Smoking during pregnancy: effects, risks and quitting smoking

It’s common knowledge that smoking should be avoided during pregnancy. Cigarette smoke not only puts the mother’s health at risk, but also the baby’s. Children of women who smoke are often born underweight and with birth defects, yet many expectant mothers continue to smoke. What exactly happens in your baby’s body when you smoke? Which effects are actually proven, and what is just a myth? And could suddenly quitting smoking even be more harmful to the baby than continuing to smoke?

In this article, you’ll find the answers to these and other questions about smoking during pregnancy.

How smoking during pregnancy harms the unborn baby — the mechanism

What exactly makes cigarette smoke so harmful to babies in the womb? Smoking during pregnancy harms the unborn baby because toxins such as nicotine and carbon monoxide pass unfiltered through the placenta into the baby’s bloodstream, where they impair the vital supply of oxygen and nutrients. Tobacco smoke contains more than 7,000 chemical compounds, including toxic substances such as tar, carbon monoxide, and heavy metals¹, all of which harm the unborn child with every single cigarette. There is no safe minimum amount of tobacco smoke.

Nicotine constricts, carbon monoxide displaces

Two ingredients in cigarette smoke that are particularly dangerous for the fetus are nicotine and carbon monoxide (CO). Nicotine has a vasoconstrictive effect: it causes blood vessels, including those in the placenta, to narrow. Reduced blood flow means less oxygen reaches the unborn baby. Because nicotine has a high addiction potential and directly affects the baby’s brain, children of smokers are more likely to become addicted to cigarettes themselves later in life.

At the same time, CO from cigarette smoke accumulates in the fetal bloodstream and binds to the red blood pigment hemoglobin, which normally transports oxygen to the organs. CO and hemoglobin form carboxyhemoglobin, blocking oxygen transport. Fetal hemoglobin has a particularly strong affinity for carbon monoxide, which is broken down in the unborn baby’s body four to five times more slowly than in adults². This can lead to fetal hypoxemia, a prolonged undersupply. The fetus is also not yet able to break down many of the toxic substances in smoke on its own because its detoxification system is not yet fully developed.

Don’t forget: when you smoke, your unborn baby smokes too. In medicine, this is referred to as so-called fetal tobacco syndrome. This term covers all health damage that can result from prenatal tobacco exposure (in other words, the unborn baby’s exposure to harmful substances through tobacco use).

more about the effects of nicotine

Folic acid: the underestimated side effect

A link that is rarely mentioned: nicotine and other toxins in tobacco smoke disrupt metabolism and increase the body’s use and breakdown of folic acid (vitamin B9), which is why pregnant smokers often have lower folic acid levels and folic acid deficiency. However, folic acid is a particularly important vitamin in the first weeks of pregnancy for the development of your child’s spinal cord and spine. A folic acid deficiency in early pregnancy is the most common cause of a neural tube defect in the child, commonly referred to as an “open spine.” In this case, the vertebral arches and the neural tube do not close completely in the first weeks of pregnancy, and parts of the spinal cord or its membranes bulge outward. If this malformation is located in the upper back area, paralysis and sensory disorders can result, and affected children may be confined to a wheelchair for life⁵.

Secondhand smoke is not a way out

But if you do not smoke yourself and only inhale the smoke passively, it is less harmful, right? In fact, when smoking, only a quarter of the cigarette smoke is inhaled by the smoker, while the rest (the smoke released by the cigarette itself) spreads into the surrounding air. Since these two types of smoke are produced at different combustion temperatures, each has a different composition. In sidestream smoke, the harmful substances in tobacco smoke are more highly concentrated than in the mainstream smoke inhaled by the smoker⁴. If a pregnant woman regularly inhales secondhand smoke, this can affect the unborn child through reduced birth weight and an increased risk of premature birth or miscarriage³. To keep the risk to the baby as low as possible, both parents should aim to stop smoking as early as the family planning stage.

Specific risks: premature birth, miscarriage, low birth weight, and more

Nicotine and carbon monoxide from tobacco smoke also enter the child’s bloodstream via the placenta

Smoking during pregnancy leads to an inadequate supply for your child, which comes with specific health risks. But what exactly does “inadequate supply” mean for an unborn child? For example, if an expectant mother smokes 20 cigarettes a day, by the time the baby is born it has effectively “smoked along” with 5,600 cigarettes — almost 200 packs. It is precisely this health burden that leads to risks ranging from premature birth to miscarriage. The toxins in cigarette smoke can cause ectopic pregnancies, pregnancy complications, as well as miscarriages and premature births. The risk of reduced growth in length for the baby, low birth weight and a smaller head circumference is also increased⁶.

