Leah Li

Intergenerational influences on childhood body mass index: the effect of parental body mass index trajectories

BACKGROUNDnParental obesity in adulthood is a strong determinant of offspring obesity. Whether parental body mass index (BMI; in kg/m2) at earlier life stages is associated with offspring BMI is unknown.nnnOBJECTIVEnThe main objective was to assess whether recent BMI of parents in adulthood and their recent BMI gain are more strongly associated with offspring BMI than are BMI or changes in parental BMI in childhood.nnnDESIGNnTwo generations in the 1958 British birth cohort were studied, including cohort members (parents generation) with BMI at 7, 11, 16, 23, and 33 y (n = 16,794) and a one-third sample of their offspring selected in 1991 aged 4-18 y (n = 2908). We applied multilevel models to allow for within-family correlations.nnnRESULTSnChildhood BMI increased on average by 0.25-1.10 between the 2 generations, depending on sex and age group, and overweight/obesity increased from 10% to 16%. Parents BMI in childhood and adulthood independently influenced offspring BMI, but no significant difference in the strength of influence was observed. For example, adjusted increase in BMI for offspring aged 4-8 y was equivalent to 0.37 and 0.23 for a 1-SD increase in maternal BMI at 7 and 33 y, respectively. Similar patterns were observed for risk of overweight/obesity and for paternal BMI at most ages.nnnCONCLUSIONSnExcessive BMI gains of parents during childhood and adulthood were associated with a higher BMI and risk of obesity in the offspring. Reductions in the incidence of child obesity in the current population may reduce obesity in future generations.

Is childcare associated with the risk of overweight and obesity in the early years? Findings from the UK Millennium Cohort Study

Background:A recent assessment of childcare in OECD (Organisation for Economic Co-operation and Development) countries highlighted the potential for childcare to widen inequalities. Although childcare offers a potential setting for obesity prevention, little research has analysed the association between childcare and overweight, particularly in different socio-economic groups.Objectives:Our primary objective was to explore the association between childcare and overweight (including obesity), both overall and by socio-economic background, in a contemporary UK cohort of children at age 3 years (N=12u2009354). Our secondary objective was to explore infant feeding as a potential mediator between childcare in infancy and overweight at age 3 years.Results:After controlling for confounders, children who were cared for in informal childcare (75% grandparents) between the age of 9 months and 3 years were more likely to be overweight than those cared for only by a parent (adjusted risk ratio (aRR)=1.15, 95% confidence interval (CI) 1.04–1.27), particularly if they were in full-time childcare (aRR=1.34, 95% CI 1.15–1.57). When stratifying by socio-economic background, the increased risk of overweight in informal childcare (compared with parental care) was limited to children from more advantaged groups: those whose mother was from a managerial or professional background (aRR=1.23, 95% CI 1.02–1.47), had a degree (RR=1.43, 95% CI 1.13–1.83) or lived in a couple household (RR=1.18, 95% CI 1.06–1.32). There was no association between formal childcare and overweight. Infant feeding did not mediate the association between childcare use in infancy and overweight at age 3 years.Conclusions:Children from more advantaged families who use informal childcare are at increased risk of overweight. The UK governments drive to support parents into paid employment should be accompanied by health-related information and support for both informal and formal carers. As the majority of informal carers were grandparents, the recent government announcement to provide grandparents with National Insurance credits for caring for grandchildren provides a potential opportunity for health promotion.

Predicting cardiovascular disease risk factors in midadulthood from childhood body mass index: utility of different cutoffs for childhood body mass index

