Breastfeeding and infant size: evidence of reverse causality

Infant feeding practices and body mass index up to 7.5 years in the French nationwide ELFE study

BACKGROUND/OBJECTIVES

The infant diet represents one of the main modifiable determinants of early growth. This study aimed to investigate the associations of infant feeding practices with body mass index (BMI) until 7.5 years.

SUBJECTS/METHODS

Analyses were based on data from the French nationwide ELFE birth cohort. Data on breastfeeding (BF) and complementary feeding (CF) were collected monthly from 2 to 10 months. Infant feeding practices were characterized using principal component analyses (PCA) and hierarchical ascendant classification. BMI z-score was computed at 1, 2, 3, 5 and 7.5 years, from data collected in the child's health booklet; 7.5-year overweight was defined according to IOTF references. Associations between infant feeding practices and BMI were investigated by linear regression models adjusted for main confounders.

RESULTS

Ever breastfeeding was not associated with BMI up to 7.5 years. Compared to intermediate breastfeeding duration (1 to <3 months), longer breastfeeding duration (≥6 months) was related to lower 1-year BMI, but not at older ages. Compared to the recommended age at CF introduction (4-6 months), early CF (<4 months) was related to higher BMI up to 5 years with a similar trend at 7.5 years, but not to the risk of overweight. The PCA patterns characterized by early baby cereal introduction and late food pieces introduction or by frequent intake of main food groups were related to a lower BMI up to 7.5 years.

CONCLUSION

Breastfeeding was related with a lower BMI in infancy but not thereafter, whereas an early CF initiation (<4 months) was associated with a higher BMI in childhood.

Worldwide trends in underweight and obesity from 1990 to 2022: a pooled analysis of 3663 population-representative studies with 222 million children, adolescents, and adults

BACKGROUND

Underweight and obesity are associated with adverse health outcomes throughout the life course. We estimated the individual and combined prevalence of underweight or thinness and obesity, and their changes, from 1990 to 2022 for adults and school-aged children and adolescents in 200 countries and territories.

METHODS

We used data from 3663 population-based studies with 222 million participants that measured height and weight in representative samples of the general population. We used a Bayesian hierarchical model to estimate trends in the prevalence of different BMI categories, separately for adults (age ≥20 years) and school-aged children and adolescents (age 5-19 years), from 1990 to 2022 for 200 countries and territories. For adults, we report the individual and combined prevalence of underweight (BMI <18·5 kg/m2) and obesity (BMI ≥30 kg/m2). For school-aged children and adolescents, we report thinness (BMI <2 SD below the median of the WHO growth reference) and obesity (BMI >2 SD above the median).

FINDINGS

From 1990 to 2022, the combined prevalence of underweight and obesity in adults decreased in 11 countries (6%) for women and 17 (9%) for men with a posterior probability of at least 0·80 that the observed changes were true decreases. The combined prevalence increased in 162 countries (81%) for women and 140 countries (70%) for men with a posterior probability of at least 0·80. In 2022, the combined prevalence of underweight and obesity was highest in island nations in the Caribbean and Polynesia and Micronesia, and countries in the Middle East and north Africa. Obesity prevalence was higher than underweight with posterior probability of at least 0·80 in 177 countries (89%) for women and 145 (73%) for men in 2022, whereas the converse was true in 16 countries (8%) for women, and 39 (20%) for men. From 1990 to 2022, the combined prevalence of thinness and obesity decreased among girls in five countries (3%) and among boys in 15 countries (8%) with a posterior probability of at least 0·80, and increased among girls in 140 countries (70%) and boys in 137 countries (69%) with a posterior probability of at least 0·80. The countries with highest combined prevalence of thinness and obesity in school-aged children and adolescents in 2022 were in Polynesia and Micronesia and the Caribbean for both sexes, and Chile and Qatar for boys. Combined prevalence was also high in some countries in south Asia, such as India and Pakistan, where thinness remained prevalent despite having declined. In 2022, obesity in school-aged children and adolescents was more prevalent than thinness with a posterior probability of at least 0·80 among girls in 133 countries (67%) and boys in 125 countries (63%), whereas the converse was true in 35 countries (18%) and 42 countries (21%), respectively. In almost all countries for both adults and school-aged children and adolescents, the increases in double burden were driven by increases in obesity, and decreases in double burden by declining underweight or thinness.

INTERPRETATION

The combined burden of underweight and obesity has increased in most countries, driven by an increase in obesity, while underweight and thinness remain prevalent in south Asia and parts of Africa. A healthy nutrition transition that enhances access to nutritious foods is needed to address the remaining burden of underweight while curbing and reversing the increase in obesity.

FUNDING

UK Medical Research Council, UK Research and Innovation (Research England), UK Research and Innovation (Innovate UK), and European Union.

Longitudinal patterns of breastfeeding and its association with adiposity and subjective indicators of satiety/appetite in the first 2 years of life

Evidence about the association between breastfeeding and its duration with growth, appetite and satiety indicators, and adiposity in low and middle-income countries facing nutritional transition is scarce. The aim of this study was to evaluate the association between longitudinal patterns of breastfeeding (exclusive [EBF] and continued [CBF]) with adiposity and growth, and the mediating role of appetite and satiety indicators in these associations in Mexican children during the first 2 years of life. Information from 378 mother-child pairs from the MAS-Lactancia birth cohort was analysed. Information was collected at birth and at months 1, 3, 6, 9, 12, 18 and 24 of life. Duration of EBF and CBF was computed. Linear mixed models were used to assess the association of EBF and CBF with growth and adiposity. Path analysis was used for mediation analysis. Compared with the reference group (EBF duration <1 month), males with >3 to ≤6 months of EBF had less abdominal circumference (β = -0.66, p = 0.05), Z-score weight-for-length (β = -0.17, p = 0.19) and length-for-age (β = -0.49, p < 0.01). Participants without CBF beyond 6 months had higher BMI Z-score (β = 0.19, p < 0.01), abdominal circumference (β = 0.62, p < 0.01) and skinfold sum (β = 0.80, p = 0.09), and o difference in length-for-age. For EBF, mediation was confirmed for satiety responsiveness on the association with BMI Z-Score, for food fussiness for the association with abdominal circumference and length-for-age Z-score, and enjoyment of food on the association with length-for-age Z-score. For CBF, mediation was confirmed for food fussiness in the association with length-for-age. This study suggests that a longer exposure to EBF and CBF is associated with lower adiposity in children under 2 years of age, and that this association could be partially mediated by appetite and satiety indicators.

The effect of breastfeeding on children's growth indices up to 6 months: An application of multivariate t linear mixed model

Background

This study aimed to determine the effect of breastfeeding on children's growth indices.

Materials and Methods

Longitudinal data of children's growth (height, weight, and head circumference) were as a dependent variable and type of nutrition as an independent variable with using multivariate t linear mixed model.

Results

The indicated that the height, weight, and head circumference of infants who were fed with breast milk showed a statistically significant difference (P < 0.05) with those of infants receiving formula.

Conclusion

Exclusive feeding with breast milk, especially in the first 6 months of life, has a significant impact on the child's growth indicators compared to formula or, or a combination of both.

Mediators of differences by parental education in weight-related outcomes in childhood and adolescence in Norway

Studies exploring mediators of socioeconomic inequalities in excess weight gain in early-life and subsequent overweight/obesity (OW/OB) among youth are limited. Thus, this study examined the mediating role of prenatal and early postnatal factors and child energy balance-related behaviours (EBRB) in the effects of parental education on (i) excess weight gain from birth to 2 years and (ii) OW/OB at 5, 8 and 14 years. The Norwegian Mother, Father and Child Cohort Study was used to include participants at the ages of 2 (n = 59,597), 5 (n = 27,134), 8 (n = 28,285) and 14 (n = 11,278) years. Causal mediation analyses using the inverse odds weighting approach were conducted. Children of low-educated parents had a higher conditional excess weight gain at 2 years compared to children of high-educated parents (total effect, RRTE = 1.06; 95% CI 1.01, 1.10). The joint mediation effects of the prenatal and early postnatal factors explained most of the total effect of low education on conditional excess weight gain at 2 years. Children of low-educated parents had a higher risk of OW/OB at 5, 8 and 14 years compared to children of high-educated parents. The mediators jointly explained 63.7%, 67% and 88.9% of the total effect of parental education on OW/OB among 5, 8 and 14 year-old-children, respectively. Of the total mediated effects at 5, 8 and 14 years, the prenatal and early postnatal mediators explained 59.2%, 61.7% and 73.7%, whereas the child EBRB explained 10.3%, 15.8.0%% and 34.8%. The mediators included were found to have a considerable mediating effect in the associations explored, in particular the prenatal and early postnatal factors. If truly causal, the findings could indicate potential targets for interventions to tackle socioeconomic inequalities in OW/OB from birth to adolescence.

Risk factors for discontinuation of exclusive breast feeding within 1month: a retrospective cohort study in Japan

Background

While breastfeeding provides benefits for infants and the mother, many women either do not breastfeed or terminate breastfeeding earlier than recommended. The aim of this analysis was to identify factors associated with early discontinuation of breastfeeding in Japanese women.

Methods

This study used data from medical records of women delivering a singleton live birth between March 2017 and August 2019 in Iwase General Hospital, Fukushima Prefecture, Japan to assess cessation of breastfeeding by the 1-month postpartum appointment. Demographic (age at birth, and employment status), medical (parity, and physical and mental condition of the mother; and infant medical factors, such as sex, Apgar score, and jaundice, among other), and family factors (husband/partner, family members living at the same house, among others) in 734 women who had initiated breastfeeding during their delivery hospital stay were examined, and multiple logistic regression was used to determine significant predictors of early cessation of exclusive breastfeeding.

