Does attrition affect estimates of association: A longitudinal study.

Survey research frequently involves missing cases attributable to refusals to participate, lack of success in accessing all potential respondents or loss to follow-up in longitudinal studies. There is concern that those not recruited or those lost are a select group whose absence from a study may bias the findings of the study. This study provides a test of the extent to which selective loss to follow-up in a longitudinal study may lead to biased findings. The Mater-University Study of Pregnancy collected baseline information for 7718 pregnant women. Follow-ups occurred five years, 14 years, 21 years and 27 years after the birth, for 6753 eligible women. Participants at baseline were partitioned according to follow-up status for each follow-up. We compare baseline (at recruitment) measures of association, with these same measures of association for those retained in the study (Group A) and those lost to follow-up (Group B) at each phase of data. Using univariate logistic regression we compared the strength of association between maternal mental health and various baseline socio-demographic factors for different rates of loss to follow-up. Estimates of association at baseline, and at each follow-up are similar irrespective of the rate of loss to follow-up and whether the comparison is with those retained in the study or those lost to follow-up. There were no statistically significant differences in 90.8% of baseline comparisons with Group A, and 96.9% of comparisons with Group B measures of association. We conclude that differential loss to follow-up rarely affects estimates of association. We suggest that loss to follow-up may produce misleading findings only in circumstances where loss to follow-up is combined with a number of other sources of bias.

Young adult pregnancy status and the risk of developing overweight and obesity among women and men.

Pregnancies can end in miscarriage, birth or termination. Although it is well known that pregnancy results in weight gain across the life course, it is unknown whether pregnancies which end in termination and miscarriage contribute to this. The study used a sub-sample of 3630 adult offspring from the original cohort of the Mater University of Queensland Study of Pregnancy (MUSP) and its outcomes, in Brisbane, Australia. Anthropometric data were measured at 5, 14 and 21 years of age and experience of pregnancy including termination, miscarriage and births were self-reported at 21 years. Multivariable analyses were conducted to determine whether pregnancy status of young people independently associated with overweight or obesity status. The women who had at least one birth were more likely to have overweight (odds ratio [OR] 1.52; 95% confidence interval [CI]: 1.01, 2.27) or obese (OR 2.38; 95% CI: 1.58, 3.59) compared to women who did not experience any pregnancy. Women whose pregnancies were terminated or miscarried were at the same risk of overweight or obesity as women who did not experience any pregnancy. For men, there is no association between the pregnancies in their partners and the mean difference in their body mass index. Young women whose pregnancies result in a birth, but not terminations or miscarriages, are at greater risk of having overweight or obesity following the birth.

Commonly occurring adverse birth outcomes and maternal depression: a longitudinal study.

OBJECTIVES: Little is known about whether commonly occurring adverse birth outcomes have a long-term impact on the mental health of mothers. The aim of this study was to investigate whether commonly occurring adverse birth outcomes predicted mothers' depressive-symptom trajectories over a 27-year period following the birth of a baby. STUDY DESIGN: Longitudinal study. METHODS: Participants comprised a sub-group of women from the longitudinal cohort of the Mater and University of Queensland Study of Pregnancy. Maternal depression was measured at six time points from the first clinic visit of an index pregnancy to 27 years after birth. A semi-parametric mixture model was used to identify three symptom trajectories of low-stable, moderate-stable and moderate-rising depression. Multinomial logistic regression was then used to determine whether a number of commonly occurring birth outcomes predicted moderate-stable and/or moderate-rising depression trajectories over the subsequent 27 years. Sociodemographic and behavioural factors were used to adjust for possible confounding. RESULTS: After adjustment for potential confounders, none of the adverse birth outcomes predicted subsequent maternal depression trajectories. Teenage pregnancy, not completing high school, low family income, obesity, poorer quality partnership and not exercising, measured at women's first clinic visit, and small social networks at three to five days after birth, were significantly associated with women's moderate-rising depressive-symptoms trajectory over 27 years. CONCLUSIONS: Commonly occurring adverse birth outcomes do not predict long-term depressive trajectories. A number of sociodemographic and behavioural factors present at the index pregnancy predict women's long-term pattern of depression throughout their reproductive life course.

