Body Mass Index Growth Trajectories Research Articles

PM2.5 constituents associated with childhood obesity and larger BMI growth trajectory: A 14-year longitudinal study

BackgroundThe association of specific PM2.5 chemical constituents with childhood overweight or obesity (OWOB) remain unclear. Furthermore, the long-term impacts of PM2.5 exposure on the trajectory of children's body mass index (BMI) have not been explored. MethodsWe conducted a longitudinal study among 1,450,830 Chinese children aged 6–19 years from Beijing and Zhongshan in China during 2005–2018 to examine the associations of PM2.5 and its chemical constituents with incident OWOB risk. We extracted PM2.5 mass and five main component exposure from Tracking Air Pollution in China (TAP) dataset. Cox proportional hazards models were applied to quantify exposure–response associations. We further performed principal component analysis (PCA) to handle the multi-collinearity and used quantile g-computation (QGC) approach to analyze the impacts of exposure mixtures. Additionally, we selected 125,863 children with at least 8 physical examination measurements and combined group-based trajectory models (GBTM) with multinomial logistic regression models to explore the impacts of exposure to PM2.5 mass and five constituents on BMI and BMI Z-score trajectories during 6–19 years. ResultsWe observed each interquartile range increment in PM2.5 exposure was significantly associated with a 5.1 % increase in the risk of incident OWOB (95 % confidence Interval [CI]: 1.036–1.066). We also found black carbon, sulfate, organic matter, often linked to fossil combustion, had comparable or larger estimates of the effect (HR = 1.139–1.153) than PM2.5. Furthermore, Exposure to PM2.5 mass, sulfate, nitrate, ammonium, organic matter and black carbon was significantly associated with an increased odds of being in a larger BMI trajectory and being assigned to persistent OWOB trajectory. ConclusionsOur findings provide evidence that the constituents mainly from fossil fuel combustion may have a perceptible influence on increased OWOB risk associated with PM2.5 exposure in China. Moreover, long-term exposure to PM2.5 contributes to an increased odds of being in a lager BMI and a persistent OWOB trajectories.

Associations of prenatal exposure to bisphenols with BMI growth trajectories in offspring within the first two years: evidence from a birth cohort study in China.

Prenatal bisphenol exposure has been reported to be associated with lower birth weight and obesity-related indicators in early childhood. These findings warrant an investigation of the relationship between prenatal bisphenol exposure and the dynamic growth of offspring. This study aimed to evaluate the relationship of maternal bisphenol concentration in urine with the body mass index (BMI) growth trajectory of children aged up to twoyears and to identify the critical exposure periods. A total of 826 mother-offspring pairs were recruited from Wuhan Children's Hospital between November 2013 and March 2015. Maternal urine samples collected during the first, second, and third trimesters were analyzed for bisphenol A (BPA), bisphenol S, and bisphenol F (BPF) concentrations. Measurements of length and weight were taken at 0, 1, 3, 6, 8, 12, 18, and 24months. Children's BMI was standardized using the World Health Organization reference, and group-based trajectory modeling was used to identify BMI growth trajectories. The associations between prenatal bisphenol exposure and BMI growth trajectory patterns were assessed using multinomial logistic regression models. The BMI growth trajectories of the 826 children were categorized into four patterns: low-stable (n = 134, 16.2%), low-increasing (n = 142, 17.2%), moderate-stable (n = 350, 42.4%), and moderate-increasing (n = 200, 24.2%). After adjusting for potential confounders, we observed that prenatal exposure to BPA during the second trimester [odds ratio (OR) = 2.20, 95% confidence interval (CI) = 1.09-4.43] and BPF during the third trimester (OR = 3.28, 95% CI = 1.55-6.95) at the highest quartile concentration were associated with an increased likelihood of the low-increasing BMI trajectory. Furthermore, in the subgroup analysis by infant sex, the positive association between the highest quartile of prenatal average urinary BPF concentration during the whole pregnancy and the low-increasing BMI trajectory was found only in girls (OR = 2.82, 95% CI = 1.04-7.68). Our study findings suggest that prenatal exposure to BPA and BPF (a commonly used substitute for BPA) is associated with BMI growth trajectories in offspring during the first twoyears, increasing the likelihood of the low-increasing pattern. Video Abstract (MP4 120033kb).

