The impact of maternal prenatal smoking on the development of childhood overweight in school-aged children

Maternal smoking during pregnancy and offspring body mass index and overweight: a systematic review and meta-analysis

Abstract: The present study aimed to conduct a systematic review and meta-analysis to evaluate the evidence on the association of maternal smoking during pregnancy with offspring body composition in childhood, adolescence and adulthood. MEDLINE, Web of Science and LILACS databases were searched. Reference lists were also screened. We included original studies, conducted in humans, that assessed the association of maternal smoking during pregnancy with offspring body mass index (BMI) and overweight in childhood, adolescence and adulthood, published through May 1st, 2018. A meta-analysis was used to estimate pooled effect sizes. The systematic review included 64 studies, of which 37 evaluated the association of maternal smoking during pregnancy with overweight, 13 with BMI, and 14 evaluated both outcomes. Of these 64 studies, 95 measures of effect were extracted and included in the meta-analysis. We verified that the quality of evidence across studies regarding maternal smoking in pregnancy and overweight and BMI of offspring to be moderate and low, respectively. Most studies (44 studies) were classified as moderate risk bias. Heterogeneity among studies included was high and, in the random-effects pooled analysis, maternal smoking during pregnancy increased the odds of offspring overweight (OR: 1.43, 95%CI: 1.35; 1.52) and mean difference of BMI (β: 0.31, 95%CI: 0.23; 0.39). In conclusion, offspring of mothers who smoked during pregnancy have higher odds of overweight and mean difference of BMI, and these associations persisted into adulthood.

Predictors of Severe Obesity in Low-Income, Predominantly Hispanic/Latino Children: The Texas Childhood Obesity Research Demonstration Study

INTRODUCTION

The objective of this study was to identify predictors of severe obesity in a low-income, predominantly Hispanic/Latino sample of children in Texas.

METHODS

This cross-sectional analysis examined baseline data on 517 children from the secondary prevention component of the Texas Childhood Obesity Research Demonstration (TX CORD) study; data were collected from September 2012 through February 2014. Self-administered surveys were used to collect data from parents of children who were aged 2 to 12 years, had a body mass index (BMI) in the 85th percentile or higher, and resided in Austin, Texas, or Houston, Texas. Multivariable logistic regression models adjusted for sociodemographic covariates were used to examine associations of children's early-life and maternal factors (large-for-gestational-age, exclusive breastfeeding for ≥4 months, maternal severe obesity [BMI ≥35.0 kg/m2]) and children's behavioral factors (fruit and vegetable consumption, physical activity, screen time) with severe obesity (BMI ≥120% of 95th percentile), by age group (2-5 y, 6-8 y, and 9-12 y).

RESULTS

Across all ages, 184 (35.6%) children had severe obesity. Among children aged 9 to 12 years, large-for-gestational-age at birth (odds ratio [OR] = 2.31; 95% confidence interval [CI], 1.13-4.73) was significantly associated with severe obesity. Maternal severe obesity was significantly associated with severe obesity among children aged 2 to 5 years (OR = 2.67; 95% CI, 1.10-6.47) and 9 to 12 years (OR = 4.12; 95% CI, 1.84-9.23). No significant association was observed between behavioral factors and severe obesity in any age group.

CONCLUSION

In this low-income, predominantly Hispanic/Latino sample of children, large-for-gestational-age and maternal severe obesity were risk factors for severe obesity among children in certain age groups. Promoting healthy lifestyle practices during preconception and prenatal periods could be an important intervention strategy for addressing childhood obesity.

Maternal smoking and risk of obesity in school children: Investigating early life theory from the GRECO study

Based on the Early Life Theory, maternal smoking may be a factor affecting child weight status, adiposity level and blood pressure later in life. The purpose of this study was primarily to examine the risk of maternal smoking during pregnancy with overweight and obesity, central and total adiposity in school children. Secondarily, to assess the effect of maternal smoking, with children's blood pressure (BP). Data from the Greek Childhood Obesity cross sectional study (GRECO), conducted from October 2008 to May 2009, were used. A total of 2400 questionnaires gathered from children and their parents were analysed. Maternal and gestational data were gathered by a self-administered questionnaire. Women were categorized as non-smokers or smokers if they smoked ≥ 1 cigarettes/day during pregnancy. Children's body weight, height, waist circumference and BP were measured. Multiple logistic and linear regression analysis was conducted, adjusting for covariates. Four models were used in the process. The study found that children of maternal-smokers were more likely to be overweight or obese (OR: 1.6 to 1.82) and to have a larger waist circumference (OR: 1.73 to 1.85), compared to children of non-smokers in all models used. Total fat percentage was not significantly associated with maternal smoking when adjusted. Systolic and diastolic BP was not associated with maternal smoking. Results of this study strengthen the need for smoking cessation during pregnancy in order to possibly reduce the childhood obesity epidemic. Creating public health awareness of the potential risk of maternal-smoking on children's weight status later in life is warranted.

