Smoking and pregnancy

Pregnant woman smoking outside a London hospital

Tobacco smoking and pregnancy is related to many effects on health and reproduction, in addition to the general health effects of tobacco. A number of studies have shown that tobacco use is a significant factor in miscarriages among pregnant smokers, and that it contributes to a number of other threats to the health of the fetus.[1][2]

Ideally, women should not smoke before, during or after pregnancy. If this is not the case, however, the daily number of cigarettes can be reduced to minimize the risks for both the mother and child. This is particularly important for women in developing countries where breastfeeding is essential for the child’s overall nutritional status.[3]

Smoking before pregnancy

It is important to examine these effects because smoking before, during and after pregnancy is not an unusual behavior among the general population and can have detrimental health impacts, especially among both mother and child as a result. In 2011, approximately 10% of pregnant women in data collected from 24 states reported smoking during the last three months of their pregnancy.[4]

Smoking during pregnancy

In the United States today, approximately 10% of women smoke during pregnancy. Of women who smoked during the last 3 months of pregnancy, 52% reported smoking 5 or fewer cigarettes per day, 27% reported smoking 6 to 10 cigarettes per day, and 21% reported smoking 11 or more cigarettes per day.

In the United States, women whose pregnancies were unintended are 30% more likely to smoke during pregnancy than those whose pregnancies were intended.[5]

Effects on ongoing pregnancy

Smoking during pregnancy can lead to a plethora of health risks to both the mother and the fetus.

Women who smoke during pregnancy are about twice as likely to experience the following pregnancy complications:[6]

Premature birth

Some studies show that the probability of premature birth is roughly 1% higher for women who smoke during pregnancy going from around -1% to 1%.[8]

Implications for the umbilical cord

Smoking can also impair the general development of the placenta, which is problematic because it reduces blood flow to the foetus. When the placenta does not develop fully, the umbilical cord which transfers oxygen and nutrients from the mother's blood to the placenta, cannot transfer enough oxygen and nutrients to the foetus, which will not be able to fully grow and develop. These conditions can result in heavy bleeding during delivery that can endanger mother and baby, although cesarean delivery can prevent most deaths.[9]

Pregnancy-induced hypertension

There is limited evidence that smoking reduces the incidence of pregnancy-induced hypertension,[10] but not when the pregnancy is with more than one baby (i.e. it has no effect on twins etc.).[11]

Effects of smoking during pregnancy on the child after birth

Low birthweight

Smoking nearly doubles the risk of low birthweight babies. In 2004, 11.9% of babies born to smokers had low birthweight as compared to only 7.2% of babies born to nonsmokers. More specifically, infants born to smokers weigh on average 200 grams less than infants born to women who do not smoke. Premature and low birthweight babies face an increased risk of serious health problems as newborns have chronic lifelong disabilities such as cerebral palsy (a set of motor conditions causing physical disabilities), mental retardation and learning problems. Overall, they also face an increased risk of death.

Sudden infant death syndrome

Sudden infant death syndrome (SIDS) is the sudden death of an infant that is unexplainable by the infant’s history. The death also remains unexplainable upon autopsy. Infants exposed to smoke, both during pregnancy and after birth, are found to be more at risk of SIDS due to the increased levels of nicotine often found in SIDS cases. Infants exposed to smoke during pregnancy are up to three times more likely to die of SIDS that children born to non-smoking mothers. [12]

Other birth defects

Birth defects associated with smoking during pregnancy[13]
Defect Odds ratio
cardiovascular/heart defects 1.09
musculoskeletal defects 1.16
limb reduction defects 1.26
missing/extra digits 1.18
clubfoot 1.28
craniosynostosis 1.33
facial defects 1.19
eye defects 1.25
orofacial clefts 1.28
gastrointestinal defects 1.27
gastroschisis 1.50
anal atresia 1.20
hernia 1.40
undescended testes 1.13
hypospadias 0.90
skin defects 0.82
All defects combined 1.01

Smoking can also cause other birth defects, reduced birth circumference, altered brainstem development, altered lung structure, and cerebral palsy. Recently the U.S. Public Health Service reported that if all pregnant women in the United States stopped smoking, there would be an estimated 11% reduction in stillbirths and a 5% reduction in newborn deaths.