BACKGROUNDnIdentifying adults at increased risk of cardiovascular disease (CVD) on the basis of childhood body mass index (BMI) could be informative for disease prevention but depends on the utility of childhood BMI cutoffs.nnnOBJECTIVEnWe aimed to establish how well the International Obesity Task Force (IOTF) and population-specific cutoffs for childhood BMI predict CVD risk factors in midadulthood.nnnDESIGNnWe used the 1958 British birth cohort, whose BMI measures were collected at 7, 11, and 16 y and whose CVD risk factors (obesity, hypertension, adverse lipid concentrations, and type 2 diabetes risk) were collected at 45 y. The sensitivity and specificity of IOTF and population-specific cutoffs for childhood BMI were calculated for each CVD risk factor.nnnRESULTSnThe prevalence of overweight or obesity was low in childhood (<11%, IOTF cutoffs) compared with that in adulthood (75% men, 56% women). The IOTF cutoffs had high specificities (91.6-97.9%) but low sensitivities (7.1-31.5%) for predicting adult outcomes. In comparison, population-specific cutoffs identified large groups of children (eg, >38% for predicting adult obesity) who had improved sensitivities (17.3-67.3%) but lower specificities (52.9-84.6%) compared with IOTF cutoffs. Accelerated BMI gains in childhood predicted adult obesity and type 2 diabetes risk, but prediction was no greater than that for childhood BMI at one age (area under the curve: 0.55-0.65 compared with 0.59-0.75). Childhood BMI and BMI gain were weak predictors of adult hypertension and adverse lipid concentrations.nnnCONCLUSIONnNeither the IOTF cutoffs nor our population-specific cutoffs for childhood BMI are adequate diagnostic tools for adult CVD risk factors in a population experiencing rapid changes in obesity prevalence over their lifetime.

Childhood Maltreatment and BMI Trajectories to Mid-Adult Life: Follow-Up to Age 50y in a British Birth Cohort

Background Childhood maltreatment including abuse and neglect has been associated with adult obesity, but evidence on life-course development of obesity or BMI gain is unclear. We aim to establish whether childhood maltreatments are related to obesity or BMI at different life-stages 7y-50y and to identify possible explanations for associations. Methods Childhood physical, psychological and sexual abuse, neglect and BMI at seven ages were recorded in the 1958 birth cohort (n~15,000). Associations of child maltreatments with BMI at separate ages were tested using linear regression or logistic regression for obesity, and with rate of child-to-adult BMI gain using multilevel models. We adjusted for potential covariates. Results Abuse was reported in ~12% of the population. Abuse was not associated with elevated childhood BMI, but adult associations were observed: i.e. the abused had faster child-adult BMI gain than the non-abused; associations were independent of adult covariates. For physical abuse in both genders there was a positive linear association of ~0.006/y zBMI gain with age after adjustment for all covariates. Similarly, there was a linear association of physical abuse with obesity risk: e.g. among females from a low ORadjusted of 0.34 (0.16,0.71) at 7y to 1.67 (1.25,2.24) at 50y. In females faster zBMI gains with age of ~0.0034/y were observed for sexual abuse and increases in obesity risk were faster: from a low ORadjusted of 0.23 (0.06,0.84) at 7y to 1.34 (0.86,2.10) at 50y. Psychological abuse and neglect associations were less consistent. Conclusions Childhood maltreatment associations with BMI or obesity varied across life: physical and, in females, sexual abuse were associated with faster lifetime BMI gains, which may have detrimental long-term health consequences.

Physical (in)activity over 20 y in adulthood: Associations with adult lipid levels in the 1958 British birth cohort

OBJECTIVESnTo investigate associations between physical (in)activity at different life-stages and lipids in mid-adulthood, examining the role of potential confounding and mediating factors, such as adiposity.nnnMETHODSnData from the 1958 British birth cohort (n=7824) were examined. Using linear regression, we analysed prospectively reported frequency of activity and TV-viewing (23, 33, 42 and 45 y) in relation to total, LDL-, HDL-cholesterol and triglycerides, at 45 y.nnnRESULTSnActivity at different ages was associated with HDL-cholesterol and triglycerides at 45 y: e.g. in men, a 1 day/week greater activity frequency at 42 y was associated with 0.006 mmol/L higher HDL-cholesterol and 1.4% lower triglycerides. Most associations attenuated, but were not entirely explained by adjustment for covariates (life-styles and socio-economic factors): e.g. among men, the estimated 2.0% lower triglycerides per 1 day/week greater frequency at 33 y reduced to 1.8% after adjustment. Among women, though not men, activity at both 23 and 45 y contributed cumulatively to HDL-cholesterol. For sedentary behaviour, associations were found for sitting at work: a 1 h/day greater sitting among men was associated with a 0.012 mmol/L lower HDL-cholesterol after adjustment for covariates. Associations were seen for TV-viewing: e.g. in men, a 0.04 mmol/L lower HDL-cholesterol and 5.9% higher triglycerides per hour/day greater TV-viewing at 45 y, attenuated, respectively, to 0.03 mmol/L and 4.6% after adjustment for covariates. Associations attenuated further after adjustment for current BMI. Associations for total and LDL-cholesterol were less consistent.nnnCONCLUSIONnActivity and sedentary behaviour at different adult ages were associated with HDL-cholesterol and triglycerides in mid-adulthood. Associations were partly mediated by other life-style factors and by BMI.

