Breastfeeding and adolescent blood pressure: evidence from Hong Kong's "Children of 1997" Birth Cohort

Breastfeeding Duration and Cardiometabolic Health during Adolescence: A Longitudinal Analysis

OBJECTIVE

To investigate the longitudinal association between breastfeeding duration and cardiometabolic health, using repeated measures study design among children and adolescents.

STUDY DESIGN

This study included 634 offsprings aged 10 to 21 years (52% female) from the Early Life Exposure in Mexico to Environmental Toxicants birth cohort followed up to four time points during adolescence. Breastfeeding duration was prospectively quantified using questionnaires during early childhood. Cardiometabolic risk factors, body composition, and weight-related biomarkers were assessed as outcomes during adolescent follow-up visits. Sex-stratified linear mixed-effects models were used to model the association between quartiles of breastfeeding duration and outcomes, adjusting for age and additional covariates.

RESULTS

Median breastfeeding duration was 7 months (minimum = 0, maximum = 36). Boys in the second quartile (median breastfeeding = 5 months) had lower total fat mass % (β (SE) -3.2 (1.5) P = .037), and higher lean mass % (3.1 (1.6) P = .049) and skeletal muscle mass % (1.8 (0.8) P = .031) compared with the reference group (median breastfeeding = 2 months). A positive linear trend between breastfeeding duration and trunk lean mass % (0.1 (0.04) P = .035) was found among girls. No association was found with other cardiometabolic indicators.

CONCLUSION

Despite sex-specific associations of breastfeeding duration with body composition, there was a lack of substantial evidence for the protective effects of breastfeeding against impaired cardiometabolic health during adolescence among Mexican youth. Further longitudinal studies with a robust assessment of breastfeeding are recommended.

Breastfeeding is associated with reduced risks of central obesity and hypertension in young school-aged children: a large, population-based study

BACKGROUND

Previous studies examined the effects of breastfeeding on measured values of body circumferences or blood pressure during childhood. However, limited data are available for the association between child feeding and a specific disease diagnosed as central obesity or hypertension. Hence, we aimed to examine whether the type and duration of breastfeeding are associated with obesity/central obesity or hypertension in young school-aged children.

METHODS

We matched the data obtained from a cross-sectional survey in 2019 with retrospective breastfeeding information recorded in the database. Heights, weights, waist circumferences, and blood pressures of 8480 children in first grade of primary schools in Shanghai, China were measured to diagnose obesity, central obesity, and hypertension. Data on child feeding was collected retrospectively from clinical records. Associations between the type/duration of breastfeeding and children's measured values of body mass index, waist circumference, and blood pressure were analysed by linear regression. Associations between the type/duration of breastfeeding and risks of obesity, central obesity, and hypertension were analysed by generalised linear models.

RESULTS

Breastfeeding duration was inversely associated with blood pressure values in children in the first grade. Each month's increase in the duration of any breastfeeding was associated with a 0.07 mmHg decrease in systolic blood pressure (P < 0.01) and a 0.05 mmHg decrease in diastolic blood pressure (P < 0.01). Any breastfeeding > one month was associated with a reduced risk of hypertension (adjusted risk ratio 0.84; 95% CI 0.73, 0.96, P = 0.01). Exclusive breastfeeding > one month was associated with a reduced risk of central obesity (adjusted risk ratio 0.76; 95% CI: 0.60, 0.96, P = 0.02). Any breastfeeding > 12 months was linked with a lower risk of hypertension (adjusted risk ratio 0.83; 95% CI 0.70, 0.98, P = 0.03).

CONCLUSIONS

Lack of breastfeeding is associated with higher risks of central obesity and hypertension during middle childhood. As a potential component of the public health strategy to reduce population levels of metabolic and cardiovascular diseases, breastfeeding could be a vital prevention strategy.