Future obesity

A recent study has proposed that maternal smoking during pregnancy can lead to future teenage obesity. While no significant differences could be found between young teenagers with smoking mothers as compared to young teenagers with nonsmoking mothers, older teenagers with smoking mothers were found to have on average 26 percent more body fat and 33 percent more abdominal fat than similar aged teenagers with non-smoking mothers. This increase in body fat may result from the effect smoking during pregnancy, which is thought to impact fetal genetic programming in relation to obesity. While the exact mechanism for this difference is currently unknown, studies conducted on animals have indicated that nicotine may affect brain functions that deal with eating impulses and energy metabolism. These differences appear to have a significant effect on the maintenance of a healthy, normal weight. As a result of this alteration to brain functions, teenage obesity can in turn lead to a variety of health problems including diabetes (a condition in which the affected individual’s blood glucose level is too high and the body is unable to regulate it), hypertension (high blood pressure), and cardiovascular disease (any affliction related to the heart but most commonly the thickening of arteries due to excess fat build-up).[14]

Future smoking habits

Studies indicate that smoking during pregnancy increases the likelihood of offspring beginning to smoke at an early age.

Quitting during pregnancy

Quitting smoking at any point during pregnancy is more beneficial than continuing to smoke throughout the entire 9 months of pregnancy, especially if it is done within the first trimester (within the first 12 weeks of pregnancy). A recent study suggests, however, that women who smoke anytime during the first trimester put their fetus at a higher risk for birth defects, particularly congenital heart defects (structural defects in the heart of an infant that can hinder blood flow) than women who have never smoked. That risk only continues to increase the longer into the pregnancy a woman smokes, as well as the larger number of cigarettes she is smoking. This continued increase in risk throughout pregnancy means that it can still be beneficial for a pregnant woman to quit smoking for the remainder of her gestation period.[9]

There are many resources to help pregnant women quit smoking such as counseling and drug therapies. For non-pregnant smokers, an often-recommended aid to quitting smoking is through the use of Nicotine replacement therapy in the form of patches, gum, inhalers, lozenges, sprays or sublingual tablets (tablets which you place under the tongue). However, it is important to note that the use of Nicotine Replacement Therapies (NRTs) is questionable for pregnant women as these treatments still deliver nicotine to the child. For some pregnant smokers, NRT might still be the most beneficial and helpful solution to quit smoking. It is important to talk to your doctor to determine the best course of action on an individual basis.[15]

Smoking after pregnancy

Infants exposed to smoke, both during pregnancy and after birth, are found to be more at risk of sudden infant death syndrome (SIDS).[12]

Breastfeeding

If one does continue to smoke after giving birth, however, it is still more beneficial to breastfeed than to completely avoid this practice altogether. There is evidence that breastfeeding offers protection against many infectious diseases, especially diarrhea. Even in babies exposed to the harmful effects of nicotine through breast milk, the likelihood of acute respiratory illness is significantly diminished when compared to infants whose mothers smoked but were formula fed.[16] Regardless, the benefits of breastfeeding outweigh the risks of nicotine exposure.

Passive smoking

Passive smoking is associated with many risks to children, including, sudden infant death syndrome (SIDS),[17][18] asthma,[19][20] lung infections,[21][22][23][24] impaired respiratory function and slowed lung growth,[6] Crohn's disease,[25] learning difficulties and neurobehavioral effects,[26][27] an increase in tooth decay,[28] and an increased risk of middle ear infections.[29][30]