Results

Bivariate analysis revealed that women who were primipara, unmarried, exposed to secondhand smoke, and employed; those who smoked before pregnancy; and those who had asthma were more likely to discontinue exclusive breastfeeding than other women. Infant factors associated with discontinuation were lower birthweight, earlier gestational age, neonatal intensive care unit admission, treatment for jaundice, or lower weight gain. Multivariable analysis revealed that primiparity, passive smoking before pregnancy, maternal employment, and neonatal jaundice therapy were associated with discontinuation of breastfeeding.

Conclusions

In particular, women whose partners smoked before pregnancy may need to be targeted for additional support for breastfeeding.

Breast-feeding, rapid growth in the first year of life and excess weight at the age of 2 years: the 3D Cohort Study

OBJECTIVE

To assess relationships between breast-feeding, rapid growth in the first year of life and overweight/obesity status at the age of 2 years.

DESIGN

As part of an observational, longitudinal study beginning in early pregnancy, multivariable logistic regressions were used to assess associations between breast-feeding duration (total and exclusive) and rapid weight gain (RWG) between birth and 1 year of age, and to determine predictors of overweight/obesity status at the age of 2 years.

SETTING

Nine hospitals located in the province of Quebec, Canada.

PARTICIPANTS

A sample of 1599 term infants who participated in the 3D Cohort Study.

RESULTS

Children having RWG in the first year and those having excess weight at the age of 2 years accounted for 28 % and < 10 %, respectively. In multivariable models, children breastfed < 6 months and from 6 months to < 1 year were, respectively, 2·5 times (OR 2·45; 95 % CI 1·76, 3·41) and 1·8 times (OR 1·78; 95 % CI 1·29, 2·45) more likely to show RWG up to 1 year of age compared to children breastfed ≥ 1 year. Children exclusively breastfed < 3 months had significantly greater odds of RWG in the first year (OR 1·94; 95 % CI 1·25, 3·04) compared to children exclusively breastfed for ≥ 6 months. Associations between breast-feeding duration (total or exclusive) and excess weight at the age of 2 years were not detected. RWG in the first year was found to be the main predictor of excess weight at the age of 2 years (OR 6·98; 95 % CI 4·35, 11·47).

CONCLUSIONS

The potential beneficial effects of breast-feeding on rate of growth in the first year of life suggest that interventions promoting breast-feeding are relevant for obesity prevention early in life.

Infant feeding practices associated with adiposity peak and rebound in the EDEN mother-child cohort

BACKGROUND/OBJECTIVE

High magnitude of adiposity peak and early adiposity rebound are early risk markers of later obesity. Infant diet represents one of the main modifiable determinants of early growth. This study aimed to investigate the association between infant feeding practices and age and magnitude of adiposity peak and rebound.

SUBJECTS/METHODS

Analyses were based on data from the French EDEN mother-child cohort. Data on breastfeeding and complementary feeding were collected at birth and 4, 8, and 12 months. From clinical examinations and measurements collected in the child's health booklet up to 12 years, individual growth curves were modeled, and ages and magnitudes of adiposity peak and rebound were estimated. Associations between infant feeding practices and growth were investigated by multivariable linear regression in children after testing a child-sex interaction.

RESULTS

In the studied population (n = 1225), adiposity peak occurred at a mean of 9.9 ± 2 months and adiposity rebound at 5.5 ± 1.4 years. Associations between infant feeding practices and adiposity peak or rebound were moderated by child sex. For girls, each additional month of breastfeeding was related to a 2-day increase in the age at adiposity peak (p < 0.001), and an 18-day increase in the age at adiposity peak (p = 0.004). Whereas for boys, each additional month for the age at complementary food introduction was associated with a 29-day increase in the age at adiposity rebound (p = 0.02). For boys, long breastfeeding duration was only related to reduced body mass index at adiposity peak.

CONCLUSIONS

Child sex has a moderating effect on the association between infant feeding practices and adiposity peak or rebound. The well-known association between breastfeeding duration and early growth seems stronger in girls than boys. The association found for complementary feeding in boys may give new insights into preventing obesity.

Cesarean section and breastfeeding outcomes in an Indigenous Qom community with high breastfeeding support

BACKGROUND AND OBJECTIVES

Cesarean section may lead to suboptimal breastfeeding outcomes, though evidence has been mixed. Factors, such as premature birth, birth weight and maternal age may independently increase risk of cesarean and hinder breastfeeding initiation, while maternal preferences, support and sociostructural barriers may influence breastfeeding practices beyond the immediate postpartum period.

METHODOLOGY

We assessed impacts of cesarean section and gestational factors on breastfeeding duration among Indigenous Qom mothers in Argentina who have strong traditional breastfeeding support. We modeled transitions from exclusive breastfeeding to complementary feeding and from complementary feeding to full weaning in a Bayesian time-to-event framework with birth mode and gestational covariates (n = 89 infants).

RESULTS

Estimated median time to full weaning was 30 months. Cesarean-delivered babies were weaned an average of 5 months later adjusting for gestational age, maternal parity and infant sex. No factors were associated with time-to-complementary feeding, and time-to-complementary feeding was not associated with time-to-full weaning.

CONCLUSIONS AND IMPLICATIONS

Among Indigenous Qom mothers in Argentina, cesarean section was not associated with suboptimal breastfeeding outcomes. Although some Qom mothers do experience early breastfeeding problems, particularly following first birth, problems are not more frequent following cesarean delivery. Traditional postpartum kin and community support during prolonged postpartum periods may be instrumental in helping mothers to overcome early breastfeeding problems due to cesarean or other risk factors.

Association of Infant Feeding Methods and Excess Weight from Birth to Age 6

Objective: To examine the associations between human milk feeding method (at the breast versus bottle) and measures of child adiposity during the first 6 years of life. Study Design: Women 12 months' postpartum who delivered a singleton, liveborn infant at >24 weeks gestation completed a survey assessing infant feeding methods and sociodemographics. Mothers were recontacted when the child was 6 years old for a follow-up study assessing growth (N = 269). Children were categorized as ever or never having excess weight using weight-for-age z-scores (WAZ), weight-for-height z-scores (WHZ), and body mass index-for-age z-scores (BMIZ) from birth to 6 years. Modified Poisson regression estimated associations between the duration of each feeding method (exclusive and combined) with excess weight status. Mixed-effect models estimated associations between feeding methods and trajectories of the outcomes. Results: For all feeding practices, increasing duration (in months) was unassociated with the risk of ever having excess weight by age 6 years. Based on mixed models, longer duration of feeding human milk by any method was associated with lower BMIZ (adj β for 6-12 months versus 0-3 months = -0.50, 95% CI: -0.99 to -0.01) and also with the shape of the BMIZ trajectory curve. No other associations between feeding methods and excess weight outcomes were observed. Conclusions: Longer duration of feeding human milk was associated with lower average BMIZ in early childhood but feeding at the breast and feeding expressed milk were not clearly associated with the outcomes when considered separately. Larger studies would help clarify the associations between these specific feeding methods and outcomes. IRB17-00876.

What is normal, healthy growth? Global health, human biology, and parental perspectives

OBJECTIVES

The widespread variation seen in human growth globally stands at odds with the global health perspective that young child growth should not vary across populations if nutritional, environmental and care needs are met. This paper: (1) evaluates the idea that a single standard of "healthy" growth characterizes children under age 5, (2) discusses how variation from this standard is viewed in global health, in human biology and by parents, and (3) explores how views of "normal" growth shape biomedical and parental responses.

METHODS

This paper reviews the anthropological, public health and clinical literature on the nature of child growth and the applicability of World Health Organization Multicenter Growth Reference Study growth standards across contexts.

RESULTS

The considerable variability in child growth across contexts makes it unlikely that any one framework, with issues of sample selection and representativeness, can serve as the model of healthy growth. Global health, human biology and parents differ in the emphasis they place on heredity versus environmental context in understanding this variability, but human biologists and parents tend to view a wider range of growth as "normal." Since both biomedicine and parents base their care decisions on their perceptions of normal, healthy growth, the comparative framework used has important implications for medical treatment and feeding practices.

CONCLUSIONS

A more nuanced approach that incorporates the biology of growth and its association with health outcomes across contexts is critical to identify patterns of healthy growth and to avoid over-reliance on a single standard that may pathologize variability.

Relationship between breastfeeding duration and undernutrition conditions among children aged 0-3 Years in Pakistan

Background

The World Health Organization recommends that a child should be breastfed up to 2 years of age as it is essential for proper growth and development but population-based studies around the world have found conflicting results on the subject. Our study aims to analyze whether there is a relationship between the duration of breastfeeding and undernutrition among children aged from birth up to 3 years of age in Pakistan.

Methods

A secondary analysis of the Pakistan Demographic and Health Survey 2013-2014 with 1072 children aged 3 years and under was conducted. The relationship between breastfeeding duration and undernutrition status was estimated through multiple logistic regression analysis.

Results

The prevalence of stunting, wasting and underweight were 40.6%, 15.8% and 33.9% respectively, while prevalence of severe stunting is at 22.5%; severe wasting at 4.5% and severe underweight at 12.2% in children in our study. Odds of being stunted were significantly higher for children in their 3rd year of life [AOR: 4.35, CI 95% = (2.01, 9.33)] compared to children being breastfed in their 2nd year of life [AOR: 2.43, CI 95% = (1.55, 3.79) after being adjusted for maternal, child, demographic and healthcare access variables. Similarly, children being breastfed in their third year of life were more susceptible to developing severe stunting [AOR: 6.19, CI 95% = (3.31, 11.56)] in comparison to children in their second year [AOR: 2.84, CI 95% = (1.81, 4.46)]. There was no significant association between breastfeeding and wasting/severe wasting, or between breastfeeding and underweight/severe underweight.