Breastfeeding and ApoB in late adolescence: a Hong Kong birth cohort study

Breastfeeding is widely promoted. Experimental evidence concerning long-term benefits is limited. Observational studies are open to bias from confounding by socio-economic position. We assessed the association of breastfeeding with late adolescent lipid sub-fractions, particularly apolipoprotein B (ApoB) and non-high-density lipoprotein cholesterol (non-HDL-c), overall and by sex. We took advantage of a setting where breastfeeding has little association with higher socio-economic position and where several results from randomized controlled trials of breastfeeding promotion have been replicated. We used the population-representative "Children of 1997" birth cohort comprising 88% of births in Hong Kong in April and May 1997. Associations of breastfeeding in the first 3 months of life (never, mixed, exclusive) with lipid sub-fractions were obtained using linear regression adjusted for potential confounders including parental socio-economic position, maternal place of birth, type of delivery, gestational age, and birth weight. Differences by sex were assessed. Multiple imputation and inverse probability weighting were used to recover the original sample. Of the 3462 participants included, mean age was 17.6 years and 48.8% were girls. Mean ApoB was 0.74 g/L (standard deviation 0.15). Exclusive versus never breastfeeding was associated with lower ApoB (-0.027 g/L, 95% confidence interval (CI)-0.046 to-0.007, p = 0.007) and lower non-HDL-c (-0.143 mmol/L, 95% CI-0.237 to-0.048) with similar estimates by sex.

CONCLUSION

Breastfeeding may provide some population-level lifelong protection against cardiovascular disease. This study supports policies promoting breastfeeding as a modifiable exposure that contributes to a healthy start in life as an investment for lifelong cardiovascular disease prevention.

WHAT IS KNOWN

• Apolipoprotein B (ApoB) is a recognized risk factor for cardiovascular disease, but whether breastfeeding affects ApoB in later life overall and by sex is unknown.

WHAT IS NEW

• Exclusive breastfeeding in the first 3 months of life was associated with lower ApoB in late adolescence, with similar estimates for both sexes. • The inverse association of breastfeeding with ApoB suggests that breastfeeding could reduce cardiovascular disease and overall mortality over the lifespan.

Breastfeeding Duration and High Blood Pressure in Children and Adolescents: Results from a Cross-Sectional Study of Seven Provinces in China

This study was aimed to investigate the associations between breastfeeding duration and blood pressure (BP) levels, BP Z scores and high BP (HBP) in children and adolescents. A total of 57,201 participants including 29,491 boys and 27,710 girls aged 7−18 years were recruited from seven provinces in China in 2012. HBP was defined as BP levels of ≥95th percentiles of the referent age-, sex-, and height-specific population. Breastfeeding duration was divided into non-breastfeeding, 0−5 months, 6−12 months, and >12 months. Information on demographic, parental or family factors and dietary behaviors was collected through a self-administered questionnaire. Multivariable linear regression and logistic regression models were applied to assess the relationships of breastfeeding duration with BP levels and BP Z scores and with HBP, respectively. Stratified analyses were performed to further investigate the potential subgroup-specific associations. The reported prolonged breastfeeding (>12 months) rate was 22.53% in the total population. After full adjustment, compared to the non-breastfeeding group, breastfeeding for 6−12 months was correlated with 0.43 (95% CI: −0.75, −0.11) and 0.36 (95% CI: −0.61, −0.12) mmHg lower levels of SBP and DBP, respectively. Similar decrease trends were found for BP Z scores. Prolonged breastfeeding (>12 months) was associated with 1.33 (95% CI: 1.12, 1.58) and 1.12 (95% CI: 0.94, 1.33) higher odds of HBP in boys and girls, respectively. Based on nationally representative data, there was no evidence that a longer duration of breastfeeding is protective against childhood HBP. Breastfeeding for 6−12 months may be beneficial to BP, while prolonged breastfeeding durations might increase the odds of HBP in children and adolescents.

Mixed milk feeding: a systematic review and meta-analysis of its prevalence and drivers

CONTEXT

Extensive literature is available on exclusive breastfeeding and formula-feeding practices and health effects. In contrast, limited and unstructured literature exists on mixed milk feeding (MMF), here defined as the combination of breastfeeding and formula feeding during the same period in term infants > 72 hours old (inclusion criterion).