See also

References

  1. ↑ Ness, Roberta B.; Grisso, Jeane Ann; Hirschinger, Nancy; Markovic, Nina; Shaw, Leslie M.; Day, Nancy L.; Kline, Jennie (1999). "Cocaine and Tobacco Use and the Risk of Spontaneous Abortion". New England Journal of Medicine 340 (5): 333–9. doi:10.1056/NEJM199902043400501. PMID 9929522.
  2. ↑ Oncken, Cheryl; Kranzler, Henry; O'Malley, Paulette; Gendreau, Paula; Campbell, Winston (2002). "The effect of cigarette smoking on fetal heart rate characteristics". Obstetrics and Gynecology 99 (5 Pt 1): 751–5. doi:10.1016/S0029-7844(02)01948-8. PMID 11978283.
  3. ↑ Najdawi, F; Faouri, M (1999). "Maternal smoking and breastfeeding". Eastern Mediterranean Health Journal 5 (3): 450–6. PMID 10793823.
  4. ↑ http://www.cdc.gov/reproductivehealth/tobaccousepregnancy[]
  5. ↑ Eisenberg, Leon; Brown, Sarah Hart (1995). The best intentions: unintended pregnancy and the well-being of children and families. Washington, D.C: National Academy Press. pp. 68–70. ISBN 0-309-05230-0.
  6. 1 2 Centers for Disease Control and Prevention. 2007. Preventing Smoking and Exposure to Secondhand Smoke Before, During, and After Pregnancy.
  7. ↑ MedlinePlus Encyclopedia Placenta previa
  8. ↑ Anderka, Marlene; Romitti, Paul A.; Sun, Lixian; Druschel, Charlotte; Carmichael, Suzan; Shaw, Gary (2010). "Patterns of tobacco exposure before and during pregnancy". Acta Obstetricia et Gynecologica Scandinavica 89 (4): 505–14. doi:10.3109/00016341003692261. PMID 20367429.
  9. 1 2 Vardavas, Constantine I.; Chatzi, Leda; Patelarou, Evridiki; Plana, Estel; Sarri, Katerina; Kafatos, Anthony; Koutis, Antonis D.; Kogevinas, Manolis (2010). "Smoking and smoking cessation during early pregnancy and its effect on adverse pregnancy outcomes and fetal growth". European Journal of Pediatrics 169 (6): 741–8. doi:10.1007/s00431-009-1107-9. PMID 19953266.
  10. ↑ Zhang, Jun; Zeisler, Jonathan; Hatch, Maureen C.; Berkowitz, Gertrud (1997). "Epidemiology of Pregnancy-induced Hypertension". Epidemiologic Reviews 19 (2): 218–32. PMID 9494784.
  11. ↑ Krotz, Stephan; Fajardo, Javier; Ghandi, Sanjay; Patel, Ashlesha; Keith, Louis G. (2002). "Hypertensive Disease in Twin Pregnancies: A Review". Twin Research 5 (1): 8–14. doi:10.1375/1369052022848. PMID 11893276.
  12. 1 2 Bajanowski, T.; Brinkmann, B.; Mitchell, E. A.; Vennemann, M. M.; Leukel, H. W.; Larsch, K.-P.; Beike, J. (2008). "Nicotine and cotinine in infants dying from sudden infant death syndrome". International Journal of Legal Medicine 122 (1): 23–8. doi:10.1007/s00414-007-0155-9. PMID 17285322.
  13. ↑ Unless else specified in table, then reference is: Hackshaw, A.; Rodeck, C.; Boniface, S. (2011). "Maternal smoking in pregnancy and birth defects: a systematic review based on 173 687 malformed cases and 11.7 million controls". Human Reproduction Update 17 (5): 589–604. doi:10.1093/humupd/dmr022. PMC 3156888. PMID 21747128.
  14. ↑ Nguyen, Linda. "Teen Obesity Linked to Pre-birth Tobacco Exposure: Study." The Gazette. Canwest News Service, 27 April 2010. Web. 27 April 2010. <http://www.montrealgazette.com/health/Teen+obesity+linked+birth+tobacco+exposure+Study/2956850/story.html>
  15. ↑ March, Penny D., and Carita Caple. "Smoking Cessation and Pregnancy." Ed. Diane Pravikoff. Cinahl Information Systems (2010). Print.
  16. ↑ Mennella, J. A.; Yourshaw, L. M.; Morgan, L. K. (2007). "Breastfeeding and Smoking: Short-term Effects on Infant Feeding and Sleep". Pediatrics 120 (3): 497–502. doi:10.1542/peds.2007-0488. PMC 2277470. PMID 17766521.
