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From: Exposure to Psychotropic Medications and Other Substances during Pregnancy and Lactation: A Handbook for Health Care Providers

Cigarette smoke contains over 4,000 chemicals, including cyanide, aluminum, DDT, dieldrin, ammonia, arsenic, formaldehyde, benzene, hydrogen, lead, carbon monoxide, carbon dioxide, tar, chloroform and vinyl chloride.

Despite a decrease in overall smoking rates in Canada, Health Canada estimates that approximately 25 per cent of all pregnant women smoke during their pregnancies.1 Nicotine is the addictive drug found in cigarettes and has a half-life of two hours.2 Nicotine crosses the placenta easily and, unlike most drugs (which maintain similar maternal and fetal concentrations), fetal concentrations of nicotine are generally 15 per cent higher than maternal levels.3

Summary and Recommendations

  • Cigarette smoking is highly addictive. Despite knowing smoking is harmful during pregnancy and breastfeeding, and despite making an effort, some women are unable to quit. These women should be encouraged to undergo smoking cessation therapy (e.g., nicotine patch, nicotine gum, counselling). If such therapy is unsuccessful, a harm reduction approach is suggested. The mother should be encouraged to reduce the number of cigarettes smoked each day as much as possible, as there is a correlation between dose and fetal/neonatal response (i.e., the more cigarettes smoked, the more potential harm to the fetus or baby).
  • If the mother can abstain from smoking for four-hour intervals (i.e., approximately two nicotine half-lives), nicotine concentrations would be expected to fall to one-quarter of their initial level. This means less nicotine and other harmful substances will enter the breast milk.
  • To avoid second-hand smoke entering the child’s system, no one should ever smoke near the baby.

Fetal effects

Smoking has an adverse effect on fetal growth, and is associated with premature birth and low birth weight. A mean decrease in birth weight of 200 grams is usually associated with babies whose mothers smoked while pregnant.4

Preterm premature rupture of membranes has been shown to occur more frequently (1.4 per cent) in women who smoked 20 or more cigarettes per day during pregnancy, while the rate dropped to 0.6 per cent in women who smoked one to five cigarettes per day and to 0.3 per cent in non-smokers.5

In addition, a meta-analysis of 13 observational studies (seven case-control and six cohort studies) found that smoking is associated with a two-fold increase in the risk of placental abruptions.6

Major malformations

Smoking has not been associated with an increased risk of major malformations.

Spontaneous abortion

Prenatal exposure to tobacco is associated with an increased risk of spontaneous abortion.4

Neonatal effects

Studies have reported on the neurotoxic effects of prenatal tobacco exposure, passive addiction and neonatal nicotine withdrawal syndrome (NNWS) in newborns exposed in utero to maternal smoking. NNWS is characterized by irritability, tremors and sleep disturbances, most typically observed in newborns of mothers who smoke heavily.7

Also, in a large prospective follow-up study of 24,986 participants, the risk of sudden infant death syndrome (SIDS) was three times higher in children born to mothers who smoked. In addition, the risk of SIDS increased with the number of cigarettes a woman smoked each day during pregnancy, with the greatest risk associated with 10 or more cigarettes smoked daily.8

Second-hand smoke must also be taken into account as a health risk to the newborn.

Long-term effects on the child

A study of 5,636 adult men found that, compared to the sons of women who did not smoke while pregnant, those whose mothers did smoke while pregnant had more than a two-fold greater risk of committing a violent crime, or repeatedly committing crimes, even when other biopsychosocial risk factors were controlled.9


Women who breastfeed and smoke have lower basal prolactin levels, which may lead to a decrease in their milk supply. One study suggests that cigarette smoking significantly reduces breast milk production at two weeks postpartum (i.e., from 514 millilitres per day in mothers who do not smoke to 406 millilitres per day in mothers who do smoke).10 However, another more recent study detected no change in milk production of mothers who smoked and breastfed their babies.11

Although the effects of nicotine are dose dependent, the potential long-term effects on infants exposed to nicotine via breast milk are unknown.