OBJECTIVE

A systematic review and meta-analysis were performed, following the Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines, on the global prevalence of MMF (primary outcome) and related drivers and practices (secondary outcomes).

DATA SOURCES

The search of MMF in generally healthy populations was conducted across 6 databases, restricted to publications from January 2000 to August 2018 in English, Spanish, French, and Mandarin.

DATA EXTRACTION

Two reviewers independently performed screenings and data extraction according to a priori inclusion and exclusion criteria.

DATA ANALYSIS

Of the 2931 abstracts identified, 151 full-text publications were included for data extraction and 96 of those were included for data synthesis (the majority of those were cross-sectional and cohort studies). The authors summarized data across 5 different categories (feeding intention prenatally, and 4 age intervals between > 72 hours and > 6-23 months) and 5 regional subgroups. The overall prevalence of MMF across different age intervals and regions varied between 23% and 32%; the highest rate was found for the age group 4-6 months (32%; 95% confidence interval, 27%-38%); regional comparisons indicated highest MMF rates in Asia (34%), North and South America (33%), and Middle East and Africa together (36%), using a random effects meta-analysis model for proportions. Some drivers and practices for MMF were identified.

CONCLUSION

MMF is a widespread feeding reality. A shared and aligned definition of MMF will help shed light on this feeding practice and evaluate its influence on the duration of total breastfeeding, as well as on infants' nutrition status, growth, development, and health status in the short and long terms. PROSPERO registration number CRD42018105337.

Association between birth weight and childhood cardiovascular disease risk factors in West Virginia

The reported associations between birth weight and childhood cardiovascular disease (CVD) risk factors have been inconsistent. In this study, we investigated the relationship between birth weight and CVD risk factors at 11 years of age. This study used longitudinally linked data from three cross-sectional datasets (N = 22,136) in West Virginia; analysis was restricted to children born full-term (N = 19,583). The outcome variables included resting blood pressure [systolic blood pressure (SBP), diastolic blood pressure (DBP)] and lipid profile [total cholesterol (TC), low-density lipoprotein (LDL) cholesterol, high-density lipoprotein (HDL) cholesterol, non-HDL, and triglycerides (TG)]. Multiple regression analyses were performed, adjusting for child's body mass index (BMI), sociodemographics, and lifestyle characteristics. Unadjusted analyses showed a statistically significant association between birth weight and SBP, DBP, HDL, and TG. When adjusted for the child's BMI, the association between birth weight and HDL [b = 0.14 (95% CI: 0.11, 0.18) mg/dl per 1000 g increase] and between birth weight and TG [b = -0.007 (-0.008, -0.005) mg/dl per 1000 g increase] remained statistically significant. In the fully adjusted model, low birth weight was associated with higher LDL, non-HDL, and TGs, and lower HDL levels. The child's current BMI at 11 years of age partially (for HDL, non-HDL, and TG) and fully mediated (for SBP and DBP) the relationship between birth weight and select CVD risk factors. While effects were modest, these risk factors may persist and amplify with age, leading to potentially unfavorable consequences in later adulthood.

Breastfeeding in Infancy and Lipid Profile in Adolescence

OBJECTIVES

Breast milk has higher cholesterol than formula. Infants who are breastfed have different cholesterol synthesis and metabolism in infancy than infants who are formula fed. Little is known as to whether breastfeeding is associated with subsequent lipid profile, independent of adiposity. We assessed the association of breastfeeding in early infancy with lipid profile and adiposity at ∼17.5 years in a setting where exclusive breastfeeding is not associated with higher socioeconomic position.

METHODS

We used multivariable linear regression with multiple imputation and inverse probability weighting to examine the associations of contemporaneously reported feeding in the first 3 months of life (exclusive breastfeeding [7.5%], mixed feeding [40%], or always formula feeding [52%]) with lipids and adiposity at ∼17.5 years in 3261 participants in the Hong Kong Chinese birth cohort Children of 1997, adjusting for sex, birth weight, gestational weeks, parity, pregnancy characteristics, parents' highest education, mother's place of birth, and age at follow-up.