The association between adolescent psychopathology and subsequent physical activity in young adulthood: a 21-year birth cohort study.

BACKGROUND: The beneficial effects of physical activity (PA) for both physical and mental wellbeing are well established. Given that adolescence presents a critical developmental period during which life-long patterns of PA become established, the exploration of the longitudinal impact of adolescent psychopathology on adult PA status is of interest. METHODS: We analysed prospective data from 3663 young adults who participated in the Mater-University of Queensland Study of Pregnancy. Psychopathology was measured using the Youth Self-Report (YSR) at age 14. Participants' engagement in three types of PA (vigorous exercise, moderate exercise and walking) at age 21 were dichotomised into either 'none' or 'any'. For our main analysis, we examined the association between the YSR score and subsequent PA engagement using logistic regression. We also conducted sensitivity analyses of longitudinal associations between the YSR internalising and externalising symptoms score at age 14 and PA engagement at age 21. RESULTS: We found no longitudinal association between the total YSR score at age 14 and PA engagement at age 21. In addition, there was no longitudinal association between the YSR internalising or externalising symptoms and PA engagement. CONCLUSION: Our findings suggest that there is no longitudinal association between adolescent psychopathology and PA in young adulthood.

Does having a difficult child lead to poor maternal mental health?

OBJECTIVES: Considerable evidence suggests maternal psychopathology influences that of their offspring. The probability of a reverse causal pathway has been only rarely considered but is a concern, given around 10% of children manifest mental impairment during their early years. This study determines the extent to which child behavior problems at ages 5 and 14 years are associated with mothers' mental health at 21 years post birth. STUDY DESIGN: Longitudinal study. METHODS: Data were taken from a sample of 3650 women from Mater and University of Queensland Study of Pregnancy birth cohort. Women's mental health was measured using the Mental Disorder Screening Tool at 21 years post birth. The Child Behavior Check List was used to measure internalizing, combined social/attention/thought disorder, and aggression at the age of 5 and 14 years. Logistic regression was used to derive odds ratios and 95% confidence intervals. A number of confounders were used to test for independence. RESULTS: Following all adjustments, child internalizing behaviors and combined social/attention/thought disorder at 5 years, and all measures of child behavior problem at 14 years were associated with mothers meeting criteria for mental health impairment at 21 years post birth. Moreover mothers of children with behavior problems at 14 years were approximately 2-3 times more likely to these meet these criteria. CONCLUSIONS: Mothers of children with behavior problems at 5 and 14 years of age were more likely to have mental health impairment at 21 years post birth. Child health professionals should be cognizant of the mother-child relationship having mutual mental health vulnerability.

Trajectories of maternal depression: a 27-year population-based prospective study.

AIMS: To identify distinct trajectories of depression experienced by a population-based sample of women over a 27-year period and to assess the validity of the derived trajectories. METHOD: The Mater University of Queensland Study of Pregnancy is a birth cohort study which commenced in 1981. Women (N = 6753) were interviewed at their first clinic visit, at 6 months, then 5, 14, 21 and 27 years after the birth of their child, using the Delusions Symptoms - States Inventory. Some 3561 (52.7%) women were followed up at 27 years, with 3337 (49.4%) of the sample completing the Composite International Diagnostic Interview (CIDI). Depression trajectories over a 27-year period were identified using Latent Class Growth Modelling (LCGM). LCGM was used to identify respondents with similar patterns of depression over a 27-year period. At the 27-year follow-up women who completed the CIDI, were stratified according to their trajectory group membership. RESULTS: Three trajectory groups, each with different life-course patterns of depression were identified. The low/no symptoms of depression trajectory group comprised 48.4% of women. The mid-depression group (41.7%) had a consistent pattern of occasional symptoms of depression. The high/escalating trajectory group comprised 9.9% of the women in the study. We then examined each trajectory group based on their completion of the CIDI at the 27-year follow-up. Using the CIDI, 27.0% of women in the study had met the DSM-IV criteria for lifetime ever depression by their mean age of 46.5 years. The responses to the CIDI differed greatly for each of the trajectory groups, suggesting that the trajectories validly reflect different life histories of depression. The high/escalating trajectory group had an earlier age of first onset, more frequent episodes, longer duration of each episode of depression and experienced higher levels of impairment for their episodes of depression. For the high symptoms trajectory group, clinically significant depression is estimated to be experienced by women almost one in every 6 days of their life. CONCLUSION: While symptoms of depression are commonly experienced in a large community-based sample of women, a minority of women experience many episodes of depression in their lifetime. It is this group of women who are most impaired and should be of most concern, and who should be the main target of prevention and treatment initiatives.