Prenatal Exposure to Multiple Endocrine-Disrupting Chemicals and Childhood BMI Trajectories in the INMA Cohort Study.

Prenatal exposure to endocrine-disrupting chemicals (EDCs) may disrupt normal fetal and postnatal growth. Studies have mainly focused on individual aspects of growth at specific time points using single chemical exposure models. However, humans are exposed to multiple EDCs simultaneously, and growth is a dynamic process. The objective of this study was to evaluate the associations between prenatal exposure to EDCs and children's body mass index (BMI) growth trajectories using single exposure and mixture modeling approaches. Using data from the INfancia y Medio Ambiente (INMA) Spanish birth cohort (), prenatal exposure to persistent chemicals [hexachlorobenzene (HCB), 4-4'-dichlorodiphenyldichloroethylene (DDE), polychlorinated biphenyls (PCB-138, -150, and -180), 4 perfluoroalkyl substances (PFAS)] and nonpersistent chemicals (8 phthalate metabolites, 7 phenols) was assessed using blood and spot urine concentrations. BMI growth trajectories were calculated from birth to 9 years of age using latent class growth analysis. Multinomial regression was used to assess associations for single exposures, and Bayesian weighted quantile sum (BWQS) regression was used to evaluate the EDC mixture's association with child growth trajectories. In single exposure models exposure to HCB, DDE, PCBs, and perfluorononanoic acid (PFNA) were associated with increased risk of belonging to a trajectory of lower birth size followed by accelerated BMI gain by 19%-32%, compared with a trajectory of average birth size and subsequent slower BMI gain [e.g., relative risk ratio (RRR) per doubling in DDE (95% CI: 1.05, 1.35); RRR for (95% CI: 1.05, 1.66)]. HCB and DDE exposure were also associated with higher probability of belonging to a trajectory of higher birth size and accelerated BMI gain. Results from the BWQS regression showed the mixture was positively associated with increased odds of belonging to a BMI trajectory of lower birth size and accelerated BMI gain (odds ratio per 1-quantile increase of the ; credible interval: 1.03, 2.61), with HCB, DDE, and PCBs contributing the most. This study provides evidence that prenatal EDC exposure, particularly persistent EDCs, may lead to BMI trajectories in childhood characterized by accelerated BMI gain. Given that accelerated growth is linked to a higher disease risk in later life, continued research is important. https://doi.org/10.1289/EHP11103.

BMI growth trajectory from birth to 5 years and its sex-specific association with prepregnant BMI and gestational weight gain.

The purpose of the study was to identify the latent body mass index (BMI) z-score trajectories of children from birth to 5 years of age and evaluate their sex-specific association with prepregnant BMI and gestational weight gain (GWG). This was a retrospective longitudinal cohort study performed in China. In total, three distinct BMI-z trajectories from birth to 5 years of age were determined for both genders using the latent class growth modeling. The logistic regression model was used to assess the associations of maternal prepregnant BMI and GWG with childhood BMI-z growth trajectories. Excessive GWG increased the risks of children falling into high-BMI-z trajectory relative to adequate GWG (OR = 2.04, 95% CI: 1.29, 3.20) in boys; girls born to mothers with prepregnancy underweight had a higher risk of low-BMI-z trajectory than girls born to mothers with prepregnancy adequate weight (OR = 1.85, 95% CI: 1.22, 2.79). BMI-z growth trajectories of children from 0 to 5 years of age have population heterogeneity. Prepregnant BMI and GWG are associated with child BMI-z trajectories. It is necessary to monitor weight status before and during pregnancy to promote maternal and child health.

Early-life stress and current stress predict BMI and height growth trajectories in puberty.