RESULTS

Exclusive breastfeeding, but not mixed feeding at 0 to 3 months, compared with formula feeding was associated with lower total cholesterol and low-density lipoprotein cholesterol but not with high-density lipoprotein cholesterol at ∼17.5 years. BMI and fat percentage measured by bioimpedance did not differ by type of infant feeding.

CONCLUSIONS

Exclusive breastfeeding in early infancy may promote a healthier lipid profile in late adolescence through mechanisms unrelated to adiposity, implicating its potential long-term benefits for cardiovascular health.

Association Between Breastfeeding and Childhood Cardiovascular Disease Risk Factors

Introduction The immediate benefits of breastfeeding are well-established but the long-term health benefits are less well-known. West Virginia (WV) has a higher prevalence of cardiovascular disease (CVD) and lower breastfeeding rates compared to national averages. There is a paucity of research examining the relationship between breastfeeding and subsequent childhood CVD risk factors, an issue of particular relevance in WV. Methods This study used longitudinally linked data from three cross-sectional datasets in WV (N = 11,980). The information on breastfeeding was obtained retrospectively via parental recall when the child was in the fifth grade. The outcome variables included blood pressure measures [systolic blood pressure (SBP), diastolic blood pressure (DBP)] and lipid profile [total cholesterol (TC), low-density lipoprotein cholesterol (LDL), high-density lipoprotein cholesterol (HDL), non-HDL, and triglycerides (TG)]. Multiple regression analyses were performed, adjusting for childhood body mass index (BMI) and additional covariates. Results Only 43% of mothers self-reported ever breastfeeding. The unadjusted analysis showed that children who were ever vs. never breastfed had significantly lower SBP (b = - 1.39 mmHg; 95% CI - 1.97, - 0.81), DBP (b = - 0.79 mmHg; 95% CI - 1.26, - 0.33), log-TG (b = - 0.08; 95% CI - 0.1, - 0.05), and higher HDL (b = 0.95 mg/dL; 95% CI 0.33, 1.56). After adjustment for the child's BMI, socio-demographic and lifestyle factors, log-TG remained significantly associated with breastfeeding (b = - 0.04; 95% CI - 0.06, - 0.01; p = 0.01). Conclusion The observed protective effect of any breastfeeding on childhood TG level was small but significant. This finding provides some support for a protective effect of breastfeeding on later CVD risk.

In utero exposure to gestational diabetes and adiposity: does breastfeeding make a difference?

BACKGROUND/OBJECTIVES

Short-term breastfeeding from mothers with gestational diabetes (GDM) may programme metabolism and increase offspring diabetes risk. We examined the association of in utero GDM exposure with adiposity from infancy to adolescence, and whether any association was modified by breastfeeding during early infancy.

METHODS

In the prospective Chinese birth cohort "Children of 1997" (n = 7342, 88% follow-up rate), generalised estimate equations with multiple imputation were used to assess associations of in utero GDM exposure with age- and sex-specific body mass index (BMI) z-score during infancy (3 and 9 months), childhood (2- < 8 years) and adolescence (8-16 years), adjusted for sex, parity, maternal age, birth place, preeclampisa, smoking, and family socio-economic position. We also tested whether the associations differed by mode of infant feeding (always formula-fed, mixed, always breastfed) during the first three months of life.

RESULTS

In utero GDM exposure (7.5%) was associated with a lower BMI z-score during infancy (-0.13, 95% confidence interval (CI) -0.22, -0.05) but higher BMI z-scores during childhood (0.14, 95% CI 0.03, 0.25) and adolescence (0.25 95% CI 0.11, 0.38). Breastfeeding for the first three months did not modify the association of in utero GDM status with subsequent BMI (all p values for interaction >0.4).