Breastfeeding Reduces Childhood Obesity Risks

BACKGROUND

The present study examined the effects of breastfeeding and its duration on the development of childhood obesity from 24 months through grade 6.

METHODS

U.S. longitudinal data collected from 1234 children were analyzed using logistic regression models and generalized estimating equation (GEE). Child height and weight were measured six times at ages of 24 months, 36 months, 54 months, grade 1, grade 3, and grade 6.

RESULTS

During the early 1990s, prevalence of breastfeeding was low in the United States, 60% and 48% at 1 and 6 months, respectively. Nonsmoking, white, married mothers with both parents in the household, and with income above the poverty line, were more likely to breastfeed at 1 month of age of their babies. Obesity rate of the children increased with age from 24 months to grade 6. Logistic regression showed that breastfeeding at month 1 was associated with 53% (odds ratio [OR]: 0.47, 95% confidence interval [CI]: 0.30-0.73) and 47% (OR: 0.53, 95% CI: 0.36-0.78) decreased risks for childhood obesity at grades 1 and 6, respectively. GEE analysis showed that breastfeeding at 1 month reduced risk for childhood obesity by 36% (95% CI: 0.47-0.88) from ages 24 months through grade 6. Regarding breastfeeding duration, more than 6 months (vs. never) was associated with a decreased risk for childhood obesity by 42% (OR: 0.58, 95% CI: 0.36-0.94).

CONCLUSIONS

Breastfeeding at 1 month and more than 6 months reduced the risk of childhood obesity. Rate of breastfeeding was low in the United States in the 1990s, which may have had long-term implications on children.

Does intrauterine tobacco exposure increase the pain perception of newborns?

Background

This study aimed to assess whether there was a difference in the pain-perception levels of newborns born to mothers who smoked during pregnancy and newborns born to mothers who were not exposed to active or passive smoking during pregnancy.

Materials and methods

A total of 60 newborns born by normal spontaneous vaginal birth between June 2013 and June 2014 were included in the study: 30 born to mothers who smoked during pregnancy, and 30 born to mothers not exposed to smoking. Mothers or newborns who had taken analgesics or sedative medications in the previous 24 hours, newborns not born at term, and sick newborns were not included in the study. During the routine hepatitis B-vaccination injection given at postnatal 48 hours, the newborns’ behavior was monitored and recorded by video camera. The data obtained from the recordings were evaluated according to the Neonatal Pain, Agitation, and Sedation Scale and analyzed with SPSS 20.

Results

The median pain score of the group exposed to tobacco smoke in utero was 8.5, while the median pain score of the unexposed group was 6 (P<0.001).

Conclusion

Exposure to tobacco smoke in utero may increase the pain-perception levels of newborns.

Metabolic effects of smoking cessation

Smoking continues to be the leading cause of preventable death in the USA, despite the vast and widely publicized knowledge about the negative health effects of tobacco smoking. Data show that smoking cessation is often accompanied by weight gain and an improvement in insulin sensitivity over time. However, paradoxically, post-cessation-related obesity might contribute to insulin resistance. Furthermore, post-cessation weight gain is reportedly the number one reason why smokers, especially women, fail to initiate smoking cessation or relapse after initiating smoking cessation. In this Review, we discuss the metabolic effects of stopping smoking and highlight future considerations for smoking cessation programs and therapies to be designed with an emphasis on reducing post-cessation weight gain.

Association of early and late maternal smoking during pregnancy with offspring body mass index at 4 to 5 years of age

The objective was to investigate the association between early and late maternal smoking during pregnancy on offspring body mass index (BMI). We undertook a retrospective cohort study using linked records from the Women’s and Children’s Health Network in South Australia. Among a cohort of women delivering a singleton, live-born infants between January 2000 and December 2005 (n=7658), 5961 reported not smoking during pregnancy, 297 reported quitting smoking during the first trimester of pregnancy, and 1400 reported continued smoking throughout pregnancy. Trained nurses measured the height and weight of the children at preschool visits in a state-wide surveillance programme. The main outcome measure was age- and sex-specific BMI z-score. At 4 to 5 years, mean (s.d.) BMI z-score was 0.40 (1.05), 0.60 (1.07) and 0.65 (1.18) in children of mothers who reported never smoking, quitting smoking and continued smoking during pregnancy, respectively. Compared with the group of non-smokers, both quitting smoking and continued smoking were associated with an increase in child BMI z-score of 0.15 (95% confidence interval: 0.01–0.29) and 0.21 (0.13–0.29), respectively. A significant dose–response relationship was also observed between the number of cigarettes smoked per day on average during the second half of pregnancy and the increase in offspring BMI z-score (P<0.001). In conclusion, any maternal smoking in pregnancy, even if mothers quit, is associated with an increase in offspring BMI at 4 to 5 years of age.

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

AIM

To examine associations of prenatal maternal smoking and second-hand smoke (SHS) exposure with the development of adolescent obesity.

