Stopping Smoking in Pregnancy: What the Evidence Says

If you are pregnant and trying to stop smoking, the first thing to do is tell your midwife or doctor. They can refer you to NHS stop smoking services, which are free and have specially trained advisors for pregnancy. This page is information, not a substitute for that conversation.

What happens when you stop smoking during pregnancy

Nicotine leaves the body quickly. The half-life of nicotine is about two hours, meaning that within a day or two most of it is gone. What remains is the habit and the withdrawal.

Withdrawal from nicotine peaks in the first three days and generally eases over two to four weeks. Common symptoms include irritability, restlessness, difficulty concentrating, increased appetite, and disturbed sleep. These are not signs of failure. They are the expected response of a nervous system that has adapted to regular nicotine.

In pregnancy, the body is already changing. Blood volume increases, metabolism speeds up, and nicotine is cleared faster than usual. That can mean withdrawal symptoms arrive sooner and feel sharper. It does not mean quitting is harder in pregnancy than at other times; it means the timeline may be different.

Carbon monoxide from cigarettes reduces the oxygen available to the placenta. When smoking stops, carbon monoxide levels in the blood fall to normal within 24 to 48 hours. This is a measurable change, not a promise about outcomes.

Nicotine replacement therapy in pregnancy: what the trials found

The evidence on NRT in pregnancy is more nuanced than either the ‘it’s safe, use it’ or ‘it’s unsafe, avoid it’ positions suggest.

A Cochrane review of randomised controlled trials, published in 2020, examined nicotine replacement therapy for smoking cessation in pregnancy. It found that NRT, when used alongside behavioural support, may help some pregnant women stop smoking. The evidence was moderate quality. The review did not find clear evidence of harm to the fetus from NRT, but it also did not find strong evidence of benefit for all women.

The National Institute for Health and Care Excellence (NICE) recommends that pregnant women who smoke should be offered NRT if they are unable to stop with behavioural support alone. NICE notes that the decision should be made with a healthcare professional, taking into account the woman’s preferences and circumstances.

NRT delivers nicotine without the carbon monoxide and other toxins in cigarette smoke. That is the rationale. But nicotine itself is not inert; it affects blood vessels and may have effects on the developing fetus. The trials have not shown a clear increase in adverse outcomes, but they are not large enough to rule out small risks.

The practical position, according to NICE and the NHS, is that NRT is considered safer than continued smoking in pregnancy. That is a comparative judgement, not a guarantee of safety. The decision about whether to use NRT, and which form, belongs to the pregnant person and their doctor or midwife.

Prescription medicines: what is known

Bupropion and varenicline are prescription medicines used for smoking cessation outside pregnancy. There is limited evidence about their use in pregnancy.

Varenicline (trade name Champix) works by reducing cravings and the pleasurable effects of smoking. Trials in non-pregnant adults found it more effective than placebo. In pregnancy, the data are sparse. A small number of observational studies have not shown a clear pattern of birth defects, but they cannot rule out risk. Varenicline is not licensed for use in pregnancy in the UK.

Bupropion is an antidepressant that also reduces cravings. It is not recommended in pregnancy because of limited data.

Neither medicine is a first-line option in pregnancy. The decision to use any prescription medicine during pregnancy is between the patient and their doctor. This page does not instruct anyone to start, stop, or switch any medicine.

Behavioural support: what is available

NHS stop smoking services offer free, one-to-one support for pregnant women. Advisors are trained to work with pregnancy and can provide NRT if appropriate. They can also offer carbon monoxide monitoring, which gives feedback on progress.

Referral is usually through a midwife or GP. Some services accept self-referral. The support typically involves weekly sessions, either in person or by phone, for several weeks.

Behavioural support alone has been shown in trials to help some pregnant women stop smoking. The effect is modest. It is not a cure, and it does not work for everyone.

Hypnosis and other remedies

Hypnosis is sometimes suggested as a way to stop smoking in pregnancy. A Cochrane review of hypnotherapy for smoking cessation found no clear evidence that it performs better than other interventions. The trials were small and varied in quality. That does not mean hypnosis cannot help an individual; it means the evidence does not show it works better than other methods.

Acupuncture, acupressure, and laser therapy have also been studied. A Cochrane review found insufficient evidence to determine whether these are effective for smoking cessation in pregnancy.

There is no remedy that has been proven to work for everyone. Anyone who says otherwise is selling something.

What to expect in the first weeks

The first three days are often the most uncomfortable. Irritability, cravings, and difficulty sleeping are common. After that, symptoms tend to gradually reduce. By two to four weeks, most physical withdrawal symptoms have eased. Cravings can still occur, often triggered by habit or stress, but they typically become less frequent and less intense.

Sleep disturbance is common in pregnancy anyway. Nicotine withdrawal can add to it. This is not a sign that quitting is harming the pregnancy; it is a sign that the body is adjusting.

Appetite often increases. Some people gain weight. In pregnancy, weight gain is expected. The evidence does not support restricting food intake during pregnancy.

If you have tried before and it did not work

Many people try several times before they stop smoking. That is the normal pattern, not a personal failing. Each attempt provides information about what triggers cravings and what support helps.

If you have tried before, the next attempt can include a plan for those triggers. That might mean avoiding certain situations, using NRT, or having a specific person to call. It does not have to be a solo effort.

What this page is not

This page does not promise that any method will work. It does not say that stopping smoking is easy. It does not use fear to motivate. It does not tell anyone what to do about prescription medicines.

What it does is describe what the evidence says, name the sources, and point to support. The rest is between the reader and their healthcare team.