CONCLUSIONS

In utero GDM exposure was associated with greater adiposity during childhood and adolescence. Breastfeeding in early infancy from mothers with GDM was not associated with greater adiposity in children and thus should still be encouraged.

The Associations of Breast Feeding with Infant Growth and Body Mass Index to 16 years: 'Children of 1997'

BACKGROUND

Controversial findings concerning associations of breast feeding with growth have been reported. This study examined whether the associations of breast feeding with early growth trajectories and body mass index to 16 years differed by sex or age.

METHODS

In Hong Kong's 'Children of 1997' population-representative birth cohort, contemporaneously reported breast-feeding status in the first 3 months was classified as exclusive breast feeding (BF) (n = 470), mixed feeding (MF) (n = 2693), and formula feeding (FF) (n = 4204). Adjusted sex- and age-specific associations of breast feeding with infant growth (gains in weight-for-age z scores (WAZ), length/height-for-age z scores (LAZ), and body-mass-index-for-age z score (BAZ) based on the World Health Organization standards/references from birth to 36 months) were assessed using linear regression and mixed modelling, respectively. Adjusted sex-specific associations of breast feeding with average BAZ from 3 months to 16 years were assessed using generalized estimating equation. Potential confounders were maternal and infant characteristics, and household income.

RESULTS

Among 7367 children, associations of breast feeding with infant growth did not vary by sex, but WAZ gains varied by age. Greater WAZ gains were observed in BF than FF infants from 0 to 3 months but in FF than BF infants from 3 to 9 months. Breast feeding was not associated with overall BAZ from 3 months to 16 years, with no differences by sex.

CONCLUSIONS

Our findings suggest that breast feeding may only have short-term effects on growth. Further studies of the role of breast feeding in other metabolic diseases may be needed.

The association of breastfeeding with insulin resistance at 17 years: Prospective observations from Hong Kong's "Children of 1997" birth cohort

Breastfeeding has many benefits for mother and infant. Whether breastfeeding also protects against type 2 diabetes is unclear. To clarify the role of breastfeeding in type 2 diabetes, we assessed the association of breastfeeding with insulin resistance in late adolescence in a birth cohort from a non-Western setting where breastfeeding was not associated with higher socio-economic position. We used multivariable linear regression, with multiple imputation and inverse probability weighting, to examine the adjusted associations of contemporaneously reported feeding in the first 3 months of life (exclusively breastfed, mixed feeding, or always formula-fed) with fasting glucose, fasting insulin, and homeostasis model assessment of insulin resistance (HOMA-IR) at 17 years in a subset (n = 710, 8.6% of entire cohort) of the Hong Kong Chinese birth cohort "Children of 1997." We found a graded association of breastfeeding exclusivity in the first 3 months of life with lower fasting insulin and HOMA-IR (p-for-trend < .05), but not fasting glucose, at 17 years. Exclusively breastfed adolescents (7%) had nonsignificantly lowest fasting insulin and HOMA-IR, adjusted for sex, birth weight, parity, length of gestation, pregnancy characteristics, parents' education, and mother's place of birth. Exclusively breastfeeding for 3 months may be causally associated with lower insulin resistance in late adolescence. Further follow-up studies into adulthood are required to clarify the long-term protection of breastfeeding from type 2 diabetes.

Associations of Infant Feeding and Timing of Weight Gain and Linear Growth during Early Life with Childhood Blood Pressure: Findings from a Prospective Population Based Cohort Study

Objective

Small birth size and rapid postnatal growth have been associated with higher future blood pressure. The timing of these effects, the relative importance of weight gain and linear growth and the role of infant feeding need to be clarified.

Methods

We assessed how blood pressure relates to birth weight, infant and childhood growth and infant feeding (duration of exclusive breastfeeding and timing of introduction of complementary feeding) in 2227 children aged 5 years from a prospective cohort study (Amsterdam Born Children and their Development). Postnatal growth was represented by statistically independent measures of relative weight gain (weight gain independent of height) and linear growth in four age periods during infancy (0–1 month; 1–3 months; 3–6 months; 6–12 months) and from 12 months to 5 years.