Conclusion

Breastfeeding in the 2nd and 3rd year of life was found to have significant relationship with stunting and severe stunting. Mothers need to be educated about the risks of prolonged breastfeeding to reduce the burden of undernutrition in the country.

Characteristics associated with the transition to partial breastfeeding prior to 6 months of age: Data from seven sites in a birth cohort study

The WHO recommends exclusive breastfeeding for the first 6 months of life. However, the transition of the infants' diet to partial breastfeeding with the addition of animal milks and/or solids typically occurs earlier than this. Here, we explored factors associated with the timing of an early transition to partial breastfeeding across seven sites of a birth cohort study in which twice weekly information on infant feeding practices was collected. Infant (size, sex, illness and temperament), maternal (age, education, parity and depressive symptoms), breastfeeding initiation practices (time of initiation, colostrum and pre‐lacteal feeding) and household factors (food security, crowding, assets, income and resources) were considered. Three consecutive caregiver reports of feeding animal milks and/or solids (over a 10‐day period) were characterized as a transition to partial breastfeeding, and Cox proportional hazard models with time (in days) to partial breastfeeding were used to evaluate associations with both fixed and time‐varying characteristics. Overall, 1470 infants were included in this analysis. Median age of transition to partial breastfeeding ranged from 59 days (South Africa and Tanzania) to 178 days (Bangladesh). Overall, higher weight‐for‐length z‐scores were associated with later transitions to partial breastfeeding, as were food insecurity, and infant cough in the past 30 days. Maternal depressive symptoms (evaluated amongst 1227 infants from six sites) were associated with an earlier transition to partial breastfeeding. Relative thinness or heaviness within each site was related to breastfeeding transitions, as opposed to absolute z‐scores. Further research is needed to understand relationships between local perceptions of infant body size and decisions about breastfeeding.

Effects of Breastfeeding, Formula Feeding, and Complementary Feeding on Rapid Weight Gain in the First Year of Life

OBJECTIVE

To determine whether proportion of breast versus formula feeding and timing of complementary food introduction affect the odds of rapid gain in weight status in a diverse sample of infants.

METHODS

Using data from Greenlight Intervention Study, we analyzed the effects of type of milk feeding (breastfeeding, formula, or mixed feeding) from the 2- to 6-month well visits, and the introduction of complementary foods before 4 months on rapid increase in weight-for-age z-score (WAZ) and weight-for-length z-score (WLZ) before 12 months using multivariable logistic regression models.

RESULTS

Of the 865 infants enrolled, 469 had complete data on all variables of interest, and 41% and 33% of those infants had rapid increases in WAZ and WLZ, respectively. Odds of rapid increase in WAZ remained lowest for infants breastfeeding from 2 to 6 months (adjusted odds ratio [aOR] 0.34; 95% confidence interval [CI]: 0.17, 0.69) when compared to infants who were formula-fed. Adjusted for feeding, introduction of complementary foods after 4 months was associated with decreased odds of rapid increase in WLZ (aOR 0.64; 95% CI: 0.42, 0.96).

CONCLUSIONS

Feeding typified by predominant breastfeeding and delaying introduction of complementary foods after 4 months reduces the odds of rapid increases in WAZ and WLZ in the first year of life.

The "weanling's dilemma" revisited: Evolving bodies of evidence and the problem of infant paleodietary interpretation

Breastfeeding is known to be a powerful mediator of maternal and childhood health, with impacts throughout the life course. Paleodietary studies of the past 30 years have accordingly taken an enduring interest in the health and diet of young children as a potential indicator of population fertility, subsistence, and mortality patterns. While progress has been made in recent decades toward acknowledging the agency of children, many paleodietary reconstructions have failed to incorporate developments in cognate disciplines revealing synergistic dynamics between maternal and offspring biology. Paleodietary interpretation has relied heavily on the "weanling's dilemma," in which infants are thought to face a bleak choice between loss of immunity or malnutrition. Using a review of immunological and epidemiological evidence for the dynamic and supportive role that breastfeeding plays throughout the complementary feeding period, this article offers context and nuance for understanding past feeding transitions. We suggest that future interpretative frameworks for infant paleodietary and bioarchaeological research should include a broad knowledge base that keeps pace with relevant developments outside of those disciplines.

Early-Life Predictors of Systolic Blood Pressure Trajectories From Infancy to Adolescence: Findings From Project Viva

Childhood blood pressure (BP) is a strong predictor of later risk of cardiovascular disease. However, few studies have assessed dynamic BP trajectories throughout the early-life period. We investigated the relationship between early-life factors and systolic BP (SBP) from infancy to adolescence using linear spline mixed-effects models among 1,370 children from Project Viva, a Boston, Massachusetts-area cohort recruited in 1999-2002. After adjusting for confounders and child height, we observed higher SBP in children exposed to gestational diabetes mellitus (vs. normoglycemia; age 3 years: β = 3.16 mm Hg (95% confidence interval (CI): 0.28, 6.04); age 6 years: β = 1.83 mm Hg (95% CI: 0.06, 3.60)), hypertensive disorders of pregnancy (vs. normal maternal BP; age 6 years: β = 1.39 mm Hg (95% CI: 0.10, 2.67); age 9 years: β = 1.84 mm Hg (95% CI: 0.34, 3.34); age 12 years: β = 1.70 mm Hg (95% CI: 0.48, 2.92)), higher neonatal SBP (per 10-mm Hg increase; age 3 years: β = 1.26 mm Hg (95% CI: 0.42, 2.09); age 6 years: β = 1.00 mm Hg (95% CI: 0.49, 1.51); age 9 years: β = 0.75 mm Hg (95% CI: 0.17, 1.33)), and formula milk in the first 6 months of life (vs. breast milk only; age 12 years: β = 2.10 mm Hg (95% CI: 0.46, 3.74); age 15 years: β = 3.52 mm Hg (95% CI: 1.40, 5.64); age 18 years: β = 4.94 mm Hg (95% CI: 1.88, 7.99)). Our findings provide evidence of programming of offspring SBP trajectories by gestational diabetes, hypertensive disorders of pregnancy, and formula milk intake and of neonatal BP being a potentially useful marker of childhood BP. These factors could be relevant in identifying children who are at risk of developing elevated BP.

Child stunting is associated with child, maternal, and environmental factors in Vietnam

Child stunting in Vietnam has reduced substantially since the turn of the century but has remained relatively high for several years. We analysed data on children 6-59 months (n = 85,932) from the Vietnam Nutritional Surveillance System, a nationally representative cross-sectional survey. Multivariable Poisson regression models were used to estimate relative risk (RR) of stunting, stratified by child age and ecological region. Covariates at the child, maternal, household, and environmental levels were included based on available data and the World Health Organization conceptual framework on child stunting. Among children 6-23 months, the strongest associations with child stunting were child age in years (RR: 2.49; 95% CI [2.26, 2.73]), maternal height < 145 cm compared with ≥150 cm (RR: 2.04; 95% CI [1.85, 2.26]), living in the Northeast compared with the Southeast (RR: 2.01; 95% CI [1.69, 2.39]), no maternal education compared with a graduate education (RR: 1.77; 95% CI, [1.44, 2.16]), and birthweight < 2,500 g (RR: 1.75; 95% CI [1.55, 1.98]). For children 24-59 months, the strongest associations with child stunting were no maternal education compared with a graduate education (RR: 2.07; 95% CI [1.79, 2.40]), living in the Northeast compared with the Southeast (RR: 1.94; 95% CI [1.74, 2.16]), and maternal height < 145 cm compared with ≥150 cm (RR: 1.81; 95% CI [1.69, 1.94]). Targeted approaches that address the strongest stunting determinants among vulnerable populations are needed and discussed. Multifaceted approaches outside the health sector are also needed to reduce inequalities in socioeconomic status.

Diet, weight gain, and head growth in hospitalized US very preterm infants: a 10-year observational study

BACKGROUND

The benefits of human milk for hospitalized preterm infants are well documented, but the extent to which current human milk diets adequately support growth is uncertain.

OBJECTIVES

1) To quantify differences in weight gain and head growth between very preterm infants fed human milk compared with infant formula; and 2) to describe trends in the magnitude of these differences over time.

METHODS

We studied infants from 777 US NICUs in the Vermont Oxford Network database. We included all surviving infants 23-29 weeks of gestation or 401-1500 g birth weight (maximum gestational age 32 wk) and excluded infants discharged >42 weeks of gestation or with congenital anomalies. In diet-growth analyses, we included infants born 2012-2016 (n = 138,703) to reflect current practice. In trend analyses, we included a 10-y cohort (n = 263,367). We categorized diet at NICU discharge/transfer as: 1) human milk only (no formula or fortifier); 2) human milk with formula or fortifier (mixed); or 3) infant formula only. Outcomes were weight and head circumference z-score change from birth to discharge relative to a fetal reference.

RESULTS

Diet at discharge/transfer was human milk only for 18,274 (6.6%), mixed for 121,621 (44%), and formula only for 137,067 (49%). Weight deviated more from the fetal reference for infants fed both human milk diets compared with formula only (weight z-score change for infants fed human milk only, -0.88; mixed, -0.82; formula only -0.80; P < 0.0001 for diet overall). There were also differences by diet in head z-score change (human milk only, -0.52; mixed, -0.49; formula only, -0.45; P < 0.0001 for diet overall). The magnitude of these differences has diminished substantially over 10 y.

CONCLUSIONS

Very preterm infants receiving human milk compared with infant formula diets have a slower weight gain and head growth at hospital discharge.

Breastfeeding and cardiometabolic markers at age 12: a population-based birth cohort study

BACKGROUND

There is growing evidence for a protective effect of breastfeeding against overweight and diabetes. It is less clear though, whether breastfed infants also have a more favorable cardiometabolic profile in childhood.