Psychological health throughout life and adult cortisol patterns at age 45 y.

Population-based studies of cortisol and psychological health over long periods are rare. This study aims to establish whether cortisol levels in mid-adulthood are associated with chronicity and life-stage of psychological ill-health onset. We used data from the 1958 British birth cohort (3209 males; 3315 females) with cortisol measures 45 min post-waking (t1) and 3h later (t2) on the same day at 45y. Lifetime psychological health was identified from child and adult measures (ages 7, 11, 16, 23, 33, 42, 45y). t1 cortisol was lower by 3-4% in those with lifetime (child and adult) ill-health than those with no ill-health, after adjustment for socio-economic position and smoking. t1 cortisol was similarly lowered in those with adult onset of ill-health, but not among the group whose ill-health was of recent onset. t2 cortisol was elevated among all lifetime ill-health groups, by 6-9%, except for those whose ill-health did not extend beyond childhood. Simple analyses across the separate ages of follow-up suggest that elevations in t2 cortisol reflect associations for adult ill-health. Our study suggests that psychological ill-health over years and decades blunts post-awakening cortisol secretion, possibly reflecting HPA dysregulation due to social stressors.

Child maltreatment and household dysfunction: associations with pubertal development in a British birth cohort

BACKGROUNDnWe aimed to establish the association between adverse childhood experiences (maltreatment and household dysfunction) and pubertal maturation, which is associated with later health outcome(s).nnnMETHODSnThe 1958 British birth cohort (n = 17 638) includes all born in one week, March 1958, followed up to mid adulthood. Pubertal stage was rated by medical personnel at 11 and 16 years of age (y). Childhood maltreatment (neglect or abuse) and household dysfunction scores were constructed from information ascertained in childhood and at 45 y.nnnRESULTSnChildhood neglect, assessed at 7 y, was associated with late pubertal development on several markers after adjusting for early life circumstances: relative risk ratio (RRRadjusted) was 1.13 (95% CI: 1.06,1.21) and 1.06 (1.00,1.12) for late menarche and breast development (females) per unit increase in neglect score ranging 0-7, respectively; 1.14 (1.08,1.20) for late voice change and 1.07 (1.02,1.13) for pubic hair growth (males). The RRRadjusted for late pubic hair (females) and genitalia and facial hair (males) development was 1.04 (P = 0.052 to 0.085). Abuse score (0-3, for physical, sexual or psychological abuse) was associated in females with late menarche [RRRadjusted = 1.17 (1.01,1.36)] and in males with late pubic hair growth [RRRadjusted = 1.16 (1.01,1.34)] per unit increase, but not with other pubertal markers. Neither score (neglect or abuse) was associated with early puberty, but sexual abuse was associated with early [RRRadjusted = 1.86 (1.06,3.29)] as well as late menarche [RRRadjusted = 1.66 (1.02,2.71)] and witnessing abuse with early genitalia development [RRRadjusted = 1.57 (1.02,2.41)]. Household dysfunction score was not associated consistently with pubertal markers.nnnCONCLUSIONSnCumulative neglect by 7 y was associated with delayed development of several pubertal markers. The underlying role of pubertal development in linking childhood neglect with future adult health warrants further consideration.