Results

Lower birth weight was associated with higher childhood diastolic blood pressure (-0.38 mm Hg.SD^-1; P = 0.007). Faster relative weight gain and linear growth after 1 month were positively associated with systolic and diastolic blood pressure. Associations of linear growth with systolic blood pressure ranged from 0.47 to 1.49 mm Hg.SD^-1; P<0.01 for all. Coefficients were similar for different periods of infancy and also for relative weight gain and linear growth. Compared to breastfeeding <1 month, breastfeeding >1 month was associated with lower blood pressure (e.g. >6 months -1.56 mm Hg systolic blood pressure; P<0.001). Compared to >6 months, introduction of complementary feeding <6 months was associated with higher blood pressure (e.g. 4–6 months 0.91 mm Hg systolic blood pressure; P = 0.004).

Conclusions

After the age of one month faster growth in either weight or height is associated with higher childhood blood pressure. It is unknown whether faster weight gain and linear growth carry the same risk for adult hypertension and cardiovascular morbidity. Longer breastfeeding and delayed introduction of complementary feeding may be associated with lower adult blood pressure.

Predictors of blood pressure at 7-13 years: The "new millennium baby" study

BACKGROUND AND AIMS

The purpose of this study is to evaluate the association between blood pressure (BP) at 7-13 years of age and body mass index (BMI), early feeding, lifestyle indicators, and parental characteristics.

METHODS AND RESULTS

Retrospective plus cross-sectional cohort study was started in 1294 children born in 2000-2004, right from their birth in primary care settings. Early feeding was estimated by measuring breast-feeding (BF) duration, complementary feeding (CF) introduction time, and lifestyle indicators such as daily screen time and weekly extracurricular sports activity time. Parental education, smoking, and obesity-related diseases were also considered. Multivariable linear regression and mediation analysis were used. CF introduction at 5-6 months of age was a negative predictor of systolic and diastolic BP (mean systolic BP-standard deviation score (SDS) -0.38 [95% CI: -0.47, -0.29] (p < 0.001); mean diastolic BP-SDS -0.32 [95% CI: -0.40, -0.24]) (p < 0.001); BMI was a positive predictor of systolic and diastolic BP (p < 0.001); and parental hypertension was a positive predictor of diastolic BP (p < 0.05). Predictors of mean BMI-SDS at 7-13 years of age were birth weight, screen time, and parental obesity and smoking (p < 0.001). BF had no effect on BP or BMI. Mediation analysis showed virtually no indication of the effect of CF on BP mediated by BMI.

CONCLUSIONS

CF introduction between 5 and 6 months of age could be associated with low BP at 7-13 years. The effect of CF on BP seems to be independent of BMI. Low screen time is associated with low BMI. CF time may play a role in the occurrence of surrogates of noncommunicable disorders in future.

Associations of Birth Order with Early Adolescent Growth, Pubertal Onset, Blood Pressure and Size: Evidence from Hong Kong's "Children of 1997" Birth Cohort

Background

Birth order has been proposed as a cardiovascular risk factor, because the lower birth weight and greater infant weight gain typical of firstborns could programme metabolism detrimentally.

Methods

We examined the associations of birth order (firstborn or laterborn) with birth weight-for-gestational age, length/height and body mass index (BMI) z-scores during infancy, childhood, and puberty using generalized estimating equations, with age at pubertal onset using interval-censored regression and with age-, sex- and height-standardized blood pressure, height and BMI z-scores at 13 years using linear regression in a population-representative Chinese birth cohort: “Children of 1997” (n = 8,327).