Generational increase in obesity among young women: a prospective analysis of mother-daughter dyads.

BACKGROUND/OBJECTIVES: Increases in obesity in young adults over recent decades are shown by national survey data but have yet to be replicated using prospective data. We aim to quantify the increase in obesity and overweight over two generations of young adult women using prospective measures of body mass index (BMI). SUBJECTS/METHODS: Data are from the Mater University Study of Pregnancy (MUSP), a prospective pre-birth cohort study started in 1981 in Brisbane, Australia. Analyses were restricted to 992 mother-daughter dyads who were at similar ages at the time they were assessed and for whom measures of BMI were available. We also conducted an additional analysis to test whether there was a similar increase amongst father-son dyads. We used multinomial logistic regression for clustered data to compare the same prospective measures of BMI categories between mother and daughters. RESULTS: Controlling for a number of sociodemographic and lifestyle factors in the female sample, daughters had 5.04 (3.03, 8.85) times the odds of being obese and 2.54 (1.86, 3.54) times the odds of being overweight compared with their mothers. A large increase in obesity was also observed in the male sample. CONCLUSIONS: Using a longitudinal design to partly account for familial confounding of obesity risk factors, this study confirms a large and concerning increases in obesity rates over two generations of young adults and suggests increases in obesity over the past 20 years may be greater than previously anticipated.

The heritability of delusional-like experiences.

OBJECTIVE: Delusional-like experiences (DLE) are common in the general community and are associated with a family history of mental illness. The aim of this study was to estimate the heritability of DLE. METHOD: The Peter's Delusional Inventory (PDI) was administered to a population-based cohort of mothers (n = 2861, aged 35-67 years) and their adult offspring (n = 3079, aged 18-23 years). Heritability of DLE was estimated from the sum scores of the 21 item PDI under the assumption that the covariance between mother-offspring scores is attributable to shared additive genetic factors. RESULTS: The means (medians and standard deviations) for the total PDI scores for the mothers and their offspring were 3.6 (3.0, 3.0) and 5.0 (4.0, 3.5), respectively. The Pearson correlation coefficient between mother and offspring PDI scores was 0.17 (P < 0.001). The heritability was estimated to be 0.35 (standard error 0.04). CONCLUSION: Heritable factors contribute to over a third of the variance of PDI scores in this population. In light of the association between a family history of a wide range of mental disorders and DLE, these experiences may represent a useful quantitative endophenotype for genetic studies of common mental disorders in population settings.

Smoking behaviour in pregnancy and its impact on smoking cessation at various intervals during follow-up over 21 years: a prospective cohort study.