In cross-sectional analyses, early institutional care is associated with shorter stature but not obesity during puberty in children adopted into US families. We examined whether shorter stature and leaner body composition in youth adopted internationally from institutions would continue as puberty progressed. We also examined whether current psychosocial stress would moderate the association between early institutional deprivation and growth during adolescence. Using an accelerated longitudinal design and linear mixed-effects models, we examined the height and body mass index (BMI) of 132 previously institutionalized (PI) and 176 nonadopted (NA) youth. We examined youth aged 7-15 at the beginning of the study three times across 2 years. Nurses assessed anthropometrics and pubertal status. Current psychosocial stress was measured using the Youth Life Stress Interview. Our results indicated that PI youth remained shorter and leaner across three assessments than NA youth. However, age-and-sex-adjusted BMI increased faster in PI youth. Psychosocial stress during puberty predicted greater age-and-sex-adjusted BMI, but this effect did not differ by group. The gap in BMI but not height appears to close between PI and NA youth. Higher psychosocial stress was associated with higher BMI during puberty.

Association Between Trajectory Patterns of Body Mass Index Change Up to 10 Months and Early Gut Microbiota in Preterm Infants.

Recent research suggests that gut microbiota plays an important role in the occurrence and development of excessive weight and obesity, and the early-life gut microbiota may be correlated with weight gain and later growth. However, the association between neonatal gut microbiota, particularly in preterm infants, and excessive weight and obesity remains unclear. To evaluate the relationship between gut microbiota and body mass index (BMI) growth trajectories in preterm infants, we examined microbial composition by performing 16S rDNA gene sequencing on the fecal samples from 75 preterm infants within 3 months after birth who were hospitalized in the neonatal intensive care unit of Hunan Children’s Hospital from August 1, 2018 to October 31, 2019. Then, we collected their physical growth information during 0–10 months. Latent growth mixture models were used to estimate growth trajectories of infantile BMI, and the relationship between the gut microbiota and the BMI growth trajectories was analyzed. The results demonstrated that there were 63,305 and 61 operational taxonomic units in the higher BMI group (n = 18), the lower BMI group (n = 51), and the BMI catch-up group (n = 6), respectively. There were significant differences in the abundance of the gut microbiota, but no significant differences in the diversity of it between the lower and the higher BMI group. The BMI growth trajectories could not be clearly distinguished because principal component analysis showed that gut microbiota composition among these three groups was similar. The three groups were dominated by Firmicutes and Proteobacteria in gut microbiota composition, and the abundance of Lactobacillus in the higher BMI group was significantly different from the lower BMI group. Further intervention experiments and dynamic monitoring are needed to determine the causal relationship between gut microbiota differences and the BMI change.

Maternal vitamin D status in relation to infant BMI growth trajectories up to 2years of age in two prospective pregnancy cohorts.

BackgroundEarly childhood growth can affect the child's health status later in life. Maternal vitamin D status has been suggested to affect early childhood growth. However, there is a lack of studies investigating the role of maternal vitamin D status on growth trajectories during infancy. By using growth mixture modeling (GMM), maternal vitamin D status during pregnancy can be investigated in relation to different classes of infant growth trajectories.ObjectivesTo examine the association between maternal 25‐hydroxyvitamin D (25OHD) and classes of infant body mass index (BMI) growth trajectories.MethodsMother–child pairs were included from the Norwegian Mother, Father, and Child Cohort Study (MoBa, n = 2522) and the Swedish GraviD cohort (n = 862). Maternal 25OHD in pregnancy was analyzed by liquid chromatography tandem mass spectrometry. Children's weights and heights were registry‐based. GMM identified classes of infant BMI growth trajectories up to 2 years. The association between maternal 25OHD and infant BMI class by cohort was estimated using a log‐link generalized linear model. Mixed model analysis estimated the pooled association including both cohorts.ResultsTwo infant BMI classes were identified, stable normal and stable high. In MoBa, maternal 25OHD <50 and 50–75 nmol/L were associated (RR 2.70, 95% CI 1.26–5.77 and RR 2.56, 95% CI 1.20–5.47) with a higher risk of the infant stable high BMI class, compared with 25OHD >75 nmol/L. In GraviD, no association was found. In pooled analysis, maternal 25OHD ≤75 nmol/L was non‐significantly associated with a higher risk of the stable high BMI growth class.ConclusionsMaternal 25OHD ≤75 nmol/L may be associated with a higher class of BMI growth trajectory during infancy.