Results

Compared with laterborns, firstborns had lower birth weight-for-gestational age (mean difference = -0.18 z-score, 95% confidence interval (CI) -0.23, -0.14), lower infant BMI (-0.09 z-score, 95% CI -0.14, -0.04), greater childhood height (0.10 z-score, 95% CI 0.05, 0.14) and BMI (0.08 z-score, 95% CI 0.03, 0.14), but not greater pubertal BMI (0.05 z-score, 95% CI -0.02, 0.11), adjusted for sex, parental age, birthplace, education and income. Firstborns had earlier onset of pubic hair (time ratio = 0.988, 95% CI 0.980, 0.996), but not breast or genitalia, development. Firstborns had greater BMI (0.07 z-score, 95% CI 0.002, 0.15), but not height (0.05 z-score, 95% CI -0.01, 0.11), at 13 years, but similar blood pressure.

Conclusions

Differences by birth order continue into early adolescence with firstborns being heavier with earlier pubic hair development, which could indicate long-term cardiovascular risk.

Breastfeeding and childhood hospitalizations for asthma and other wheezing disorders

PURPOSE

Observationally in Western settings, breastfeeding is associated with less childhood wheezing disorders but may be confounded by socioeconomic position. We examined the association of breastfeeding with asthma and other wheezing disorders in a developed non-Western setting with unique social patterning of breastfeeding.

METHODS

Using Cox regression, we examined the adjusted associations of breastfeeding with public hospital admissions for asthma, bronchitis, and bronchiolitis (International Classification of Diseases, Ninth Version. Clinical Modification: 466, 490, and 493) from 3 months to 12 years in a population-representative birth cohort of 8327 Hong Kong Chinese children.

RESULTS

We did not find an association of exclusive breastfeeding for 3 months or more, compared with never breastfeeding, with hospitalization for asthma, bronchitis, and bronchiolitis to 12 years (hazard ratio [HR], 0.89; 95% confidence interval [CI], 0.63-1.25) nor for partial breastfeeding for any length of time or exclusive breastfeeding for less than 3 months (HR, 1.02; 95% CI, 0.86-1.21), adjusted for infant and parental characteristics and socioeconomic position. We also did not find an association of exclusive breastfeeding for 3 months or more with hospitalization for asthma only (International Classification of Diseases, Ninth Version. Clinical Modification: 493) (HR, 1.27; 95% CI, 0.82-1.98).

CONCLUSIONS

In a large population-representative Chinese birth cohort, we did not find an association of breastfeeding with childhood hospitalizations for asthma and other wheezing disorders.

Breast feeding and early adolescent behaviour, self-esteem and depression: Hong Kong's 'Children of 1997' birth cohort

OBJECTIVE

Breast feeding may contribute to neurological development and hence mental health. However, associations from Western populations are unclear, and most likely confounded by socioeconomic position (SEP), making evidence from other sociocultural settings valuable. We examined whether breast feeding was associated with early adolescent emotional and behavioural problems, self-esteem and depressive symptoms in a non-Western developed setting, where socioeconomic patterning of breast feeding differs from but other postnatal characteristics are similar to Western settings.

DESIGN

The adjusted associations of breast feeding with emotional and behavioural problems assessed from parent-reported Rutter z-score at ~11 years (n=5598, 67% follow-up), self-reported self-esteem z-score at ~11 years (n=6937, 84%) and depressive symptoms assessed from self-reported Patient Health Questionnaire-9 z-score at ~13 years (n=5797, 70%) were examined using multivariable linear regression in a population-representative Hong Kong Chinese birth cohort, 'Children of 1997'.

RESULTS

Mothers from families with higher education tended to start but not sustain breast feeding, whereas migrant mothers tended to start and sustain breast feeding. Breast feeding for 3+ months had mostly null associations with Rutter score, self-esteem or depressive symptoms adjusted for sex, age, survey mode, SEP, parents' age, birth weight-for-gestational age, birth order and secondhand smoke exposure, although partial breast feeding for any length of time or exclusive breast feeding for <3 months was associated with poorer behaviour (higher Rutter z-score (0.10, 95% CI 0.05 to 0.16)) and lower self-esteem (-0.09, 95% CI -0.14 to -0.04).

CONCLUSIONS

In a non-Western developed setting, breast feeding was inconsistently associated with several early adolescent mental health measures suggesting a reflection of setting specific unmeasured confounding.