OBJECTIVE

We investigated whether children who were breastfed in infancy had more favorable cardiometabolic markers at 12 years of age than children who were never breastfed and received formula milk instead, and whether associations depended on the duration of breastfeeding.

METHODS

In 1509 participants of the population-based PIAMA birth cohort study, cardiometabolic markers were measured at 12 years of age. Duration of breastfeeding in weeks was assessed through parental questionnaires at 3 months and 1 year of age. Multivariable linear regression analysis was used to investigate associations of breastfeeding (any vs. never breastfeeding and duration of breastfeeding in categories <3 months, 3 to <6 months, and ≥6 months breastfeeding vs. never breastfeeding) with systolic and diastolic blood pressure (SBP and DBP, in Z-scores adjusted for age, sex, and height), total-to-high-density lipoprotein cholesterol (TC/HDLC), glycated hemoglobin (HbA1c, in mmol/mol), body mass index (BMI, in Z-scores adjusted for age and sex) and waist circumference (WC, in cm). Multivariable logistic regression was used to investigate the association of breastfeeding with odds of being overweight.

RESULTS

1288 of 1509 children (85.3%) received any breastmilk in infancy. Breastfed children had a lower SBP Z-score (-0.21 SD (≈ -2.29 mmHg), 95% CI -0.37, -0.06), a lower DBP Z-score (-0.10 SD (≈ -1.19 mmHg), 95% CI -0.20, -0.00), a smaller WC (-1.12 cm, 95% CI -2.20; -0.04), and lower odds of being overweight (OR 0.61, 95% CI 0.38, 0.97) than never breastfed children. These associations were not different between children with shorter and longer duration of breastfeeding. No statistically significant differences in TC/HDLC, HbA1c, and BMI were observed between breastfed and never breastfed children.

CONCLUSIONS

We observed that breastfeeding was associated with a lower blood pressure, a smaller waist circumference and a lower risk of overweight in 12-year old children. These associations were independent of the duration of breastfeeding. No associations were observed between breastfeeding and other cardiometabolic markers.

Increasing trend of exclusive breastfeeding over 12 years period (2002-2014) among women in Moshi, Tanzania

BACKGROUND

The World Health Organization has recommended that all infants under 6 months should be exclusively breastfed. An understanding of the trend of exclusive breastfeeding (EBF) over years and over smaller geographical areas is crucial to monitor the progress made in improving the proportions of infants' EBF.

METHODS

Data on infant feeding practices on 2315 mother-infant pairs from 2002 to 2014 were extracted from cohorts of women who delivered in the Moshi Municipality. Descriptive statistics were used to establish the trend of EBF up to 1, 3 and 6 months across waves (2002/2004 = wave I, 2005/2012 = wave II and 2013/2014 = wave III), to relate EBF up to 6 months to wealth quintiles and to HIV status of mothers.

RESULTS

The number of mothers in waves I, II and III were 1656 (71.5%), 256 (11.1%) and 403(17.4%) respectively. The percentages of EBF up to 6 months increased from 5.5, 13.7 to 16.9% from wave I to III. Overall, across the waves, the proportion of EBF up to 6 months among the mothers in the low wealth quintile was 4, 9 and 42%, and 7, 26 and 15% for the ones in the highest wealth quintile. The proportion of EBF up to 6 months has been increasing among HIV positive mothers while fluctuating among their counterparts across the waves.

CONCLUSION

The proportion of EBF up to 6 months has been increasing in the Moshi municipality but is below the national average. While establishing trends of EBF at the national level is commendable, research to establish trends over smaller geographical areas is needed to provide a true picture that may otherwise be masked.

Infant body mass index peak and early childhood cardio-metabolic risk markers in a multi-ethnic Asian birth cohort

Background

: Infant body mass index (BMI) peak has received much interest recently as a potential predictor of future obesity and metabolic risk. No studies, however, have examined infant BMI peak in Asian populations, in whom the risk of metabolic disease is higher.

Methods

: We utilized data among 1020 infants from a mother-offspring cohort, who were Singapore citizens or permanent residents of Chinese, Malay or Indian ethnicity with homogeneous parental ethnic backgrounds, and did not receive chemotherapy, psychotropic drugs or have diabetes mellitus. Ethnicity was self-reported at recruitment and later confirmed using genotype analysis. Subject-specific BMI curves were fitted to infant BMI data using natural cubic splines with random coefficients to account for repeated measures in each child. We estimated characteristics of the child's BMI peak [age and magnitude at peak, average pre-peak velocity (aPPV)]. Systolic (SBP) and diastolic blood pressure (DBP), BMI, sum of skinfolds (SSF) and fat-mass index (FMI) were measured during a follow-up visit at age 48 months. Weighted multivariable linear regression was used to assess the predictors (maternal BMI, gestational weight gain, ethnicity, infant sex, gestational age, birthweight-for-gestational age and breastfeeding duration) of infant BMI peak and its associations with outcomes at 48 months. Comparisons between ethnicities were tested using Bonferroni post-hoc correction.

Results

: Of 1020 infants, 80.5% were followed up at the 48-month visit. Mean (SD) BMI, SSF and FMI at 48 months were 15.6 (1.8) kg/m 2 , 16.5 (5.3) mm and 3.8 (1.3) kg/m 2 , respectively. Mean (SD) age at peak BMI was 6.0 (1.6) months, with a magnitude of 17.2 (1.4) kg/m 2 and pre-peak velocity of 0.7 (0.3) kg/m 2 /month. Compared with Chinese infants, the peak occurred later in Malay {B [95% confidence interval (CI): 0.64 mo (0.36, 0.92)]} and Indian infants [1.11 mo (0.76, 1.46)] and was lower in magnitude in Indian infants [-0.45 kg/m 2 (-0.69, -0.20)]. Adjusting for maternal education, BMI, gestational weight gain, ethnicity, infant sex, gestational age, birthweight-for-gestational-age and breastfeeding duration, higher peak and aPPV were associated with greater BMI, SSF and FMI at 48 months. Age at peak was positively associated with BMI at 48 months [0.15 units (0.09, 0.22)], whereas peak magnitude was associated with SBP [0.17 units (0.05, 0.30)] and DBP at 48 months [0.10 units (0.01, 0.22)]. Older age and higher magnitude at peak were associated with increased risk of overweight at 48 months [Relative Risk (95% CI): 1.35 (1.12-1.62) for age; 1.89 (1.60-2.24) for magnitude]. The associations of BMI peak with BMI and SSF at 48 months were stronger in Malay and Indian children than in Chinese children.

Conclusions

: Ethnic-specific differences in BMI peak characteristics, and associations of BMI peak with early childhood cardio-metabolic markers, suggest an important impact of early BMI development on later metabolic outcomes in Asian populations.

Infant feeding and growth: putting the horse before the cart

Background

Previous observational studies have consistently shown slower weight and length gains in infants with prolonged breastfeeding than in those who were formula-fed from birth or breastfed for a shorter duration. These studies inferred that prolonged breastfeeding causes slower growth in infancy.

Objective

We compared infant growth associated with ≥12 mo of breastfeeding with a shorter duration of breastfeeding on the basis of 3 different analytic approaches to the same data from a randomized trial: intention-to-treat (ITT; "as randomized"), observational ("as fed"), and instrumental variable (IV; by using randomization as an "instrument" to achieve ≥12 mo of breastfeeding).

Design

This was a cluster-randomized trial of a breastfeeding-promotion intervention. Anthropometric measurements were obtained at birth and at 1, 2, 3, 6, 9, and 12 mo.

Results

The 3 analytic approaches yielded different results. The ITT approach showed more rapid growth in the first 2 mo among infants randomly assigned to the breastfeeding-promotion intervention than among control infants, with a decreasing difference over the ensuing months and nearly identical weight, length, and body mass index by 12 mo. The observational analysis showed a different trend: higher weight and length in infants who were breastfed ≥12 mo than in those who were breastfed <12 mo during the first 3 mo and no difference by 6 mo, while infants who were breastfed <12 mo showed increasingly higher weight and length from 6 to 12 mo. The IV analysis showed a temporal pattern that was similar to that seen in the ITT analysis, but with larger (and less precise) differences between infants breastfed for ≥12 compared with <12 mo.

Conclusions

We observed major differences in experimental (ITT and IV) compared with observational approaches to analyzing data obtained from the same children. These approaches lead to opposite causal inferences about the relation between infant feeding and growth and underline the importance of ensuring that the postulated cause (feeding) temporally precedes its hypothesized effect (growth). This trial is registered at http://www.isrctn.org/ as ISRCTN37687716.

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.

What is significant about a single nursing session? An exploratory study

OBJECTIVES

Researchers and clinicians specializing in breastfeeding often rely on measuring one nursing session to characterize the breastfeeding relationship. However, less is known about the descriptive or statistically predictive characteristics of one nursing session. The purposes of this study are twofold: (1) to explore the relationships between variables in a single nursing session; and (2) to study the association between variables in a single nursing session and infant length-for-age (LAZ) and weight-for-age (WAZ).

METHODS

In 63 nursing mother-infant pairs in the United States, anthropometric measurement and observation of a single nursing session revealed six nursing session variables: fore milk fat percent, hind milk fat percent, infant milk intake, duration of session, time since last session, and time of day of session.

RESULTS

A principle factor analysis, undertaken to explore latent variables underlying the six session variables, revealed two factors: (1) loaded highly on fore and hind milk fat percentage, reflecting the overall fat percent in a feed; and (2) loaded highly on milk intake and hind milk fat percentage, indicating the process of breast emptying. In multivariate analyses of all session variables on infant LAZ and WAZ, only hind milk fat percentage was significantly negatively associated with LAZ (β = -0.14, P = .01 (two-tailed), R²  = 0.070), confirmed by a significant negative association between LAZ and factor one (β = -0.32, P = .05 (two-tailed), R²  = 0.090).