  17. ↑ McMartin, Kristen I.; Platt, Marvin S.; Hackman, Richard; Klein, Julia; Smialek, John E.; Vigorito, Robert; Koren, Gideon (2002). "Lung tissue concentrations of nicotine in sudden infant death syndrome (SIDS)". The Journal of Pediatrics 140 (2): 205–9. doi:10.1067/mpd.2002.121937. PMID 11865272.
  18. ↑ Milerad, Joseph; Vege, Åshild; Opdal, Siri H.; Rognum, Torleiv O. (1998). "Objective measurements of nicotine exposure in victims of sudden infant death syndrome and in other unexpected child deaths". The Journal of Pediatrics 133 (2): 232–6. doi:10.1016/S0022-3476(98)70225-2. PMID 9709711.
  19. ↑ Surgeon General 2006, pp. 311–9
  20. ↑ Blaisdell, Robert J.; Broadwin, Rachel L.; Vork, Kathleen L. (2007). "Developing Asthma in Childhood from Exposure to Second-hand Tobacco Smoke - Insights from a Meta-Regression". Environmental Health Perspectives 115 (10): 1394–400. doi:10.1289/ehp.10155. PMC 2022647. PMID 17938726.
  21. ↑ Spencer, N; Coe, C (2003). "Parent reported longstanding health problems in early childhood: a cohort study". Archives of Disease in Childhood 88 (7): 570–3. doi:10.1136/adc.88.7.570. PMC 1763148. PMID 12818898.
  22. ↑ de Jongste JC, Shields MD (2003). "Cough . 2: Chronic cough in children". Thorax 58 (11): 998–1003. doi:10.1136/thorax.58.11.998. PMC 1746521. PMID 14586058.
  23. ↑ Dybing, E.; Sanner, T. (1999). "Passive smoking, sudden infant death syndrome (SIDS) and childhood infections". Human & Experimental Toxicology 18 (4): 202–5. doi:10.1191/096032799678839914. PMID 10333302.
  24. ↑ DiFranza, Joseph R.; Aligne, C. Andrew; Weitzman, Michael (2004). "Prenatal and Postnatal Environmental Tobacco Smoke Exposure and Children’s Health". Pediatrics 113 (4 Suppl): 1007–15. doi:10.1542/peds.113.4.S1.1007 (inactive August 15, 2015). PMID 15060193.
  25. ↑ Mahid, Suhal S.; Minor, Kyle S.; Stromberg, Arnold J.; Galandiuk, Susan (2007). "Active and Passive Smoking in Childhood Is Related to the Development of Inflammatory Bowel Disease". Inflammatory Bowel Diseases 13 (4): 431–8. doi:10.1002/ibd.20070. PMID 17206676.
  26. ↑ Richards, GA; Terblanche, AP; Theron, AJ; Opperman, L; Crowther, G; Myer, MS; Steenkamp, KJ; Smith, FC; Dowdeswell, R; van der Merwe, CA; Stevens, K; Anderson, R (1996). "Health effects of passive smoking in adolescent children". South African Medical Journal 86 (2): 143–7. PMID 8619139.
  27. ↑ Scientific Consensus Statement on Environmental Agents Associated with Neurodevelopmental Disorders, The Collaborative on Health and the Environment’s Learning and Developmental Disabilities Initiative, November 7, 2007
  28. ↑ Avşar, A.; Darka, Ö.; Topaloğlu, B.; Bek, Y. (2008). "Association of passive smoking with caries and related salivary biomarkers in young children". Archives of Oral Biology 53 (10): 969–74. doi:10.1016/j.archoralbio.2008.05.007. PMID 18672230.
  29. ↑ Surgeon General 2006, pp. 293–309
  30. ↑ Jacoby, Peter A; Coates, Harvey L; Arumugaswamy, Ashwini; Elsbury, Dimity; Stokes, Annette; Monck, Ruth; Finucane, Janine M; Weeks, Sharon A; Lehmann, Deborah (2008). "The effect of passive smoking on the risk of otitis media in Aboriginal and non-Aboriginal children in the Kalgoorlie–Boulder region of Western Australia". The Medical Journal of Australia 188 (10): 599–603. PMID 18484936.

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