OBJECTIVE: To determine whether mothers who quit or reduce their level of smoking in pregnancy comprise a group of health-conscious women who are disproportionally likely to adopt a healthier smoking lifestyle in the medium to longer term, compared with women who continue to smoke during pregnancy. DESIGN: A prospective cohort study. SETTING: A public hospital in Australia. POPULATION: A cohort of 6703 individual mothers who completed both initial phases of data collection in 1981-1983; mothers who smoked daily (2992) before pregnancy were included in this study. METHODS: Mothers were interviewed at 3-5 days post-delivery, 6 months, 5 years, 14 years and 21 years to determine their smoking status. An inverse probability-weighted Poisson regression with a robust error variance was fitted to the data using a log-link function and a binary response variable for smoking outcome, and adjusting for several possible confounding factors. MAIN OUTCOME MEASURE: Smoking cessation at several follow-up points, for up to 21 years. RESULTS: Of the mothers who smoked daily before pregnancy, 12, 23, 37 and 41% reported having ceased smoking at 6 months and at 5, 14 and 21 years, respectively. The decision to quit smoking during pregnancy was found to be independently associated with a higher rate ratio (RR) of smoking cessation at 6 months (RR 30.60, 95% CI 20.50-45.69), 5 years (RR 4.36; 95% CI 3.61-5.27), 14 years (RR 2.42, 95% CI 2.12-2.75) and 21 years (RR 1.86; 95% CI 1.60-2.15), after adjusting for several possible confounding factors. CONCLUSIONS: Pregnancy appears to be an opportunity for successfully quitting smoking, regardless of socio-economic circumstances or demographic background.

Does a history of hypertensive disorders of pregnancy help predict future essential hypertension? Findings from a prospective pregnancy cohort study.

Hypertensive disorder of pregnancy (HDP) is considered an important determinant in the prediction of future hypertension. The aim of this study is to examine whether HDP improves prediction of future hypertension, over prediction based on established risk factors measured during pregnancy. We used a community based cohort study of 2117 women who received antenatal care at a major hospital in Brisbane between 1981 and 1983 and had blood pressure assessed 21 years after the index pregnancy. Of these 2117 women, 193 (9.0%) experienced HDP and 345 (16.3%) had hypertension at 21 years postpartum. For women with HDP, the odds of being hypertensive at 21 years postpartum were 2.46 (95% CI 1.70, 3.56), adjusted for established risk factors including age, education, race, alcohol, cigarettes, exercise and body mass index. Addition of HDP did not improve the prediction model that included these established risk factors, with the area under the curve of receiver operator (AUROC) increasing from 0.710 to 0.716 (P-value for difference in AUROC=0.185). Our findings suggest that HDP is strongly and independently associated with future hypertension, and women who experience this condition should be counselled regarding lifestyle modification and careful ongoing blood pressure monitoring. However, the development of HDP during pregnancy does not improve our capacity to predict future hypertension, over risk factors identifiable at the time of pregnancy. This suggests that counseling regarding lifestyle modification and ongoing blood pressure monitoring might reasonably be provided to all pregnant and postpartum women with identifiable risk factors for future hypertension.

Adolescents bullying and young adults body mass index and obesity: a longitudinal study.

OBJECTIVE: To examine whether adolescent males and females who were victims of bullying were at greater risk of a higher body mass index (BMI) and obesity by young adulthood. DESIGN: Secondary analysis of data from a community-based cohort study. SUBJECTS: A sub-sample of 1694 offspring (50% males) who were participants in the Mater-University of Queensland Study of Pregnancy (MUSP), Brisbane, and who provided bullying information at 14 years and physical assessment at 21 years. MAIN OUTCOME MEASURES: BMI and its categories as normal, overweight or obese at 21 years. RESULTS: One in two adolescent males and one in three adolescent females reported that they had been bullied at school by others. We found that adolescent males and females who were bullied were at a significantly greater risk of a higher BMI and obesity by young adulthood. Fourteen-year-old males who were occasionally/often bullied at school had 0.64 (95% confidence interval (CI): 0.02, 1.27) kg m(2) greater mean BMI by 21 years compared with males who were never bullied by 14 years. This mean difference in BMI was 1.52, (95% CI: 0.75, 2.29) kg m(2) for females. Similarly, the odds of being obese were 2.54 (95% CI: 1.58, 4.09) times at 21 years for those males who were bullied occasionally/often compared with adolescent males who were never bullied. For females, this was 2.18 (95% CI: 1.40, 3.39). Overweight adolescents who experienced bullying had the greatest increase in BMI by young adulthood. Adjusting for potential confounding or mediating factors, the associations remain strong for males but are attenuated for females. CONCLUSIONS: The findings of this study suggest that both male and female adolescents who were bullied often/sometimes by their peer group at 14 years were at greater risk of higher BMI and obesity by young adulthood.