CONCLUSIONS

This research describes the dynamics of a single nursing session, and has the potential to help explain variation in infant growth and nutrition.

Differences in growth of Canadian children compared to the WHO 2006 Child Growth Standards

BACKGROUND

To evaluate if there are departures from the WHO Child Growth Standards (WHO-CGS) in postnatal growth of healthy 'Canadian' children in Ontario up to age 2 years, including by infant feeding and ethnicity.

METHODS

We included data on 9964 healthy, singleton children born in Ontario, Canada. Smoothed weight, length and body mass index (BMI) percentile curves were generated using quantile regression for the Canadian cohort from birth to age 2 years. Differences in percentile values were calculated comparing Canadian children vs. the WHO-CGS.

RESULTS

Canadian children under age 2 years were longer than the WHO-CGS at the 10th (0.8 cm), 50th (1.3 cm) and 90th (1.9 cm) percentiles. Canadian children incrementally surpassed the WHO-CGS in weight after age 6 months, and in BMI after 9 months. By age 2 years, the 50th percentile weight of Canadian males was 823 g (95% confidence interval (CI) 680, 965) higher than the WHO-CGS 50th percentile. Weight differences were seen regardless of feeding practice, and were greatest among children of mothers born in Canada and Europe/Western nations, and least for those of East Asian/Pacific or South Asian heritage. Among Canadian breastfed males, 18% (95% CI 16, 19) of newborns and 26% (95% CI 20, 33) toddlers aged 2 years were classified by WHO-CGS as weighing >90th percentile - much higher than the expected rate of 10%. Similarities were seen for differences in BMI.

CONCLUSIONS

Healthy Canadian infants/toddlers are longer and heavier than the WHO-CGS norms. Explanations for these discrepancies require further elucidation.

Studying noncollapsibility of the odds ratio with marginal structural and logistic regression models

One approach to quantifying the magnitude of confounding in observational studies is to compare estimates with and without adjustment for a covariate, but this strategy is known to be defective for noncollapsible measures such as the odds ratio. Comparing estimates from marginal structural and standard logistic regression models, the total difference between crude and conditional effects can be decomposed into the sum of a noncollapsibility effect and confounding bias. We provide an analytic approach to assess the noncollapsibility effect in a point-exposure study and provide a general formula for expressing the noncollapsibility effect. Next, we provide a graphical approach that illustrates the relationship between the noncollapsibility effect and the baseline risk, and reveals the behavior of the noncollapsibility effect for a range of different exposure and covariate effects. Various observations about noncollapsibility can be made from the different scenarios with or without confounding; for example, the magnitude of effect of the covariate plays a more important role in the noncollapsibility effect than does that of the effect of the exposure. In order to explore the noncollapsibility effect of the odds ratio in the presence of time-varying confounding, we simulated an observational cohort study. The magnitude of noncollapsibility was generally comparable to the effect in the point-exposure study in our simulation settings. Finally, in an applied example we demonstrate that collapsibility can have an important impact on estimation in practice.

Sexually dimorphic response to feeding mode in the growth of infants

BACKGROUND

The relation between infant feeding and growth has been extensively evaluated, but studies examining sex differences in the influence of infant milk feeding on growth are limited.

OBJECTIVE

We examined the interaction of infant feeding and sex in relation to infant growth and compared growth trajectories in breastfed and formula-fed boys and girls.

DESIGN

In 932 infants in a Singapore mother-offspring cohort, feeding practices in the first 6 mo were classified into the breastfeeding group (BF), mixed feeding group (MF), and formula feeding group (FF). Infant weight and length were measured and converted to WHO standards for weight-for-age z scores (WAZs) and length-for-age z scores (LAZs). Differences in WAZ and LAZ from birth to 6 mo, 6 to 12 mo, and 12 to 24 mo of age were calculated. Three-way interactions were examined between feeding mode, sex, and age intervals for WAZ and LAZ changes, with adjustment for confounders.

RESULTS

The interaction between feeding mode, sex, and age intervals was significant for LAZ changes (P = 0.003) but not WAZ changes (P = 0.103) after adjustment for potential confounders. Compared with BF girls, BF boys showed similar LAZ gain (+0.28 compared with +0.39, P = 0.544) from 0 to 6 mo of age but greater LAZ gain from 6 to 12 mo of age (+0.39 compared with -0.10, P = 0.008). From 0 to 6 mo of age, FF boys and girls showed greater LAZ gains than their BF counterparts; from 6 to 12 mo of age, FF girls showed higher LAZ gain (+0.25 compared with -0.10, P = 0.031) than BF girls, which was not seen in boys.

CONCLUSIONS

During infancy, there is a sexually dimorphic growth response to the mode of infant milk feeding, raising questions about whether formula feeding ought to remain sex neutral. However, further investigations on sex-specific feeding and infant growth are warranted before a conclusive message can be drawn based on our current findings. This trial was registered at www.clinicaltrials.gov as NCT01174875.

Increased association between endometriosis and endometrial cancer: a nationwide population-based retrospective cohort study

Objective

Association between endometriosis and ovarian cancer has been well established. Nonetheless, endometriosis may also be associated with endometrial cancer because of shared etiological mechanisms of both estrogen stimulation and chronic inflammation; however, the association between these 2 disorders has rarely been investigated.

Methods

The National Health Insurance Research Databases in Taiwan were retrieved and analyzed. The case cohort consisted of patients with a diagnosis of endometriosis between January 1997 and December 2000 (N = 15,488). For the construction of control cohort, 8 age- and sex-matched control patients for every patient in the case cohort were selected using a random sampling method (n = 123,904). All subjects were tracked for 10 years from the date of entry to identify whether they had developed endometrial cancer. The Cox proportional hazards regression model was used to evaluate 10-year event occurrence of endometrial cancer.

Results

During the 10-year follow-up period, 392 participants developed endometrial cancer, with 104 (0.7%) distributed in the case cohort and 288 (0.2%) in the control cohort. Multivariable Cox regression modeling demonstrates a higher risk for developing endometrial cancer in the case cohort than in the control cohort (adjusted hazard ratio [aHR], 2.83; 95% confidence interval [CI], 1.495.35; P < 0.01). Age at diagnosis of endometriosis shows a moderator effect: when 40 years or younger, the risk for developing endometrial cancer was comparable between the case cohort and the control cohort (aHR, 1.42; 95% CI, 0.55–3.70; P = 0.226), whereas when older than 40 years, the risk for developing endometrial cancer was higher in the former group than in the latter group (aHR, 7.08; 95% CI, 2.33–21.55; P = 0.007).

Conclusions

Patients diagnosed with endometriosis may harbor an increased risk for developing endometrial cancer in their later life. Closer monitoring is advised for this patient population.

Associations Between Breast Milk Feeding, Introduction of Solid Foods, and Weight Gain in the First 12 Months of Life

BACKGROUND AND OBJECTIVES

Breast milk feeding and solid food introduction can influence infant growth, but are rarely examined together. The objectives were to describe relationships between feeding practices, feeding practices and weight gain, and how the relationship of breast milk feeding and growth may change when breastfed infants start solid foods before 6 months.

METHODS

Data were analyzed on 438 infants from the Moms2Moms Study (2011-2012, Ohio), using multivariable linear and logistic regression models to explore each of the relationships.

RESULTS

For each additional month of breast milk feeding, solid food introduction was delayed by 1.32 days (95% CI 0.11 to 2.53) and average weight gain per month decreased by 5.05 g (95% CI 7.39 to 2.17). There was no association between solid food introduction and growth.

CONCLUSIONS

Longer breastfeeding duration was associated with slower growth regardless of solid food introduction. Age at solid food introduction was not associated with growth.

Age of introduction of first complementary feeding for infants: a systematic review

Background

Despite a World Health Organization recommendation for exclusive breastfeeding of all full-term infants to 6 months of age, it is not clear what the health implications may be. Breast milk alone may not meet the nutrition needs for all growing infants, leaving them at risk for deficiencies. The objective of this study was to investigate the relationship between moderate (4 months) versus late (6 months) introduction of complementary foods to the full-term breastfed infant on iron status and growth.

Methods

An electronic search of peer-reviewed and gray-literature was conducted for randomized control trials (RCTs) and observational studies related to the timing of introduction of complementary foods. Iron status and growth data from the relevant RCTs were analyzed using RevMan 5.2.11.

Results

Three RCTs and one observational study met the inclusion criteria. Meta-analysis showed significantly higher hemoglobin levels in infants fed solids at 4 months versus those fed solids at 6 months in developing countries [mean difference [MD]: 5.0 g/L; 95 % CI: 1.5, 8.5 g/L; P = 0.005]. Meta-anaysis also showed higher serum ferritin levels in the 4-month group in both developed and developing countries [MD: 26.0 μg/L; 95 % CI: -0.1, 52.1 μg/L, P = 0.050], [MD: 18.9 μg/L; 95 % CI: 0.7, 37.1 μg/L, P = 0.040]. Short follow-up periods and small sample sizes of the included studies were the major limitations.

Conclusions

RCT evidence suggests the rate of iron deficiency anemia in breastfed infants could be positively altered by introduction of solids at 4 months.

Electronic supplementary material

The online version of this article (doi:10.1186/s12887-015-0409-5) contains supplementary material, which is available to authorized users.

Longer breastfeeding duration reduces the positive relationships among gestational weight gain, birth weight and childhood anthropometrics

BACKGROUND

The relationship between gestational weight gain (GWG) and childhood growth remains controversial. An examination on whether infant feeding practices mediate this relationship may improve our understanding of it.