Low length/weight growth trajectories of early-term infants during the first year: evidence from a longitudinal study in China

ObjectiveTo identify common length, weight and body mass index (BMI) growth trajectories of term infants during infancy, and to determine their association with early-term infants.DesignProspective longitudinal study.SettingWuhan, China.PatientsA total of...

Socioeconomic disparities and infancy growth trajectory: a population-based and longitudinal study

BackgroundThe association of low socioeconomic status (SES) with childhood and adolescent obesity has been reported. It is unknown whether low SES affects body mass index (BMI) growth trajectory in the first 12 mo of life. Moreover, accelerated growth as a compensatory mechanism for low birth weight (LBW) during infancy, is an important predictor of later obesity. The aim of the present study was to examine the association of low SES with infancy BMI growth rate and trajectory for LBW and normal birth weight (NBW) infants.MethodsFrom September 2012 to October 2014, a total of 387 infants in this longitudinal study was subjected to repeated measures of weight and length from birth to 12 mo in Hefei. Generalized growth mixture modeling was used to classify the infancy BMI growth trajectories. Differences in infancy BMI z score (zBMI) and BMI growth rate between low SES and high SES were estimated based on linear regression after adjusting for several confounders including maternal age, pregnancy BMI, physical activity during pregnancy, paternal BMI as well as alcohol use, paternal smoking status, breastfeeding duration and delivery mode.ResultsInfancy BMI trajectories in this study were classified into three categories: rapid growth (class 1), normal growth (class 2) and slow growth (class 3). Low SES infants had the higher zBMI than high SES infants for LBW group at age 6 mo [zBMI difference with 95% CI at 6 mo: 0.28(0.03, 0.53); at 12 mo: 0.21(0.01, 0.43)]. Low SES infants had more rapid zBMI growth rate than those with high SES for low birth weight between 0 and 6 months. Controlling for the confounders, these associations remained robust. We found the lower SES in the rapid growth group.ConclusionsThese findings highlighted the impact of low SES on increasing BMI and accelerated growth during early infancy. Health care and relatively optimal family environment in the first 12 mo of life, especially for LBW infants, are benefit to shape the better infancy growth trajectory.

Birth cohort study on the effects of complementary feeding on body mass index growth trajectories from birth to 24 months in rural Western China

Birth cohort study on the effects of complementary feeding on body mass index growth trajectories from birth to 24 months in rural Western China

Hypothalamic-pituitary-adrenal axis attenuation and obesity risk in sexually abused females

BackgroundChildhood sexual abuse (CSA) confers elevated risks for obesity in females. Mechanisms that explain this link remain unclear. This study tracked serum basal cortisol levels with body mass index (BMI) from childhood into adulthood to test whether hypothalamic-pituitary-adrenal (HPA) axis attenuation accounts for elevated obesity risks for sexually abused females. MethodsData drew from six timepoints of a longitudinal study of the impact of CSA on development. Participants were females aged 6–16 years at time of study enrollment with substantiated CSA and demographically matched non-abused peers. Analyses included only participants who did not have obesity at study enrollment. Main outcomes were BMI growth trajectories across ages 6–27 (n = 150; 66 abused, 84 comparisons) and early adulthood obesity status (ages 20–27; n = 133; 62 abused, 71 comparison). HPA axis functioning indicators were intercept and linear slope parameters extracted from multilevel growth trajectories of serum basal cortisol levels across development. Racial-ethnic minority status, parity, steroid medication use, depression history and disordered eating history were covaried. ResultsWhile controlling for covariates, multilevel modeling indicated that high initial serum basal cortisol levels in childhood and attenuated cortisol growth rate over time (i.e., HPA axis attenuation) were associated with accelerated BMI accumulation (p < .01). Attenuated cortisol growth rate mediated the effect of CSA on accelerated BMI accumulation and on elevated adulthood obesity rates (p < .05). ConclusionThis work establishes a mechanistic association between HPA axis attenuation and obesity, suggesting that trauma treatments for abuse survivors should include interventions that reduce health consequences associated with dysregulated stress physiology.

