[Note: This article is being published in draft form for use in an active research study. Its contents may be adjusted as we receive feedback from collaborating health care professionals.]
A World Health Organization (WHO) report from 2021 advises for strong tobacco control measures and outlines the devastating impacts smoke has on infants and children.1 According to the WHO, exposure to second hand smoke during pregnancy can lead to preterm birth and low birth weight. The advisory also states that children living with smokers are at increased risk of infections such as bronchiolitis, middle ear disease, pneumonia and other respiratory infections. They also report that children are at increased risk of poor school performance or behavioral difficulties. Lastly, they report increased risk of asthma and risk of death before age 5. The Unit Head at Child Health and Development at the WHO Department of Maternal, Newborn, Child, and Adolescent Health and Aging states, “There is no safe level of exposure to tobacco smoke. It seriously harms the health of a child.”
A cross-sectional study published in 2010 looked at the relationship between maternal secondhand smoke (SHS) exposure during pregnancy and adverse pregnancy outcomes.2 This study administered surveys to 8,490 women within 24 hours of delivery. Women who reported active smoking during pregnancy were excluded. This study found that 12.6% of babies from mothers exposed to SHS during pregnancy had low birth weight, defined as <2.5 kg, compared to 7.7% of babies from non-exposed mothers. The average birth weight for newborns of women exposed to SHS was 3.06 kg, as compared to 3.2 kg for babies from unexposed women (p <0.005). The rate of preterm delivery in mothers exposed to SHS during pregnancy was 17.2%, as compared to 10.6% in the non-exposed group. The average gestational age for exposed women was 36.9 weeks, as compared to 37.7 weeks in the non-exposed group (p <0.005).
A study from 2017 included 813 mother-offspring pairs from the longitudinal Healthy Start study.3 At 5 months of age, mothers were interviewed to collect information regarding infant SHS exposure and other infant characteristics. Like the previously mentioned study, this study found that the average gestational age at delivery was higher in women without household SHS exposure during pregnancy compared to women with household smokers (average 40 weeks gestational age for 684 non-exposed vs average 39 weeks for 129 exposed, p = 0.03). Additionally, infants born to women with no household smoke exposure weighed on average 3.3 kg at birth, as compared to 3.1 kg in the exposed group (p< 0.01).
A meta-analysis published in 2012 evaluated the relationship between sudden infant death syndrome (SIDS) and both prenatal and postnatal maternal smoking.4 35 case-control studies including 21,040 cases and 5,956,030 controls across the world were included in the meta-analysis. The meta-analysis found higher rates of exposure to smoke in the group of infants who died of SIDS. Of infants who died of SIDS, 33% (9,096/27,349) had mothers who smoked while pregnant. Of the infants who did not have SIDS, 13% (67,2447/5,180,605) experienced prenatal maternal smoking. Of infants with SIDS, 55% (2,293/4,170) had mothers who smoked after pregnancy. Of the infants without SIDS, 28% (222,368/785,742) were exposed to SHS as babies.
A study from 2014 looked at associations between asthma development in children and maternal smoking or home SHS exposure during pregnancy.5 The study included a population-based cohort of 5,619 seven-year-old children living in Toronto. Parents filled out surveys pertaining to age of asthma diagnosis, maternal smoking during pregnancy, home second-hand smoke exposure from pregnancy until 7 years, and family history of atopy. Results showed that 846 out of all 5619 children (15.5%) developed asthma. After adjusting for sex, preterm birth, maternal asthma, and breastfeeding duration, maternal active smoking or home second-hand smoke exposure during pregnancy was associated with a 30% increased adjusted hazard of childhood asthma development (adjusted hazard ratio [HR] 1.30, 95% CI 1.06-1.60). The association between physician-diagnosed childhood asthma and maternal home second-hand smoke exposure persisted in children without active maternal smoking during pregnancy (adjusted HR 1.34, 95% CI 1.01-1.76).
A prospective, population-based birth cohort study from 2001 studied the relationship between SHS exposure and utilization of health services within the first 18 months of life.6 8,327 parent-infant pairs were followed for 18 months. 18.7% of infants born to mothers exposed to SHS during pregnancy had high hospital utilization (defined as above the median number of hospitalizations within the study sample), as compared to 16.8% of infants born to non-exposed mothers (p = 0.037). Similarly, 29.6% of infants born to mothers exposed to SHS during pregnancy had high hospital utilization for any illness, as compared to 26% in the non-exposed group (p <0.001). They also evaluated the relationship between postnatal SHS and hospitalization rates. 19.5% of infants exposed to SHS by individuals at home had high hospital utilization for respiratory illness, as compared to 17.1% of non-exposed infants (p = 0.009). 30.6% of infants exposed to SHS at home had high hospital utilization for any type of illness, compared to 27% for non-exposed infants (<0.001). This study also observed a dose-response gradient between the total number of smokers at home and increased hospitalizations. 21.7% of infants with 2 or more smokers at home had high hospital utilization for respiratory illnesses, as compared to 18.9% of infants with 1 smoker at home (p = 0.01). Similarly, 34.6% of infants with 2 or more smokers at home had high hospital utilization for any type of illness, as compared to 29.4% with 1 smoker at home (p <0.001).