Even after birth, the child’s health remains affected by increased risks of developmental disorders, intestinal or urinary tract infections, and congenital malformations. The smoking mother herself is also exposed to higher risks, as wound healing disorders occur more often than in non-smokers, and in some smokers the uterus has to be removed after birth⁷.

What exactly happens

• Birth weight: Babies of mothers who smoke weigh on average 200–300 grams less at birth³, as the substances in tobacco smoke impair the baby’s growth. Lower birth weight is also associated with consequences such as a smaller head circumference, reduced lung capacity, and a higher risk of infections in the first months of life.
• Premature birth: If a child is born before the 37th week of pregnancy, this is referred to as a premature birth. Children of smoking parents are 30% more likely⁸ to be born prematurely, which is associated with an increased risk of breathing difficulties and infections, as organs such as the lungs and brain are not yet fully developed.
• Miscarriage and stillbirth: The difference between a miscarriage and a stillbirth lies in the birth weight and the stage of pregnancy. If the birth weight is under 500 grams, it is considered a miscarriage; from 500 grams onward, it is considered a stillbirth. The risk for children of mothers who smoke is increased by 33 percent due to the impaired supply of nutrients⁸.
• Malformations: Children of mothers who smoke have a 13 percent higher risk of malformations⁹. The malformations most commonly caused by cigarette smoke are cleft lip and palate, congenital heart defects, malformations of the limbs, and premature closure of the cranial sutures.

Why is smoking harmful?

Long-term effects for the child: ADHD, genetic changes, and long-term risks

Does the danger to the child actually end with birth? The answer is no: Smoking during pregnancy leaves long-term effects in the child’s genetic material that may only become apparent years later. In the LiNA epidemiological study conducted by UFZ Leipzig and DKFZ Heidelberg, changes across the entire genome of children of smoking parents were identified¹⁰. As a result, these children have an increased risk of lung diseases and other health problems.

Epigenetic changes in the child’s genome

How can smoking alter genetic material without rewriting the DNA sequence itself? That is exactly what epigenetics describes. Epigenetics is the study of how environmental factors influence the activity of genes without changing the genetic code. Smoking during pregnancy has been proven to cause changes in enhancers involved in the child’s gene regulation, known as enhancers¹⁰. These enhancers are distributed throughout the entire genetic material and activate one or more genes at a specific point in time.

For different cell types, such as liver or muscle cells, to develop, certain genes need to be switched on or off at the right times. External influences such as tobacco smoke disrupt this function of the enhancers. More than 400 enhancers are affected by cigarette smoke exposure, leading to diabetes, obesity, cancer, and an increased risk of lung disease¹⁰. These epigenetic changes were detected in cord blood, which means that the gene regulation of the unborn child is already altered in the womb.

Smoking during pregnancy leaves traces in the child's genetic material

ADHD and behavioral problems

During school age and adolescence, children of smokers often show neurobiological developmental disorders such as poor concentration, learning difficulties, or hyperactivity. The risk of ADHD is around three times higher in children exposed to tobacco prenatally¹¹. Behavioral problems such as aggressive behavior, oppositional defiant behavior, or pronounced stubbornness are also observed up to three times more often in children from smoking households than in children from smoke-free households¹¹. The substances in tobacco smoke cause dysregulation of impulse and emotion control in affected children.

Sudden infant death syndrome (SIDS)

Sudden infant death syndrome, medically referred to as SIDS for Sudden Infant Death Syndrome, describes the unexpected and unexplained death of an infant or young child despite a full examination, usually occurring during sleep. Accounting for 25 percent of all deaths between one month and one year of age, SIDS is the leading cause of death in babies and young children¹². What role does tobacco smoke play here? A major one: smoking during pregnancy doubles the risk of SIDS¹². The danger to the child does not exist only during pregnancy, but also continues after birth through passive smoking.

Quitting smoking during pregnancy: stop immediately or cut down gradually?

The best thing you can do if you are pregnant and smoke is to stop smoking immediately and completely. The sooner you manage it, the better your child's developmental prospects can recover.

The myth of dangerous withdrawal

People often say that cigarette consumption should be reduced gradually during pregnancy so as not to expose the unborn child to sudden nicotine withdrawal. But this assumption is false; it is a widespread misconception¹³. The myth of dangerous withdrawal has been medically disproven; the unborn child does not suffer severe withdrawal symptoms in the womb from suddenly stopping smoking. On the contrary, the harm caused by every additional cigarette would be even more damaging to the child's health, as the transport of oxygen and nutrients would continue to be reduced. When smoking cessation succeeds, the fetus benefits immediately from the improved oxygen supply.

The mother herself may experience symptoms such as inner restlessness, irritability, or sleep disturbances during withdrawal, but these withdrawal symptoms when quitting smoking usually subside on their own after a few weeks.

