The independent effects of second hand smoke exposure and maternal body mass index on the anthropometric measurements of the newborn

Abstract

BackgroundExposure to tobacco smoke during pregnancy, whether as active smoking or by exposure to secondhand smoke (SHS), is associated with adverse pregnancy outcomes including low birth weight (LBW) and small for gestational age infants due to the effect of tobacco on the anthropometric measurements of the newborn. This effect might be masked by maternal obesity as it increases fetal weight. The objectives of this study were to estimate the independent effects of maternal exposure to SHS and maternal body mass index (BMI) on the anthropometric measurements and on the prevalence of macrosomia and LBW among term infants.MethodsData were collected from women in the postnatal ward following delivery. Participants were stratified into six groups based on the BMI (underweight <18 kg/m2, non-obese 18–29.9 kg/m2, and obese ≥30 kg/m2) and the SHS exposure status (exposed and non- exposed), to examine the independent effects of BMI and SHS on infants’ anthropometry. Multiple regression analysis was used to explore the independent associations between the six groups and the risk of delivering a macrosomic or LBW infant.ResultsInfants of women exposed to SHS had significantly reduced anthropometric measurements compared to infants of unexposed women. The odds of delivering a macrosomic baby increased to 9-fold for women with BMI of ≥30 kg/m2 compared to non-obese women; odds ratio (OR) 9.18, 95% Confidence Interval (CI) (1.01, 9.37); p = 0.04, this risk was attenuated to 1.5-fold in women exposed to SHS, OR 1.53, 95% CI (1.19, 12.1); p < 0.0001. The odds of delivering an LBW infant were more than doubled in underweight women compared to non-obese women, OR 2.15, 95% CI (1.001, 4.57); p = 0.034, and were further increased to almost 3-fold for women who were exposed to SHS, OR 2.71, 95% CI (1.82,4.045); p = 0.02.ConclusionExposure to SHS was associated with reduced anthropometric measurements of the newborn and increased rate of LBW infants, irrespective of maternal BMI. Maternal obesity was associated with increased risk of delivering a macrosomic infant; conversely maternal underweight was associated with increased risk of delivering an LBW infant.

Association between secondhand smoke exposure and quality of life in pregnant women and postpartum women and the consequences on the newborns

“…SHS exposure is known to increase the risk of cardiovascular disease, lung cancer, and other respiratory diseases [30,31] in adult nonsmokers, and the effects of direct smoking by pregnant women have also been well documented [32]; our study shows that SHS exposure during pregnancy is associated with low birth weight and health problems in newborns consistent with the previous findings [33,34]. The effect of maternal SHS exposure prior to birth may carry forward to effects on adolescents’ body weight such as obesity [35].…”

Maternal and birth cohort studies in the Gulf Cooperation Council countries: a systematic review and meta-analysis

“…Fiftytwo (64.2%) cohort studies enrolled pregnant mothers at varying stages of their pregnancy with different characteristics such as diabetic and non-diabetic mothers [26,67], obesity [42,47,54], singleton [41,48,99] or triplet pregnancies [91], teenage women [112], multipara women [82,86,98], and women with systemic lupus erythematosus (SLE) [27]. Eight studies (9.9%) enrolled pregnant mothers at varying stages after delivery [24,49,58,59,81,84,88,99]. Seventeen studies (21.0%) recruited newborns at varying stages after birth [20,21,45,52,56,63,65,66,70,73,75,92,101,102,[105][106][107][108] such as preterm babies [20,66,73,105,108] (see Additional file 3: Table S2).…”

“…Environmental and anthropometric exposures were measured in only six (7.4%) and 16 (19.8%) of the 81 cohort studies, respectively. Environmental exposures included smoking and secondhand smoking [49,56], and all six studies on anthropometric measures were on BMI (Table 1 and see Additional file 3: Table S2). [47,50,53,54,83,111,113], and maternal anemia in three cohort studies [50,104,113].…”

“…Obese pregnant women in Saudi Arabia were 15% more likely to give birth to a macrosomic baby compared to non-obese women (pooled aRRs, 1.15; 95% CI, 1.00-1.25; I 2 = 50.0%) (Fig. 2) [47][48][49]. Following written communication with the study authors [48], we excluded two unverified point estimates due to the inaccuracy of the reported CI.…”

Independent and joint effects of prenatal maternal smoking and maternal exposure to second‐hand smoke on the development of adolescent obesity: A longitudinal study

“…23,30 It has been found that SHS is independently associated with reduced anthropometric measurements of the newborn and increased rate of low birthweight infants. 32 A cross-sectional study in the United States examining the impact of maternal and paternal smoking during pregnancy and the risk of overweight and obesity observed the strongest association with adult overweight and obesity when both parents smoked, although BMI was based on self-reported height and weight. 21 A prospective study in the Netherlands examined only the independent effect of maternal smoking during pregnancy and 'smoking in the parental house' on childhood overweight without assessing the joint effect of smoking and SHS exposure on the childhood overweight.…”