Nicotine is only one component of cigarette smoke; the potential adverse effects on the infant from exposure to the thousands of other chemicals present in cigarette smoke and their passage into breast milk are unknown.

Withdrawal effects on the mother

About 20 percent of people who have established a smoking habit (i.e., smoking on a daily basis for one month) develop nicotine dependence.12,13 Symptoms of nicotine withdrawal include irritability, restlessness, anxiety, insomnia and fatigue. While these symptoms vanish within a couple of weeks, some people may be unable to concentrate, and have strong cravings to smoke, for weeks or months after quitting smoking.


  1. Health Canada. (2005). Healthy Living: Smoking and Your Body—Pregnancy. Available: body-corps/preg-gros/index_e.html. Accessed July 10, 2007.
  2. Society for Clinical Preventative Health Care. (n.d.). Clinical Tobacco Intervention Recognition Program. Vancouver: Author. Available: 12stopsmokingmedications.html. Accessed July 13, 2007.
  3. Lambers, D.S. & Clark, K.E. (1996). The maternal and fetal physiologic effects of nicotine. Seminars in Perinatology, 20 (2), 115–126.
  4. Pollack, H., Lantz, P.M. & Frohna, J.G. (2000). Maternal smoking and adverse birth outcomes among singletons and twins. American Journal of Public Health, 90 (3), 395–400.
  5. Castles, A., Adams, E.K., Melvin, C.L., Kelsch, C. & Boulton, M.L. (1999). Effects of smoking during pregnancy: Five meta-analyses. American Journal of Preventive Medicine, 16 (3), 208–215.
  6. Ananth, C.V., Smulian, J.C. & Vintzileos, A.M. (1999). Incidence of placental abruption in relation to cigarette smoking and hypertensive disorders during pregnancy: A meta-analysis of observational studies. Obstetrics and Gynecology, 93 (4), 622–628.
  7. Pichini, S. & Garcia-Algar, O. (2006). In utero exposure to smoking and newborn neurobehavior: How to assess neonatal withdrawal syndrome? Therapeutic Drug Monitoring, 28 (3), 288–290.
  8. Wisborg, K., Kesmodel, U., Henriksen, T.B., Olsen, S.F. & Secher, N.J. (2000). A prospective study of smoking during pregnancy and SIDS. Archives of Disease in Childhood, 83 (3), 203–206.
  9. Räsänen, P., Hakko, H., Isohanni, M., Hodgins, S., Järvelin, M. & Tiihonen, J. (1999). Maternal smoking during pregnancy and risk of criminal behavior among adult male offspring in the Northern Finland 1966 Birth Cohort. American Journal of Psychiatry, 156 (6), 857–862.
  10. Ilett, K.F., Hale, T.W., Page-Sharp, M., Kristensen, J.H., Kohan, R. & Hackett, L.P. (2003). Use of nicotine patches in breast-feeding mothers: Transfer of nicotine and cotinine into human milk. Clinical Pharmacology and Therapeutics, 74 (6), 516–524.
  11. Hopkinson, J.M., Schanler, R.J., Fraley, J.K. & Garza, C. (1992). Milk production by mothers of premature infants: Influence of cigarette smoking. Pediatrics, 90 (6), 934–938.
  12. Breslau, N., Johnson, E.O., Hiripi, E. & Kessler, R. (2001). Nicotine dependence in the United States: Prevalence, trends, and smoking persistence. Archives of General Psychiatry, 58 (9), 810–816.
  13. Kessler, D.A, Natanblut, S.L., Wilkenfeld, J.P., Lorraine, C.C., Mayl, S.L., Bernstein, I.B. et al. (1997). Nicotine addiction: A pediatric disease. Journal of Pediatrics, 130 (4), 518–524.

Exposure to Psychotropic Medications and Other Substances during Pregnancy and Lactation: A Handbook for Health Care Providers

General issues and background

Psychotropic medications and other substances: Properties, effects and recommendations


Index of drugs

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