METHODS

Longitudinal data (1991-2007) from National Institute of Child Health and Human Development Study of Early Child Care and Youth Development involving mothers that smoked and or exposed to SHS during the year before birth were analysed. Adolescent obesity in ages 12.0-15.9 years was defined as a BMI ≥ 95th percentile. Generalised estimating equations (GEE) were used for the analyses.

RESULTS

Obesity was more prevalent among adolescents whose mothers smoked or had SHS exposure than those that did not smoke or exposed to SHS. After adjusting for maternal and child factors, GEE models showed that odds of adolescent obesity increased with prenatal maternal smoking (OR = 1.57, 95% CI = 1.03-2.39) and SHS exposure (OR = 1.53, 95% CI = 1.04-2.27). The odds for obesity increased more than two times among adolescents exposed to both maternal smoking and SHS (OR = 2.10, 95% CI = 1.24, 3.56) compared with those without exposure. Additionally, not breastfeeding, maternal obesity, and longer screen viewing hours per day were associated with increased odds of obesity.

CONCLUSIONS

There is possibly a long-term joint effect of prenatal maternal smoke (smoking and SHS) exposure on obesity among adolescent offspring, and the effect is independent of birthweight. These findings suggest that adolescent obesity could possibly be curtailed with the development and promotion of smoking cessation programmes for families during the year before birth.

Persistent effects of maternal smoking during pregnancy on lung function and asthma in adolescents

RATIONALE

The extent to which maternal smoking in pregnancy (MSP) has persisting effects on respiratory health remains uncertain and the mechanisms involved are not fully understood. Alterations in immune function have been proposed as a mechanism contributing to respiratory disease.

OBJECTIVES

To determine whether MSP increases risk of respiratory disorders in adolescence and, if so, whether this occurs by decreased lung function, altered immune function, and/or enhanced atopy.

METHODS

Data on spirometry, bronchial responsiveness, respiratory symptoms, total and allergen-specific IgE and IgG4, immune function, and inflammatory markers were obtained from 1,129 participants in the 14-year follow-up of the Western Australian Pregnancy (Raine) Cohort and related to MSP using regression analyses.

MEASUREMENTS AND MAIN RESULTS

MSP was reported for 21.0% (237 of 1,129) of participants, with 92 (8.1%) reporting current smoking. MSP was associated with some altered immune measures at age 14. MSP was strongly related to reduced lung function in current nonsmokers (forced expiratory flow midexpiratory phase [FEF25-75%], P = 0.016; FEV1/FVC, P = 0.009) and increased risk for current asthma (odds ratio [OR], 1.84; 95% confidence interval [CI], 1.16-2.92; P = 0.01), current wheeze (OR, 1.77; 95% CI, 1.14-2.75; P = 0.011), and exercise-induced wheeze (OR, 2.29; 95% CI, 1.37-3.85; P = 0.002), but not for bronchial hyperresponsiveness or atopy. Adjustment for immune measures and/or lung function in multivariate models did not greatly alter these associations and the increased risks for asthma and wheeze were not modified by sex, atopy, or maternal history of asthma or atopy.

CONCLUSIONS

MSP increases risk of asthma and wheezing in adolescence; mechanisms go beyond reducing lung function and exclude altering immune function or enhancing atopy.

Socioeconomic status, infant feeding practices and early childhood obesity

BACKGROUND

Children from low socioeconomic households are at greater risk of obesity. As breastfeeding can protect against child obesity, disadvantaged infants are less likely to breastfeed relative to more advantaged children. Whether infant feeding patterns, as well as other maternal characteristics mediate the association between social class and obesity has not been established in available research.

OBJECTIVES

Examine the impact of infant feeding practices on child obesity and identify the mechanisms that link socioeconomic status (SES) with child obesity.

METHODS

Based on a nationally representative longitudinal survey (ECLS-B) of early childhood (n = 8030), we examine how breastfeeding practices, the early introduction of solid foods and putting an infant to bed with a bottle mediate the relationship between social class and early childhood obesity relative to the mediating influence of other maternal characteristics (BMI, age at birth, smoking, depression and daycare use).

RESULTS

Infants predominantly fed formula for the first 6 months were about 2.5 times more likely to be obese at 24 months of age relative to infants predominantly fed breast milk. The early introduction of solid foods (< 4 months) and putting the child to bed with a bottle also increased the likelihood of obesity. Unhealthy infant feeding practices were the primary mechanism mediating the relationship between SES and early childhood obesity. Results are consistent across measures of child obesity although the effect size of infant feeding practices varies.

CONCLUSIONS

The encouragement and support of breastfeeding and other healthy feeding practices are especially important for low socioeconomic children who are at increased risk of early childhood obesity. Targeting socioeconomically disadvantaged mothers for breastfeeding support and for infant-led feeding strategies may reduce the negative association between SES and child obesity. The implications are discussed in terms of policy and practice.