METHODS

We investigated whether the relationships among GWG, birth weight and childhood anthropometrics were mediated through infant feeding practices (breastfeeding duration and age at introduction of solid foods) in a cross-sectional multiethnic study of 1387 mothers and their children aged 0-5.9 years in the USA (2011-2012). Child anthropometrics included age-specific and sex-specific z-scores for weight-for-age (WAZ), height/length-for-age (HAZ), weight-for-height/length (WHZ) and body mass index-for-age (BMIZ); and ulnar length, a marker for limb growth. We used structural equation modelling to calculate standardised path coefficients and total, direct and indirect associations of GWG, birth weight and infant feeding practices with child anthropometrics.

RESULTS

Maternal GWG had a positive indirect association with all anthropometrics mediated via birth weight, whereas longer breastfeeding duration reduced the positive associations of GWG and birth weight with WAZ, WHZ and BMIZ in non-Hispanics (β=-0.077, -0.064 and -0.106, respectively). Longer breastfeeding duration and introducing solid foods at a later age were positively associated with ulnar length (β=0.023 and 0.030, respectively) but not HAZ, suggesting a distinct association, for the first time, with limb growth.

CONCLUSIONS

Findings suggest that promoting longer breastfeeding duration among women with excessive GWG who had high birthweight newborns may mitigate the potential for their offspring to develop obesity. In addition, findings reinforce the importance of promoting appropriate GWG and preventing high birth weight, which are positively associated with childhood anthropometrics.

Associations of infant feeding and timing of linear growth and relative weight gain during early life with childhood body composition

BACKGROUND

Growth and feeding during infancy have been associated with later life body mass index. However, the associations of infant feeding, linear growth and weight gain relative to linear growth with separate components of body composition remain unclear.

METHODS

Of 5551 children with collected growth and infant-feeding data in a prospective cohort study (Amsterdam Born Children and their Development), body composition measured using bioelectrical impedance analysis at the age of 5-6 years was available for 2227 children. We assessed how feeding (duration of full breastfeeding and timing of introduction of complementary feeding) and conditional variables representing linear growth and relative weight gain were associated with childhood fat-free mass (FFM) and fat mass (FM).

RESULTS

Birth weight was positively associated with both FFM and FM in childhood, and more strongly with FFM than FM. Faster linear growth and faster relative weight gain at all ages in infancy were positively associated with childhood FFM and FM. The associations with FM were stronger for relative weight gain than for linear growth (FM z score: β coefficient 0.23 (95% con 0.19 to 0.26), P<0.001 and 0.14 (0.11 to 0.17), P<0.001 per s.d. change in relative weight gain and linear growth between 1 and 3 months, respectively). Compared with full breastfeeding <1 month, full breastfeeding >6 months was associated with lower FM (FM z score: -0.17 (-0.28 to -0.05), P=0.005) and lower FFM (FFM z score: -0.13 (-0.23 to -0.03), P=0.015), as was the introduction of complementary feeding >6 months (FM z score: -0.22 (-0.38 to -0.07), P=0.004), compared with <4 months.

CONCLUSIONS

Faster infant weight gain is associated with a healthier childhood body composition when it is caused by faster linear growth. Full breastfeeding >6 months and introduction of complementary feeding >6 months are associated with lower childhood FM.

A comparison of confounding adjustment methods with an application to early life determinants of childhood obesity

We implemented six confounding adjustment methods: (1) covariate-adjusted regression, (2) propensity score (PS) regression, (3) PS stratification, (4) PS matching with two calipers, (5) inverse probability weighting and (6) doubly robust estimation to examine the associations between the body mass index (BMI) z-score at 3 years and two separate dichotomous exposure measures: exclusive breastfeeding v. formula only (n=437) and cesarean section v. vaginal delivery (n=1236). Data were drawn from a prospective pre-birth cohort study, Project Viva. The goal is to demonstrate the necessity and usefulness, and approaches for multiple confounding adjustment methods to analyze observational data. Unadjusted (univariate) and covariate-adjusted linear regression associations of breastfeeding with BMI z-score were -0.33 (95% CI -0.53, -0.13) and -0.24 (-0.46, -0.02), respectively. The other approaches resulted in smaller n (204-276) because of poor overlap of covariates, but CIs were of similar width except for inverse probability weighting (75% wider) and PS matching with a wider caliper (76% wider). Point estimates ranged widely, however, from -0.01 to -0.38. For cesarean section, because of better covariate overlap, the covariate-adjusted regression estimate (0.20) was remarkably robust to all adjustment methods, and the widths of the 95% CIs differed less than in the breastfeeding example. Choice of covariate adjustment method can matter. Lack of overlap in covariate structure between exposed and unexposed participants in observational studies can lead to erroneous covariate-adjusted estimates and confidence intervals. We recommend inspecting covariate overlap and using multiple confounding adjustment methods. Similar results bring reassurance. Contradictory results suggest issues with either the data or the analytic method.

Breast-feeding and health consequences in early childhood: is there an impact of time-dependent confounding?

BACKGROUND

Estimated effects of breast-feeding on childhood health vary between studies, possibly due to confounding by baseline maternal and child characteristics. Possible time-dependent confounding has received little consideration. Our aim was to evaluate the impact of such confounding.

METHODS

We estimated the relationship between cumulative exclusive breast-feeding up to 6 months and wheezing, rash and body mass index (BMI) at 12 months [in the Whistler cohort (n = 494) and PROBIT (n = 11,463)], and wheezing, rash, asthma, hay fever, eczema, allergy and BMI at age 6.5 years (PROBIT). We adjusted for time-dependent confounding by weight, length, rash, respiratory illness and day care attendance using marginal structural models (MSMs).

RESULTS

Weight and day care attendance appeared potential time-dependent confounders, since these predicted breast-feeding status and were influenced by previous breast-feeding. However, adjustment for time-dependent confounders did not markedly change the estimated associations. For example, in PROBIT the adjusted increase in BMI at 12 months per 1-month increase in exclusive breast-feeding was 0.04 (95% CI -0.09 to 0.01) using logistic regression and -0.06 (95% CI -0.11 to -0.01) using MSM. In Whistler, these estimates were each -0.05 (95% CI -0.10 to 0.00).

CONCLUSIONS

In two cohort studies, there was little evidence of time-dependent confounding by weight, length, rash, respiratory illness or day care attendance of the effects of breast-feeding on early childhood health.

Factors associated with growth patterns from birth to 18 months in a Beninese cohort of children

The aim of this study was to analyze factors influencing the growth pattern of children from birth to 18 months. A longitudinal prospective study was conducted in three maternity wards in Southern Benin. Inclusion took place between June 2007 and July 2008; children were followed-up until 18 months of age. Height-for-age and weight-for-height Z-scores were computed using the newborn's anthropometric measurements taken at delivery, every month up to 6 months and then quarterly. Infant and young child feeding (IYCF) practices and malarial morbidity were recorded. Gestational age was estimated using the Ballard method; William's sex-specific reference curve of birth weight-for-gestational-age was used to determine intrauterine growth retardation (IUGR). Analyses were performed on 520 children using a linear mixed model. Low birth weight (coef=-0.43; p=0.002), IUGR (coef=-0.49; p<0.001), maternal short stature (coef=-0.25; p=0.001) and maternal low weight status (coef=-0.19; p=0.006) were significantly associated with growth impairment. Only LBW (coef=-0.28; p=0.05) and maternal low weight status (coef=-0.23; p=0.004) were associated with wasting. A good IYCF score was positively associated with weight gain (coef=0.14; p<0.001) whereas we found a paradoxical association with length (coef=-0.18; p<0.001). Malaria morbidity was not associated with growth. LBW, IUGR and maternal low weight status and height were important determinants of children's growth. These results reinforce and justify continuing public health initiatives to fight IUGR and LBW and break the intergenerational cycle of malnutrition.

Effects of body size and change in body size from infancy through childhood on body mass index in adulthood

BACKGROUND

Weight and weight gain throughout infancy are related to later obesity, but whether the strength of the associations varies during the infancy period is uncertain.

AIMS

Our aims were to identify the period of infancy when change in body weight has the strongest association with adult body mass index (BMI) and also the extent to which these associations during infancy are mediated through childhood BMI.

METHODS

The Copenhagen Perinatal Cohort, in which participants were followed from birth through 42 years of age, provided information on weight at 12 months and BMI at 42 years for 1633 individuals. Information on weight at birth, 2 weeks, 1, 2, 3, 4 and 6 months was retrieved from health visitors' records and information on BMI at ages 7 and 13 years from school health records. The associations of infant weight and weight gain standard deviation scores (SDS) with adult BMI-SDS were analyzed using multiple linear regression and path analysis.

RESULTS

Higher-weight-SDS at all ages from birth to an age 12 months were associated with higher-BMI-SDS at 42 years (regression coefficients 0.08-0.12). Infant weight gain-SDS was associated with greater BMI-SDS at 42 years only between birth and 3 months (0.09, 95% confidence intervals (CI) 0.04, 0.15) driven by an association between 2 and 3 months (0.12, 95% CI: 0.04, 0.20). The latter was partly mediated through later BMI in the path analysis. Infant weight gain-SDS between 3 and 12 months was not associated with greater BMI-SDS at 42 years.

CONCLUSIONS

Faster weight gain during only the first 3 months of infancy was associated with increased adult BMI, although not in a consistent monthly pattern. Adult BMI is more sensitive to high weight gain during early infancy than late infancy, but not specifically to the first month of life.