What gradual reduction can do — and what it can't

That does not mean that cutting down would be pointless if a complete stop is not possible despite great effort. Every cigarette not smoked improves the fetus's chances of healthy development. However, if you reduce your smoking too slowly, you carry the craving for cigarettes around with you for weeks, and the risk of relapsing to your previous level remains — especially in stressful situations. Even the well-meant advice to simply smoke “five fewer cigarettes” per day is not enough in the long term, especially for heavy smokers⁵. During pregnancy, gradual smoking reduction should only be a short transitional phase, with the firm goal of becoming completely smoke-free soon.

If you are pregnant, you should stop smoking immediately to protect your baby.

The quit-day method as the first choice

The so-called quit-day method means stopping smoking immediately and completely from one day to the next, and it is considered an effective and healthy method for both mother and child. With this method, the unborn child is protected immediately, and its further development no longer suffers from a lack of oxygen. For the quit-day method, set a date in the near future when your smoke-free period begins. Ideally, remove all cigarettes, ashtrays, and lighters before that day so you are not tempted again. It can also help to identify typical smoking patterns (for example after meals) and deliberately plan alternatives instead of a smoking break.

more tips for quitting smoking

“I'm pregnant and I can't stop smoking” — why this is not a question of willpower

If you want to quit smoking because of your pregnancy but don't succeed right away, you are not alone. Occasional smokers often find it easier to quit, while it is often particularly difficult for heavy smokers to suddenly stop smoking completely. In this case, outside help, such as cessation programs, is an important step for the baby. Nicotine dependence is an addiction. Without nicotine, many people's bodies react with withdrawal symptoms that are often hard to manage without support.

On top of this, there is strong social pressure to stop smoking during pregnancy, along with paralyzing feelings of guilt. A US study found that only about a quarter of all pregnant smokers quit smoking completely during pregnancy¹⁴ . This result once again highlights how important professional support is if you can't quit cigarettes on your own. Getting help is nothing to be ashamed of. On the contrary: you can be proud that you want the best for yourself and your child.

You can find out more about the background of nicotine addiction and nicotine abuse in the linked articles.

Specific places to turn to

Many pregnant women report that their motivation to quit smoking is especially high during pregnancy; concern for the child often outweighs previous attempts to quit. You can use that to your advantage. Your doctor or midwife is the first and most important point of contact when it comes to quitting smoking. Integrated support services, meaning the combination of personal counselling, nicotine replacement therapy if needed, and behavioural support, are considered helpful measures for smoking cessation during pregnancy.

Here are a few specific places you can turn to:

• iris-plattform.de is a free and anonymous online counselling program that helps pregnant women stop smoking.
• rauchfrei-info.de is the independent information portal of the Federal Institute of Public Health (BIÖG) for those looking to quit smoking.
• BIÖG telephone counselling includes anonymous, free or low-cost information and counselling services on various health topics. The free service number 0800 8 31 31 31 offers active support with smoking cessation.

Methods and aids for quitting smoking during pregnancy

There are a number of approaches that can make quitting smoking easier for you. The best way to find out which individual combination suits you best is by consulting your doctor.

Behavioural methods

Behavioural therapy approaches, meaning the targeted change of habits that trigger smoking, are the first choice during pregnancy because they work completely without medication and have been proven to increase the rate of successful smoking cessation.

• Identify triggers: Triggers are automatic cues such as situations, feelings or routines that create a sudden craving for a cigarette in the brain. Common triggers include morning coffee, a break at work, mentally stressful moments or boredom. If you know your personal triggers, you can address them specifically.
• Develop alternative actions: The urge to smoke is a short-term impulse that usually lasts only a few minutes. If you keep an alternative to cigarettes ready during that time, you can often bridge the craving. For example, you can drink a glass of water, go for a short walk, or take deep breaths. The so-called 3-A technique is also often recommended. It stands for waiting, distracting yourself, and walking away. Waiting means that the craving usually passes after a few minutes, so you should simply wait it out. Distracting yourself means shifting your attention to other activities such as reading or having something to drink. And walking away means changing your location for a short while.
• Include social support: Tell your partner, your family, or your friends about your plan to quit smoking. Loved ones in your immediate circle can support you in what you’re trying to do, and at the same time you create a positive sense of commitment for yourself. This is not about being controlled by the people around you, but about emotional support and direct help in everyday life.
• Exercise: In consultation with your doctor or midwife, regular physical activity is also possible for pregnant women and can help with quitting smoking and the withdrawal symptoms that come with it¹⁵.

We have put together more psychological self-help techniques for quitting smoking in a separate guide.