Trends in resting pulse rates in 9–11-year-old children in the UK 1980–2008

Objective Little is known about whether levels of physical fitness, which is related to adiposity and physical activity (PA), have changed in children, particularly the progressive increase in childhood obesity levels. We aimed to examine the time trends in resting pulse rate (a marker of physical fitness) among UK children, in order to better understand the trends in levels of physical fitness in recent decades. Design and setting We used a cross-sectional study design and included data on over 22u2005000 children aged 9–11u2005years (mean 10.3u2005years) from five population-based studies conducted in the UK between 1980 and 2008. Main outcome measures Resting pulse rate (bpm). Results Observed mean resting pulse rate was higher for girls than boys (82.2u2005bpm vs 78.7u2005bpm). During the study period mean pulse rate increased by 0.07u2005bpm/year (95% CI 0.04 to 0.09) among boys and to a lesser extent among girls, by 0.04u2005bpm/year (0.01 to 0.06) (p<0.05 for gender interaction). For boys, there was an indication that the trend was steeper after the mid-1990s, compared to that prior to 1994 (annual increase 0.14 vs 0.04u2005bpm). The trends for Body Mass Index (BMI) accounted for only 13.8% (11.3% to 16.3%) of increase in pulse rate for boys and 17.2% (9.4% to 24.9%) for girls. Conclusions Increases in mean resting pulse rate have occurred during the period 1980–2008 in girls and especially in boys. The increase was not explained by increased BMI. The observed trends in children, though modest, could have important public health implications for future cardiovascular risk.

Childcare use and inequalities in breastfeeding: findings from the UK Millennium Cohort Study

Background UK breastfeeding rates are low and socially distributed. Childcare provides a potential setting for breastfeeding promotion. However, little is known about the association between childcare and breastfeeding in different socio-economic groups. Methods Using data from a contemporary UK cohort of infants (n=18 050) the authors calculated RR for breastfeeding for at least 4 months according to informal childcare (care by friends, grandparents, other relatives, etc) and formal childcare (eg, nurseries, crèches), both lasting at least 10 h a week and commencing before the age of 4 months, compared to being cared for ‘only by a parent’ (this includes childcare for less than 10 h a week), overall and by socio-economic group. Results Compared to being looked after only by a parent, informal (RR 0.51 (95% CI 0.43 to 0.59)) and formal (0.84 (0.72 to 0.99)) childcare was associated with a reduced likelihood of breastfeeding. For informal childcare, both part-time and full-time care was associated with a reduced risk of breastfeeding, whereas for formal care, only full-time formal childcare was associated with a reduced likelihood of breastfeeding. The reduced likelihood of breastfeeding in informal childcare was similar across all socio-economic groups, whereas for formal childcare the reduced likelihood was only seen for mothers from managerial and professional backgrounds (0.76 (0.62 to 0.94)), those who had a degree (0.71 (0.58 to 0.86)) and couple families (0.79 (0.66 to 0.94)). In contrast, lone mothers were more likely to breastfeed if their infant was cared for in formal childcare (1.65 (1.04 to 2.63)). Conclusions Informal childcare was associated with a reduced likelihood of breastfeeding for all groups of mothers. Formal childcare arrangements were only associated with a reduced likelihood of breastfeeding if used full-time by more advantaged families.

Adverse childhood experiences and child-to-adult height trajectories in the 1958 British birth cohort

BACKGROUNDnAdverse childhood experiences (maltreatment and household dysfunction) are associated with adult cardiovascular disease (CVD). One possible pathway is through physical development, which has been linked to CVD risk. Our aim was to examine whether adverse childhood experiences are associated with child-to-adult height trajectories.nnnMETHODnThe 1958 British birth cohort (n=17,638) includes all born in one week in March 1958, followed up to mid adulthood. Height was measured at 7, 11 and 16 years (y) and adulthood (converted to standard deviation scores (SDS); ≥1 height measurement n=16,444, adult leg length n=9180). Multivariate response models were used to examine the associations between childhood experiences (ascertained at 7 y and self-reported at 45 y) and child-to-adult height.nnnRESULTSnChildhood neglect, prospectively assessed at 7 y, was associated with shorter stature throughout childhood: for each increment across a score ranging 0-7, average height reduced by 0.06 SDS (males) and 0.05 SDS (females) at 7 y (≈0.3 cm), with smaller deficits (0.03 SDS, ≈0.2 cm) in adulthood, after adjustment for parental height, birthweight and socio-economic factors. In males, the adult deficit was mainly due to shorter leg length. Household dysfunction was associated with shorter stature at 7-11 y, with adjusted deficits from 0.04 to 0.07 SDS per increment across a score ranging 0-7, but not at later ages. Adjusted models showed no associations for retrospectively reported abuse or neglect to 16 y.nnnCONCLUSIONSnThose with a higher neglect score by 7 y grew more slowly, with deficits through to adulthood. No associations were found for abuse over the longer period to 16 y. Deficits associated with early life neglect and household dysfunction might have implications for adult CVD risks.