A case-control study in 1999 looked specifically into the relationship between SHS and ear infections.7 In this study, 166 children who required tympanostomy tubes for otitis media with effusion or recurrent otitis media were compared to an age-matched control group of 166 children without tympanostomy tubes. The study found that the children with tympanostomy tubes were exposed to an average of 19.6 cigarettes per day, compared to 14.4 cigarettes in the control group (p<0.004).
A prospective study from 2011 evaluated the effects of prenatal and postnatal secondhand smoke exposure on neurodevelopment in babies at 6 months old.8 The study included 414 healthy mother and infant pairs from the Mother’s and Children’s Environmental Study. Women who actively smoked during pregnancy were excluded from this study. The study obtained information about maternal SHS exposure during pregnancy through questionnaires and infant development at 6 months through assessments using the Bayley Scales of Infant Development assessment, performed by a blinded evaluator. The standardized mean score is 100 with a standard deviation of 15. Scores <85 indicate developmental delay. The study found that for the average Mental Developmental Index (MDI) score was 98.2 in the group without prenatal smoke exposure (n= 151), compared to 95.67 in the prenatally exposed group (n = 263). Of note, the rate of moderate developmental delay was 10.6% in the prenatal unexposed group, as compared to 19.0% in the prenatal exposed cohort (p <0.05). The average MDI score was 96.52 for the postnatal unexposed group (n = 201), as compared to 98.03 in the postnatal unexposed group (n = 126. The study concluded that infants of non-smoking women exposed to secondhand smoke may be at increased risk of developmental delay.
A systematic review and meta-analysis done in 2017 looked at the impact of environmental tobacco smoke exposure on anesthetic outcomes in 0–18-year-olds.9 More specifically, they investigated rates of respiratory adverse events (RAEs) while under anesthesia, including laryngospasm, breath holding, bronchospasm, hypersecretion, obstruction, cough, and desaturation. 28 cohort and case-control studies were included. This study found that children with environmental tobacco exposure had higher rates of RAEs compared to children without second-hand smoke exposure [17% (78/456) of ETS exposed had RAEs vs 9.5% (70/736) of children not exposed had RAEs, p = 0.03].
References
- Dalia Lourenço LK. New brief outlines devastating harms from tobacco use and exposure to second-hand tobacco smoke during pregnancy and throughout childhood - Report calls for protective policies.
- Khader YS, Al-Akour N, Alzubi IM, Lataifeh I. The association between second hand smoke and low birth weight and preterm delivery. Matern Child Health J. May 2011;15(4):453-9. doi:10.1007/s10995-010-0599-2
- Moore BF, Sauder KA, Starling AP, Ringham BM, Glueck DH, Dabelea D. Exposure to secondhand smoke, exclusive breastfeeding and infant adiposity at age 5 months in the Healthy Start study. Pediatr Obes. Aug 2017;12 Suppl 1(Suppl 1):111-119. doi:10.1111/ijpo.12233
- Zhang K, Wang X. Maternal smoking and increased risk of sudden infant death syndrome: a meta-analysis. Leg Med (Tokyo). May 2013;15(3):115-21. doi:10.1016/j.legalmed.2012.10.007
- Simons E, To T, Moineddin R, Stieb D, Dell SD. Maternal second-hand smoke exposure in pregnancy is associated with childhood asthma development. J Allergy Clin Immunol Pract. Mar-Apr 2014;2(2):201-7. doi:10.1016/j.jaip.2013.11.014
- Lam TH, Leung GM, Ho LM. The effects of environmental tobacco smoke on health services utilization in the first eighteen months of life. Pediatrics. Jun 2001;107(6):E91. doi:10.1542/peds.107.6.e91
- Ilicali OC, Keleş N, Değer K, Savaş I. Relationship of passive cigarette smoking to otitis media. Arch Otolaryngol Head Neck Surg. Jul 1999;125(7):758-62. doi:10.1001/archotol.125.7.758
- Lee BE, Hong YC, Park H, et al. Secondhand smoke exposure during pregnancy and infantile neurodevelopment. Environ Res. May 2011;111(4):539-44. doi:10.1016/j.envres.2011.02.014
- Chiswell C, Akram Y. Impact of environmental tobacco smoke exposure on anaesthetic and surgical outcomes in children: a systematic review and meta-analysis. Arch Dis Child. Feb 2017;102(2):123-130. doi:10.1136/archdischild-2016-310687