Family food behaviours and adolescents' overweight status: a mother-offspring link study.

BACKGROUND: The role of family food behaviours on weight status of family members is not well understood. The objective of this study was to examine the influence of some aspects of family food behaviours on adolescents overweight. METHOD: In a cross-sectional mother-child-linked study design, participants were a subsample of 3862 adolescents (51.9% boys) from the Mater hospital-University of Queensland Study of Pregnancy (MUSP), a longitudinal study of a birth cohort of 7,223 women and their offspring. Information on aspects of family food behaviours (family meal patterns and influences, frequency of family food consumption, and influences on family food selection) was collected by self reported questionnaires from mothers in a 14 years follow up (in 1994-1997) and other covariates at different stages of follow-ups. Body Mass Index of the adolescents was calculated using measured height and weight. RESULTS: Being overweight at 14 years had significant negative associations with mothers' report on the importance of family meals (OR=1.28), frequency of eating cake/biscuits (OR=1.71), and significant positive association with mothers' report on frequency of consumption of cooked vegetables (OR=1.32), soft drinks (OR=1.60) and importance of fattening of foods (OR=1.27). CONCLUSION: The study confirmed the importance of the family and some family food behaviours in shaping risk of being overweight amongst adolescents. Because of the cross-sectional nature of this study, we could not conclude that they had casual correlations. Comparison with the literature suggests that some of these effects may be specific to particular contexts, potentially affected by cultural and socio-economic differences.

Longitudinal correlates of the persistence of irregular eating from age 5 to 14 years.

AIM: To report the stability of parent-perceived child irregular eating from 6 months to 14 years of age and to investigate a predictive model inclusive of child and parent factors. METHODS: Of the 7223 singleton children in a birth cohort, 5122 children were re-interviewed at 5 years and 4554 for the 14-year analysis. Information was obtained from structured interviews including questions answered by parents of the child at birth, 6 months, 5 years and 14 years; and by teenagers at age 14 years and from physical measures of the child. The mother's perception that the child was an irregular eater at age 14 years was the major outcome variable of interest. RESULTS: Approximately 40% of irregular eaters at age 5 will still be irregular eaters at age 14 years. This was not related to maternal education or socio-economic class. Significant at multivariate analysis were infant feeding problems and the children's ability to regulate their sleep and mood. Significant maternal factors were greater age, not feeling positive about the baby and persistent maternal anxiety during the child's early years. CONCLUSION: Irregular eating behaviour displays considerable continuity from childhood to mid-adolescence. Independent contributions to this behavioural phenotype include child biological and psychological factors and maternal anxiety during the child's early years.

The antecedents of non-affective psychosis in a birth-cohort, with a focus on measures related to cognitive ability, attentional dysfunction and speech problems.

OBJECTIVE: Adults with non-affective psychosis show subtle deviations in a range of developmental trajectories as children and adolescents. METHOD: Based on a birth-cohort (n = 3801), we examined the Peabody Picture Vocabulary Test (PPTV) at age 5, and Raven's Standard Progressive Matrices (RSPM) and Wide Range Achievement Test reading scale (WRAT-R) at age 14. Items related to speech problems and attentional dysfunction were available from maternal- or self-report. At age 21, we identified 60 cohort members who were screen-positive for non-affective psychosis (SP-NAP). RESULTS: Impaired performance on the PPVT and RSPM (but not WRAT-R) predicted SP-NAP for males only. Male cohort members in the highest quartile for attentional dysfunction at ages 5 and 14 were about 5-8 times more likely to develop SP-NAP. SP-NAP in males was significantly associated with speech problems at age 14. CONCLUSION: Males who develop non-affective psychoses have subtle impairments in cognitive capacity prior to the development of their psychotic disorder.