Adolescent Tri-ponderal Mass Index Growth Trajectories and Incident Diabetes Mellitus in Early Adulthood.

Studies have reported the influence of adolescent obesity on development of adult diabetes, but the effect of the growth pattern during this period has rarely been explored. Also, the tri-ponderal mass index (TMI) was thought to be a better estimation of adolescent body fat levels than the body mass index (BMI), so we sought to investigate whether growth trajectories derived by these two indices could predict incident diabetes. We conducted a study by using the Taipei City Hospital Radiation Building Database, a longitudinal cohort established in 1996. Physical exam results including blood test results were collected annually and the BMI z-score/TMI growth trajectory groups during 13 to 18 years of age were identified using growth mixture modeling. A Cox proportional hazard model for incident diabetes was used to examine the risk of baseline obese status and different BMI/TMI growth trajectories. Five growth trajectory groups were identified for the BMI z-score and the TMI. During approximately 20 400 person-years follow-up, 33 of 1387 participants developed diabetes. Baseline obesity defined by the BMI z-score and the TMI were both related to adult diabetes. The persistent increase TMI growth trajectory exhibited a significantly increased risk of diabetes after adjusting for baseline obese status and other correlated covariates (hazard ratio: 2.85, 95% confidence interval: 1.01-8.09). There was no association between BMI growth trajectory groups and incident diabetes. A specific TMI growth trajectory pattern during adolescence might be critical for diabetes prevention efforts.

Maternal seafood intake during pregnancy, prenatal mercury exposure and child body mass index trajectories up to 8 years.

BackgroundMaternal seafood intake during pregnancy and prenatal mercury exposure may influence children’s growth trajectories.MethodsThis study, based on the Norwegian Mother, Father and Child Cohort Study (MoBa), includes 51 952 mother-child pairs recruited in pregnancy during 2002–08 and a subsample (n = 2277) with maternal mercury concentrations in whole blood. Individual growth trajectories were computed by modelling based on child’s reported weight and length/height from 1 month to 8 years. We used linear mixed-effects regression analysis and also conducted discordant-sibling analysis.ResultsMaternal lean fish was the main contributor to total seafood intake in pregnancy and was positively but weakly associated with child body mass index (BMI) growth trajectory. Higher prenatal mercury exposure (top decile) was associated with a reduction in child’s weight growth trajectory, with the estimates ranging from -130 g [95% Confidence Intervals (CI) = -247, -12 g] at 18 months to -608 g (95% CI = -1.102, -113 g) at 8 years. Maternal fatty fish consumption was positively associated with child weight and BMI growth trajectory, but only in the higher mercury-exposed children (P-interaction = 0.045). Other seafood consumption during pregnancy was negatively associated with child weight growth compared with no intake, and this association was stronger for higher mercury-exposed children (P-interaction = 0.004). No association was observed between discordant maternal seafood intake and child growth in the sibling analysis.ConclusionsWithin a population with moderate seafood consumption and low mercury exposure, we found that maternal seafood consumption in pregnancy was associated with child growth trajectories, and the direction of the association varied by seafood type and level of prenatal mercury exposure. Prenatal mercury exposure was negatively associated with child growth. Our findings on maternal seafood intake are likely non-causal.