EFFECT OF BREASTFEEDING ON GASTROINTESTINAL INFECTION IN INFANTS: A TARGETED MAXIMUM LIKELIHOOD APPROACH FOR CLUSTERED LONGITUDINAL DATA

The PROmotion of Breastfeeding Intervention Trial (PROBIT) cluster-randomized a program encouraging breastfeeding to new mothers in hospital centers. The original studies indicated that this intervention successfully increased duration of breastfeeding and lowered rates of gastrointestinal tract infections in newborns. Additional scientific and popular interest lies in determining the causal effect of longer breastfeeding on gastrointestinal infection. In this study, we estimate the expected infection count under various lengths of breastfeeding in order to estimate the effect of breastfeeding duration on infection. Due to the presence of baseline and time-dependent confounding, specialized "causal" estimation methods are required. We demonstrate the double-robust method of Targeted Maximum Likelihood Estimation (TMLE) in the context of this application and review some related methods and the adjustments required to account for clustering. We compare TMLE (implemented both parametrically and using a data-adaptive algorithm) to other causal methods for this example. In addition, we conduct a simulation study to determine (1) the effectiveness of controlling for clustering indicators when cluster-specific confounders are unmeasured and (2) the importance of using data-adaptive TMLE.

Associations between infant feeding and the size, tempo and velocity of infant weight gain: SITAR analysis of the Gemini twin birth cohort

Objective:

Infant growth trajectories, in terms of size, tempo and velocity, may programme lifelong obesity risk. Timing of breastfeeding cessation and weaning are both implicated in rapid infant growth; we examined the association of both simultaneously with a range of growth parameters.

Design:

Longitudinal population-based twin birth cohort.

Subjects:

The Gemini cohort provided data on 4680 UK infants with a median of 10 (interquartile range=8–15) weight measurements between birth and a median of 6.5 months. Age at breastfeeding cessation and weaning were reported by parents at mean age 8.2 months (s.d.=2.2, range=4–20). Growth trajectories were modelled using SuperImposition by Translation And Rotation (SITAR) to generate three descriptors of individual growth relative to the average trajectory: size (grams), tempo (weeks, indicating the timing of the peak growth rate) and velocity (% difference from average, reflecting mean growth rate). Complex-samples general linear models adjusting for family clustering and confounders examined associations between infant feeding and SITAR parameters.

Results:

Longer breastfeeding (>4 months vs never) was independently associated with lower growth velocity by 6.8% (s.e.=1.3%) and delayed growth tempo by 1.0 (s.e.=0.2 weeks), but not with smaller size. Later weaning (⩾6 months vs <4 months) was independently associated with lower growth velocity by 4.9% (s.e.=1.1%) and smaller size by 102 g (s.e.=25 g).

Conclusions:

Infants breastfed for longer grew slower for longer after birth (later peak growth rate) but were no different in size, while infants weaned later grew slower overall and were smaller but the timing of peak growth did not differ. Slower trajectories with a delayed peak in growth may have beneficial implications for programming later obesity risk. Replication in cohorts with longer follow-up, alternative confounding structures or randomised controlled trials are required to confirm the long-term effects and directionality, and to rule out residual confounding.

Effects of promoting longer-term and exclusive breastfeeding on cardiometabolic risk factors at age 11.5 years: a cluster-randomized, controlled trial

BACKGROUND

The duration and exclusivity of breastfeeding in infancy have been inversely associated with future cardiometabolic risk. We investigated the effects of an experimental intervention to promote increased duration of exclusive breastfeeding on cardiometabolic risk factors in childhood.

METHODS AND RESULTS

We followed-up children in the Promotion of Breastfeeding Intervention Trial, a cluster-randomized trial of a breastfeeding promotion intervention based on the World Health Organization/United Nations Children's Fund Baby-Friendly Hospital Initiative. In 1996 to 1997, 17 046 breastfeeding mother-infant pairs were enrolled from 31 Belarusian maternity hospitals and affiliated polyclinics (16 intervention versus 15 control sites); 13 879 (81.4%) children were followed up at 11.5 years, with 13 616 (79.9%) who had fasted and did not have diabetes mellitus. The outcomes were blood pressure; fasting insulin, adiponectin, glucose, and apolipoprotein A1; and the presence of metabolic syndrome. Analysis was by intention to treat, accounting for clustering within hospitals/clinics. The intervention substantially increased breastfeeding duration and exclusivity in comparison with the control arm (43% versus 6% and 7.9% versus 0.6% exclusively breastfed at 3 and 6 months, respectively). Cluster-adjusted mean differences at 11.5 years between experimental versus control groups were as follows: 1.0 mm Hg (95% confidence interval, -1.1 to 3.1) for systolic and 0.8 mm Hg (-0.6 to 2.3) for diastolic blood pressure; -0.1 mmol/L (-0.2 to 0.1) for glucose; 8% (-3% to 34%) for insulin; -0.3 μg/mL (-1.5 to 0.9) for adiponectin; and 0.0 g/L (-0.1 to 0.1) for apolipoprotein A1. The cluster-adjusted odds ratio for metabolic syndrome, comparing experimental versus control groups, was 1.21 (0.85 to 1.72).

CONCLUSIONS

An intervention to improve breastfeeding duration and exclusivity among healthy term infants did not influence cardiometabolic risk factors in childhood.

CLINICAL TRIAL REGISTRATION

Current Controlled Trials: ISRCTN37687716 (http://www.controlled-trials.com/ISRCTN37687716). URL: http://clinicaltrials.gov. Unique identifier: NCT01561612.

Prenatal and postnatal energetic conditions and sex steroids levels across the first year of life

OBJECTIVES

Human biologists have documented variability in reproductive maturation, fertility, and cancer risk related to developmental conditions. Yet no previous studies have directly examined the impact of prenatal and postnatal energetic environments on sex steroids in infancy, a critical period for hypothalamic-pituitary-gonadal axis development. Thus, we examined the impact of maternal characteristics, birth size, and feeding practices on fecal sex steroid production in a longitudinal sample of 31 American infants followed from 2 weeks to 12 months of age.

METHODS

Maternal characteristics and birth size were collected at study enrollment, infant diet was assessed through weekly 24-h food diaries, and anthropometrics were measured weekly. Fecal estradiol and testosterone levels were assessed weekly using validated microassay RIA techniques. Mixed models were used to test for associations between maternal and birth characteristics, feeding practices, and sex steroids across the first year of life. Formal mediation analysis examined whether the relationship between infant feeding and hormone levels was mediated by infant size.

RESULTS

Maternal and birth characteristics had persistent effects on fecal sex steroid levels, with taller maternal height and larger birth size associated with lower estradiol levels in girls and higher testosterone levels in boys. Infant diet was also associated with sex steroid levels independently of infant size. Formula feeding was associated with higher estradiol levels in boys and girls and with higher testosterone in girls.

CONCLUSION

These results suggest that markers of early energy availability influence sex hormone levels with potential long-term consequences for reproductive development and function.

Breastfeeding, introduction of other foods and effects on health: a systematic literature review for the 5th Nordic Nutrition Recommendations

The present systematic literature review is part of the 5th revision of the Nordic Nutrition Recommendations. The overall aim was to review recent scientific data valid in a Nordic setting on the short- and long-term health effects of breastfeeding (duration of both any and exclusive breastfeeding) and introduction of foods other than breast milk. The initial literature search resulted in 2,011 abstracts; 416 identified as potentially relevant. Full paper review resulted in 60 quality assessed papers (6A, 48B, and 6C). A complementary search found some additional papers. The grade of evidence was classified as convincing, probable, limited-suggestive, and limited-no conclusion. The evidence was convincing of a protective dose/duration effect of breastfeeding against overweight and obesity in childhood and adolescence, overall infections, acute otitis media, and gastrointestinal and respiratory tract infections. The evidence was probable that exclusive breastfeeding for longer than 4 months is associated with slower weight gain during the second half of the first year which could be part of the reason behind the reduced risk of later overweight or obesity. There was also probable evidence that breastfeeding is a protective factor against inflammatory bowel disease, celiac disease, and diabetes (type 1 and 2), provides beneficial effects on IQ and developmental scores of children as well as a small reductive effect on blood pressure and blood cholesterol levels in adulthood. Other associations explored were limited-suggestive or inconclusive. In conclusion, convincing and probable evidence was found for benefits of breastfeeding on several outcomes. The recommendation in NNR2004 about exclusive breastfeeding for 6 months and continued partial breastfeeding thereafter can stand unchanged. The relatively low proportion of infants in the Nordic countries following this recommendation indicates that strategies that protect, support and promote breastfeeding should be enhanced, and should also recognize the benefits for long-term health.

Effects of promoting longer-term and exclusive breastfeeding on adiposity and insulin-like growth factor-I at age 11.5 years: a randomized trial

IMPORTANCE

Evidence that longer-term and exclusive breastfeeding reduces child obesity risk is based on observational studies that are prone to confounding.

OBJECTIVE

To investigate effects of an intervention to promote increased duration and exclusivity of breastfeeding on child adiposity and circulating insulin-like growth factor (IGF)-I, which regulates growth.

DESIGN, SETTING, AND PARTICIPANTS

Cluster-randomized controlled trial in 31 Belarusian maternity hospitals and their affiliated clinics, randomized into 1 of 2 groups: breastfeeding promotion intervention (n = 16) or usual practices (n = 15). Participants were 17,046 breastfeeding mother-infant pairs enrolled in 1996 and 1997, of whom 13,879 (81.4%) were followed up between January 2008 and December 2010 at a median age of 11.5 years.

INTERVENTION

Breastfeeding promotion intervention modeled on the WHO/UNICEF Baby-Friendly Hospital Initiative (World Health Organization/United Nations Children's Fund).

MAIN OUTCOME MEASURES

Body mass index (BMI), fat and fat-free mass indices (FMI and FFMI), percent body fat, waist circumference, triceps and subscapular skinfold thicknesses, overweight and obesity, and whole-blood IGF-I. Primary analysis was based on modified intention-to-treat (without imputation), accounting for clustering within hospitals and clinics.