Nicotine replacement therapy (NRT) during pregnancy

Nicotine replacement therapy during pregnancy is not the first choice¹⁵, but with medical supervision it can help you quit smoking for good if you find withdrawal difficult. NRT is used especially in later stages of pregnancy and for smokers who smoke more than ten cigarettes a day¹³. However, the nicotine contained in patches, gum, or lozenges is also passed on to the unborn child via the placenta with these products, although reduced birth weight has not been observed with this method¹³. The most important thing with nicotine replacement therapy during pregnancy is to consult your doctor.

Nicotine Pouches with Nicotine Polacrilex can also be used for nicotine replacement therapy. The active ingredient is the same as in gum and releases the nicotine particularly slowly. The products from the Helwit brand use only this active ingredient:

Medication-based treatment

Quitting smoking during pregnancy without medication is the option with the lowest risk for your unborn child, as there is no additional exposure to active substances via the placenta. Medications to quit smoking  with the active ingredients bupropion and varenicline, which are otherwise used for smoking cessation, are only an option under medical supervision, but are not recommended for pregnant women because only limited scientific data is available so far¹³. However, an Australian study found that using these two active ingredients in the first trimester of pregnancy hardly increases the risk of congenital malformations compared to continuing to smoke¹⁶.

E-cigarettes — not a safe alternative

E-cigarettes are not a safe Medium for quitting smoking during pregnancy. The aerosol vapor contains substances that have not yet been sufficiently researched in terms of child development and lung health. Previous animal and cell studies have shown that e-cigarettes can harm the child’s development. However, the DKFZ mentions three studies on birth weight and size under the influence of e-cigarettes that came to conflicting results¹⁷.

Is it too late? Why quitting smoking helps at any stage

Maybe your pregnancy is already further along and you're thinking: “It won’t make any difference now anyway.” But it is never too late to quit smoking during pregnancy. Giving up smoking during pregnancy reduces the negative effects on the fetus’s growth as well as on your own health, even if several weeks have already passed. Of course, the earlier you stop smoking, the better, but quitting cigarettes in the second or third trimester still offers health benefits compared to continuing to smoke.

If you stop smoking in the first trimester, the baby’s birth weight and growth can still largely return to normal. If you stop in the second trimester, you improve the baby’s lung function. And if you only aim to quit smoking in the third trimester, at least the fetus will no longer be exposed to carbon monoxide and nicotine during that time. So every smoke-free week counts.

Specifically, quitting smoking during pregnancy can lead to the following:

• The negative effects on the child’s development and growth are significantly reduced³.
• The child’s oxygen supply improves immediately due to the absence of carbon monoxide.
• The risk of premature birth is cut in half¹⁸.
• The likelihood of stillbirth is reduced by one third¹⁸.
• The chances of a healthy birth weight are higher¹⁸.
• The child’s lungs can develop fully¹⁸.
• There is a lower risk of birth complications¹⁸.
• The risk of infectious diseases later in the child’s life is reduced¹⁸.

Quitting smoking during pregnancy has many health benefits.

In recent decades, the number of pregnant women who smoke in Germany has declined significantly. While 19.6 percent of pregnant women still smoked between 1996 and 2006, the figure fell to just 10.9 percent from 2007 to 2016, meaning the share has almost halved⁷.

Can a healthy child still be born despite smoking during pregnancy?

But aren’t there also children who are still born healthy? Yes, there are babies who are born without health problems despite maternal smoking. But the risk increases with every cigarette. There is no Quantity of tobacco smoke that is considered harmless for the child. The child’s body is fighting under difficult conditions right from the start, and the individual outcome—the effects on your own child—cannot be predicted. Even if a child appears to be born unharmed, long-term damage such as learning difficulties, concentration problems, or breathing issues may only become noticeable later in the child’s life.

Maybe it helps to turn the question around: Could your child be born healthier if you stop smoking now? The answer is clear: yes. And the health risk to your child is too great to leave it to chance.

Smoking while breastfeeding — the key facts at a glance

Once the baby is born, can you start smoking again? The health risks caused by smoking do not end with birth. Cigarette smoke negatively affects the composition of breast milk. Nicotine passes directly into breast milk during breastfeeding, and an infant breaks it down three to four times more slowly than an adult¹⁹. You can find out more about how nicotine is broken down in the article “How long does nicotine stay in the body?”.

Nicotine also lowers prolactin levels, which regulate milk production and are considered a natural calming agent¹⁸. Even so, the following still applies: even for mothers who smoke, breastfeeding is better than not breastfeeding. Still, the goal should be to stop as soon as possible and no longer expose the child to harmful substances.

Medical note: This article does not replace medical advice. Nicotine is addictive. If you want to stop smoking during pregnancy or have questions about nicotine replacement products, please contact your doctor or midwife. Nicotine-containing products are not intended for pregnant women, breastfeeding women, or minors.