Early life exposure to air pollution, green spaces and built environment, and body mass index growth trajectories during the first 5 years of life: A large longitudinal study

Urban environments are characterized by multiple exposures that may influence body mass index (BMI) growth in early life. Previous studies are few, with inconsistent results and no evaluation of simultaneous exposures. Thus, this study aimed to assess the associations between exposure to air pollution, green spaces and built environment characteristics, and BMI growth trajectories from 0 to 5 years. This longitudinal study used data from an electronic primary care health record database in Catalonia (Spain), including 79,992 children born between January 01, 2011 and December 31, 2012 in urban areas and followed until 5 years of age. Height and weight were measured frequently during childhood and BMI (kg/m2) was calculated. Urban exposures were estimated at census tract level and included: air pollution (nitrogen dioxide (NO2), particulate matter <10 μm (PM10) and <2.5 μm (PM2.5)), green spaces (Normalized Difference Vegetation Index (NDVI) and % green space) and built environment (population density, street connectivity, land use mix, walkability index). Individual BMI trajectories were estimated using linear spline multilevel models with several knot points. In single exposure models, NO2, PM10, PM2.5, and population density were associated with small increases in BMI growth (e.g. β per IQR PM10 increase = 0.023 kg/m2, 95%CI: 0.013, 0.033), and NDVI, % of green spaces and land use mix with small reductions in BMI growth (e.g. β per IQR % green spaces increase = −0.015 kg/m2, 95%CI: −0.026, −0.005). These associations were strongest during the first two months of life. In multiple exposure models, most associations were attenuated, with only those for PM10 and land use mix remaining statistically significant. This large longitudinal study suggests that early life exposure to air pollution, green space and built environment characteristics may be associated with small changes in BMI growth trajectories during the first years of life, and that it is important to account for multiple exposures in urban settings.

Grandparents' wealth and the body mass index trajectories of grandchildren.

The aims of this study are to (i) examine associations between grandparents' wealth and grandchild's initial body mass index (BMI) in early childhood and its subsequent growth patterns, and to (ii) assess whether the associations are similar for white and black children. Data are from the U.S. Panel Study of Income Dynamics (PSID) and its supplemental studies of Child Development Supplement (CDS) and Transition to Adulthood (TA) (N = 2,128). Three-level growth curve models are used to analyze the association between exposure to grandparental wealth in early childhood and grandchildren's BMI growth trajectories, accounting for parental sociodemographic characteristics and maternal BMI levels. Children with less grandparental wealth in early childhood have higher initial BMI than children with more grandparental wealth. Further, increases in grandparental wealth in childhood are associated with a slower BMI growth rate. The wealth-body mass index associations are more evident among white children than black children. The study reveals a multigenerational social gradient to body mass index. Elevating the wealth levels of the grandparent generation could potentially reduce their grandchildren's obesity risk. The protective role of grandparental wealth seems to be more evident among white families than black families.

Body mass index growth trajectories, early pubertal maturation, and short stature.

Childhood body mass index (BMI) trajectory classes are rarely linked to early puberty risk, particularly among Chinese children. We estimated early puberty risk across BMI trajectory classes, investigated factors contributing to pubertal development, and examined differences in final adult height between children exhibiting early and nonearly pubertal maturation across the classes. The Taiwan Children Health Study recruited 10-year-old children in 2010 from 14 Taiwanese communities and resurveyed them at age 11, 12, and 18 years. The study comprised 3109 children (50.4% boys) with available data for BMI (age 6-11 years) and pubertal stages (age 11, 12, and 18 years). Classes 1-4 were persistently healthy weight, rapid BMI growth, chronically overweight/obese, and early transient overweight/obese. Children in class 3 exhibited the highest risk of early pubertal maturation. Puberty genetic score, low sleep quality, and high fat-free mass collectively explained 15% of the variance in Tanner stages among class 3 children. Early pubertal maturation was considered to cause short and tall stature in boys and girls, respectively. Modifying sleep quality and fat-free mass may reduce early puberty risk in children with chronic overweight/obesity. Vigorous physical activity may reduce adiposity and increase the final adult height in the children.

Non-Food Behavioral Regulation at Age 4 Predicts Body Mass Index Growth Trajectory Membership

Non-Food Behavioral Regulation at Age 4 Predicts Body Mass Index Growth Trajectory Membership

Multilevel analysis of BMI growth trajectories of US school children: Features and risk factors.

