3% of middle school kids using them and risking addiction to nicotine. Among high school students, 80% smoked regular cigarettes and used e cigarettes at the same time.

Because the American Cancer Society doesn’t yet know whether e cigarettes are safe and effective, we cannot recommend them to help people quit smoking. There are proven methods available to help people quit, including pure forms of inhalable nicotine as well as nasal sprays, gums, and patches.

Until electronic cigarettes are scientifically proven to be safe and effective, ACS will support the regulation of e cigarettes and laws that treat them like all other tobacco products.

A word about nicotine

Although other substances in cigarettes are known to cause cancer, nicotine is the addictive substance in tobacco. Nicotine is an addictive drug just like heroin and cocaine, and it keeps people coming back for more. Anyone who starts smoking or using tobacco in other forms can become addicted to nicotine.