RESULTS

The experimental intervention substantially increased breastfeeding duration and exclusivity when compared with the control (43% vs 6% exclusively breastfed at 3 months and 7.9% vs 0.6% at 6 months). Cluster-adjusted mean differences in outcomes at 11.5 years of age between experimental vs control groups were: 0.19 (95% CI, -0.09 to 0.46) for BMI; 0.12 (-0.03 to 0.28) for FMI; 0.04 (-0.11 to 0.18) for FFMI; 0.47% (-0.11% to 1.05%) for percent body fat; 0.30 cm (-1.41 to 2.01) for waist circumference; -0.07 mm (-1.71 to 1.57) for triceps and -0.02 mm (-0.79 to 0.75) for subscapular skinfold thicknesses; and -0.02 standard deviations (-0.12 to 0.08) for IGF-I. The cluster-adjusted odds ratio for overweight/obesity (BMI ≥ 85th vs <85th percentile) was 1.18 (95% CI, 1.01 to 1.39) and for obesity (BMI ≥ 95th vs <85th percentile) was 1.17 (95% CI, 0.97 to 1.41).

CONCLUSIONS

AND RELEVANCE Among healthy term infants in Belarus, an intervention that succeeded in improving the duration and exclusivity of breastfeeding did not prevent overweight or obesity, nor did it affect IGF-I levels at age 11.5 years. Breastfeeding has many advantages but population strategies to increase the duration and exclusivity of breastfeeding are unlikely to curb the obesity epidemic.

TRIAL REGISTRATION

isrctn.org: ISRCTN37687716; and clinicaltrials.gov: NCT01561612.

Cohort profile: The promotion of breastfeeding intervention trial (PROBIT)

The PROmotion of Breastfeeding Intervention Trial (PROBIT) is a multicentre, cluster-randomized controlled trial conducted in the Republic of Belarus, in which the experimental intervention was the promotion of increased breastfeeding duration and exclusivity, modelled on the Baby-friendly hospital initiative. Between June 1996 and December 1997, 17,046 mother-infant pairs were recruited during their postpartum hospital stay from 31 maternity hospitals, of which 16 hospitals and their affiliated polyclinics had been randomly assigned to the arm of PROBIT investigating the promotion of breastfeeding and 15 had been assigned to the control arm, in which breastfeeding practices and policies in effect at the time of randomization was continued. Of the mother-infant pairs originally recruited for the study, 16,492 (96.7%) were followed at regular intervals until the infants were 12 months of age (PROBIT I) for the outcomes of breastfeeding duration and exclusivity; gastrointestinal and respiratory infections; and atopic eczema. Subsequently, 13,889 (81.5%) of the children from these mother-infant pairs were followed-up at age 6.5 years (PROBIT II) for anthropometry, blood pressure (BP), behaviour, dental health, cognitive function, asthma and atopy outcomes, and 13,879 (81.4%) children were followed to the age of 11.5 years (PROBIT III) for anthropometry, body composition, BP, and the measurement of fasted glucose, insulin, adiponectin, insulin-like growth factor-I, and apolipoproteins. The trial registration number for Current Controlled Trials is ISRCTN37687716 and that for ClinicalTrials.gov is NCT01561612. Proposals for collaboration are welcome, and enquires about PROBIT should be made to an executive group of the study steering committee (M.S.K., R.M.M., and E.O.). More information, including information about how to access the trial data, data collection documents, and bibliography, is available at the trial website (http://www.bristol.ac.uk/social-community-medicine/projects/probit/).

Optimal duration of exclusive breastfeeding

BACKGROUND

Although the health benefits of breastfeeding are widely acknowledged, opinions and recommendations are strongly divided on the optimal duration of exclusive breastfeeding. Since 2001, the World Health Organization has recommended exclusive breastfeeding for six months. Much of the recent debate in developed countries has centred on the micronutrient adequacy, as well as the existence and magnitude of health benefits, of this practice.

OBJECTIVES

To assess the effects on child health, growth, and development, and on maternal health, of exclusive breastfeeding for six months versus exclusive breastfeeding for three to four months with mixed breastfeeding (introduction of complementary liquid or solid foods with continued breastfeeding) thereafter through six months.

SEARCH METHODS

We searched The Cochrane Library (2011, Issue 6), MEDLINE (1 January 2007 to 14 June 2011), EMBASE (1 January 2007 to 14 June 2011), CINAHL (1 January 2007 to 14 June 2011), BIOSIS (1 January 2007 to 14 June 2011), African Index Medicus (searched 15 June 2011), Index Medicus for the WHO Eastern Mediterranean Region (IMEMR) (searched 15 June 2011), LILACS (Latin American and Caribbean Health Sciences) (searched 15 June 2011). We also contacted experts in the field.The search for the first version of the review in 2000 yielded a total of 2668 unique citations. Contacts with experts in the field yielded additional published and unpublished studies. The updated literature review in December 2006 yielded 835 additional unique citations.

SELECTION CRITERIA

We selected all internally-controlled clinical trials and observational studies comparing child or maternal health outcomes with exclusive breastfeeding for six or more months versus exclusive breastfeeding for at least three to four months with continued mixed breastfeeding until at least six months. Studies were stratified according to study design (controlled trials versus observational studies), provenance (developing versus developed countries), and timing of compared feeding groups (three to seven months versus later).

DATA COLLECTION AND ANALYSIS

We independently assessed study quality and extracted data.

MAIN RESULTS

We identified 23 independent studies meeting the selection criteria: 11 from developing countries (two of which were controlled trials in Honduras) and 12 from developed countries (all observational studies). Definitions of exclusive breastfeeding varied considerably across studies. Neither the trials nor the observational studies suggest that infants who continue to be exclusively breastfed for six months show deficits in weight or length gain, although larger sample sizes would be required to rule out modest differences in risk of undernutrition. In developing-country settings where newborn iron stores may be suboptimal, the evidence suggests that exclusive breastfeeding without iron supplementation through six months may compromise hematologic status. Based on the Belarusian study, six months of exclusive breastfeeding confers no benefit (versus three months of exclusive breastfeeding followed by continued partial breastfeeding through six months) on height, weight, body mass index, dental caries, cognitive ability, or behaviour at 6.5 years of age. Based on studies from Belarus, Iran, and Nigeria, however, infants who continue exclusive breastfeeding for six months or more appear to have a significantly reduced risk of gastrointestinal and (in the Iranian and Nigerian studies) respiratory infection. No significant reduction in risk of atopic eczema, asthma, or other atopic outcomes has been demonstrated in studies from Finland, Australia, and Belarus. Data from the two Honduran trials and from observational studies from Bangladesh and Senegal suggest that exclusive breastfeeding through six months is associated with delayed resumption of menses and, in the Honduran trials, more rapid postpartum weight loss in the mother.

AUTHORS' CONCLUSIONS

Infants who are exclusively breastfed for six months experience less morbidity from gastrointestinal infection than those who are partially breastfed as of three or four months, and no deficits have been demonstrated in growth among infants from either developing or developed countries who are exclusively breastfed for six months or longer. Moreover, the mothers of such infants have more prolonged lactational amenorrhea. Although infants should still be managed individually so that insufficient growth or other adverse outcomes are not ignored and appropriate interventions are provided, the available evidence demonstrates no apparent risks in recommending, as a general policy, exclusive breastfeeding for the first six months of life in both developing and developed-country settings.

Sociodemographic determinants of early weaning: a Finnish birth cohort study in infants with human leucocyte antigen-conferred susceptibility to type 1 diabetes

OBJECTIVE

To assess the most important sociodemographic determinants of age at introduction of complementary foods in infancy.

DESIGN

A prospective birth cohort with increased risk of type 1 diabetes, recruited between 1996 and 2004. The families completed at home a follow-up form on the age at introduction of new foods and, for each clinic visit, a structured dietary questionnaire with 3 d food records.

SETTING

Data from the Type 1 Diabetes Prediction and Prevention (DIPP) Project, Finland.

SUBJECTS

A cohort of 5991 infants (77 % of those invited) belonging to the DIPP Nutrition Study.

RESULTS

Sixty-three per cent of the infants were introduced to complementary foods, including infant formula, before the age of 4 months. The median age at introduction of infant formula was 1·5 months (range 0-18 months) and that of the first other complementary food 3·5 months (range 0·7-8 months). All sociodemographic and lifestyle factors studied were associated with the age at introduction of infant formula and/or first other complementary food. Female sex of the infant, being born in the southern region of Finland, living in a rural municipality, the presence of siblings, the mother or the father being a high-school graduate, high maternal professional education and maternal non-smoking during pregnancy predicted later introduction of complementary foods.

CONCLUSIONS

Compliance was relatively poor with the current recommendations for the age of introducing complementary foods. Small-sized young families with less well-educated parents were most prone to introduce complementary foods early.

Do complementary feeding practices predict the later risk of obesity?

PURPOSE OF REVIEW

Obesity is a multifaceted public health problem, which should be addressed with an all-encompassing approach. Recent research has asked questions that link specific infant nutritional risks to childhood obesity. This article brings recent research in the area of complimentary feeding practices to light and summarizes the research on its consequent impact on obesity risk.

RECENT FINDINGS

The article will discuss the current conflicting evidence on the relationship between the timing of introduction of complimentary foods and later obesity risk. It will summarize recent findings on the impact that complimentary feeding has on food preferences, growth and weight gain during the first year of life.

SUMMARY

In industrialized countries complementary feeding has no major impact on obesity. However, there is some evidence that the age at introduction of complementary foods has some effect on growth in infancy and that effects might be more pronounced in formula-fed children. The focus of research should be shifted from the timing of the introduction of complementary feeding to the quality and quantity of foods being offered and their consequent impact on weight gain and obesity risk. More research should be conducted on the relationship of primary nutrition to appetite regulation, satiety and food acceptance.