Childhood obesity continues to be a major focus of public health efforts in the United States, where nearly 17% of children are obese. In this study, we focused on two significant features that characterize U.S. society—school mobility and a single-parent family structure—and how they relate to childhood obesity/overweight. Using a nationally representative sample from the Early Childhood Longitudinal Study—Kindergarten (ECLS-K) class of 1998, we examined the body mass index (BMI) growth trajectories of children to determine how these two key features interacted with demographic characteristics of gender, race/ethnicity, and socio-economic status (SES), which are known to be associated with BMI. We analyzed five waves of data from kindergarten through fifth grade of 9041 students applying a two-level hierarchical linear model (HLM). Results indicated that children who changed schools more than two times from kindergarten to fifth grade had higher BMI growth trajectories compared to children who changed only once or did not change schools. To our knowledge, no prior studies have examined this association. Results also indicated children in single-parent families were more likely to have higher BMI growth trajectories compared to children in two-parent families. Although both school mobility and family structure had an impact on children's BMI, we found that family structure had a larger impact than school mobility. Being in a two-parent family was a protective factor for children; that is, even if children in two-parent families moved schools twice or more, they still maintained a healthy BMI on average. For children in single-parent families, however, moving schools tended to have a greater, negative impact on their BMI statuses.

Rate of change in body mass index at different ages during childhood and adult obesity risk.

Childhood body mass index (BMI) predicts adult obesity. How growth trajectories during childhood relate to adult obesity risk is not well defined. We aimed to characterize BMI growth trajectories from childhood to midlife and to examine the associations between BMI growth rates at childhood age points and adult obesity risk. The longitudinal study included 2732 participants with repeated BMI measurements from childhood (4-19y) to adulthood (20-51y). A random-effects model was used to construct BMI growth curves by race and sex. Model-estimated levels and linear growth rates of BMI were linked to adult obesity in separate multivariable logistic regression models at individual childhood age points. BMI followed cubic growth curves. Childhood BMI linear slope estimates were higher in adults with obesity than in adults without obesity (P<0.001). The association between childhood BMI growth rate and adult obesity was significantly higher in puberty and postpuberty (12-19y) than in early childhood (4-11y) with a peak at age 14 (odds ratio=3.1 and 95% confidence interval, 2.7-3.5). Rates of change in BMI at different childhood ages are differentially associated with adult obesity. Puberty and postpuberty are crucial periods for the development of obesity in later life.

Fetal exposure to maternal active and secondhand smoking with offspring early-life growth in the Healthy Start study.

Previous studies have modeled the association between fetal exposure to tobacco smoke and body mass index (BMI) growth trajectories, but not the timing of catch-up growth. Research on fetal exposure to maternal secondhand smoking is limited. To explore the associations between fetal exposure to maternal active and secondhand smoking with body composition at birth and BMI growth trajectories through age 3 years. We followed 630 mother-child pairs enrolled in the Healthy Start cohort through age 3 years. Maternal urinary cotinine was measured at ~ 27 weeks gestation. Neonatal body composition was measured using air displacement plethysmography. Child weight and length/height were abstracted from medical records. Linear regression models examined the association between cotinine categories (no exposure, secondhand smoke, active smoking) with weight, fat mass, fat-free mass, and percent fat mass at birth. A mixed-effects regression model estimated the association between cotinine categories and BMI. Compared to unexposed offspring, birth weight was significantly lower among offspring born to active smokers (-343-g; 95% CI: -473, -213), but not among offspring of women exposed to secondhand smoke (-47-g; 95% CI: -130, 36). There was no significant difference in the rate of BMI growth over time between offspring of active and secondhand smokers (p = 0.58). Therefore, our final model included a single growth rate parameter for the combined exposure groups of active and secondhand smokers. The rate of BMI growth for the combined exposed group was significantly more rapid (0.27 kg/m2 per year; 95% CI: 0.05, 0.69; p < 0.01) than the unexposed. Offspring prenatally exposed to maternal active or secondhand smoking experience rapid and similar BMI growth in the first three years of life. Given the long-term consequences of rapid weight gain in early childhood, it is important to encourage pregnant women to quit smoking and limit their exposure to secondhand smoke.