Maternal smoking during and after pregnancy and lung function in early adulthood: a prospective study.

BACKGROUND AND AIMS: There is a paucity of evidence about whether exposure to antenatal smoking impacts on offspring's lung function in early adulthood. This study aimed to examine whether (1) in utero exposure to maternal smoking is related to poorer respiratory functioning in early adulthood; (2) the impact of prenatal smoking is independent of postnatal maternal smoking; and (3) the link between prenatal smoking and a young adult's lung function is explained by the child's birth weight, smoking or history of asthma. METHODS: Data were from a 21-year follow-up of mothers and their children recruited into the Mater-University of Queensland Study of Pregnancy, a longitudinal prebirth cohort. The study is based on 2409 young adults (1185 males and 1224 females) who had prospective data available on respiratory function at 21 years and maternal smoking during and after pregnancy. A Spirobank G spirometer system was used to measure forced vital capacity (FVC), forced expiratory volume in 1 s (FEV(1)) and forced expiratory flow between 25% and 75% of FVC (FEF(25-75)). RESULTS: In utero exposure to maternal smoking was associated with a reduction in FEV(1) and FEF(25-75) in males (regression coefficient, -0.16; 95% CI, -0.30 to -0.02), after accounting for maternal smoking after pregnancy. At least part of the effect of in utero smoking on young adults' lung function was explained by the child's birth weight and subsequent asthma. CONCLUSIONS: Adverse effects of antenatal smoking on development of airway growth may persist into early adulthood. Gender differences noted in this longitudinal cohort need to be explored further.

Predictors of maternal misclassifications of their offspring's weight status: a longitudinal study.

BACKGROUND: Very little is known about the factors influencing parental misclassifications of a child's weight status. The aim of this study is to examine the predictors of maternal misclassifications of their adolescent offspring's weight status. METHODS: A mother-child linked analysis was carried out using 14-year follow-up data from a population-based prospective birth cohort of 2650 children (52% males) who were participants in the Mater-University Study of Pregnancy in Brisbane (Australia) in 1981. Offspring's observed height and weight and maternal perception of offspring weight were reported when they were 14 years old and predictors were prospectively recorded either at first clinical visit of mothers or at 5 or 14 years follow-up. Maternal misclassifications were defined combining observed body mass index (BMI) categories and maternal perceptions of their offspring's weight status. RESULTS: We found that maternal misclassification of child's weight status was common and included misclassifications both to higher and lower weight categories. Forty percent of mothers of overweight children misclassified their child as normal or underweight, more so in males than females. Fifteen percent of mothers of normal weight children misclassified their child as underweight, again more so in males than females. The main independent predictors of maternal misclassifications of child weight status were gender, child dissatisfaction with appearance, shape, size and weight, dieting to lose weight, general health status, maternal BMI and family meals. Gender, child dissatisfaction, dieting and maternal overweight were especially associated with misclassifications of overweight children. CONCLUSIONS: This study identified a number of maternal, child and family factors associated with maternal misclassifications of child weight status. Although relevant for clinical practice, further study is needed, however, to evaluate the benefits and harms of promoting increasing parental and child awareness of the child's weight status at a population level.

Increasing body mass index from age 5 to 14 years predicts asthma among adolescents: evidence from a birth cohort study.

BACKGROUND: Obesity and asthma are common disorders, and the prevalence of both has increased in recent decades. It has been suggested that increases in the prevalence of obesity might in part explain the increase in asthma prevalence. This study aims to examine the prospective association between change in body mass index (BMI) z-score between ages 5 and 14 years and asthma symptoms at 14 years. METHODS: Data was taken from the Mater University Study of Pregnancy and its outcomes (MUSP), a birth cohort of 7223 mothers and children started in Brisbane (Australia) in 1981. BMI was measured at age 5 and 14 years. Asthma was assessed from maternal reports of symptoms at age 5 and 14 years. In this study analyses were conducted on 2911 participants who had information on BMI and asthma at both ages. RESULTS: BMI z-score at age 14 and the change in BMI z-score from age 5 to 14-years were positively associated with asthma symptoms at age 14 years, whereas BMI z-score at age 5 was not associated with asthma at age 14. Adjustment for a range of early-life exposures did not substantially alter these findings. The association between change in BMI z-score with asthma symptoms at 14 years appeared stronger for male subjects compared with female subjects but there was no statistical evidence for a sex difference (P=0.36). CONCLUSIONS: Increase in BMI z-score between age 5 and 14 years is associated with increased risk of asthma symptoms in adolescence.

Is being overweight associated with behavioural problems in childhood and adolescence? Findings from the Mater-University study of pregnancy and its outcomes.

AIMS: To examine the associations between being overweight and behavioural problems at ages 5 and 14. METHODS: Birth cohort study of 2875 individuals who were born in Brisbane between 1981 and 1984 and who were followed up at ages 5 and 14 years. Behavioural problems were defined as scoring above the 90th centile on Achenbach's child behavioural checklist. RESULTS: In cross-sectional analyses there was no association between being overweight and behavioural problems in either females at age 5. At age 14 females who were overweight were more likely than those who were normal weight to experience behavioural problems. However, there was no association between being overweight and behavioural problems at age 14 among males. The prevalence of behavioural problems increased linearly across the distribution of body mass index in females at age 14. In prospective analyses, among participants who had no behavioural problems at age 5, there was no association between being overweight at age 5 and behavioural problems at age 14 in either sex. Females who were overweight at age 5 and normal weight at age 14 had reduced odds of behavioural problems at age 14. CONCLUSIONS: Among adolescent females there is a positive linear association between body size and behavioural problems. However, no such association was found in adolescent males, or in either sex at age 5 years, and in prospective analyses being overweight at age 5 was not associated with behavioural problems in either sex at age 14.

Family and early life factors associated with changes in overweight status between ages 5 and 14 years: findings from the Mater University Study of Pregnancy and its outcomes.

OBJECTIVE: To describe different patterns of overweight status between ages 5 and 14 y and examine the role of modifiable family and early life characteristics in explaining different patterns of change between these two ages. DESIGN: A population-based prospective birth cohort. SUBJECTS: A total of 2934 children (52% males) who were participants in the Mater-University study of pregnancy, Brisbane, and who were examined at ages 5 and 14 y. MAIN OUTCOME MEASURES: Four patterns of change in overweight/obesity status between ages 5 and 14 y: (i) normal at both ages; (ii) normal at 5 y and overweight/obese at 14 y; (iii) overweight/obese at 5 y and normal at 14 y; (iv) overweight/obese at both ages. RESULTS: Of the 2934 participants, 2018 (68.8%) had a normal body mass index (BMI) at ages 5 and 14 y, 425 (14.5%) changed from a normal BMI at age 5 y to overweight or obese at age 14 y, 175 (6.0%) changed from being overweight or obese at age 5 y to normal weight at age 14 y and 316 (10.8%) were overweight or obese at both ages 5 and 14 y. Girls were more likely to make the transition from overweight or obese at age 5 y to normal at 14 y than their boy counterparts. Children whose parents were overweight or obese were more likely to change from having a normal BMI at age 5 y to being overweight at 14 y (fully adjusted RR: 6.17 (95% CI: 3.97, 9.59)) and were more likely to be overweight at both ages (7.44 (95% CI: 4.60, 12.02)). Birth weight and increase in weight over the first 6 months of life were both positively associated with being overweight at both ages. Other explanatory factors were not associated with the different overweight status transitions. CONCLUSIONS: Parental overweight status is an important determinant of whether a child is overweight at either stage or changes from being not overweight at 5 y to becoming so at 14 y.