Infant growth and body composition from birth to 24 months: are infants developing the same?

From Mother-Fetus Dyad to Mother-Milk-Infant Triad: Sex Differences in Macronutrient Composition of Breast Milk

Background: The composition of breast milk is influenced by a variety of factors, including maternal anthropometric characteristics, dietary and lifestyle habits, and lactation and feeding parameters. Emerging evidence also suggests that an infant's sex may play a role in shaping breast milk composition. Objective: This study aims to investigate the macronutrient composition of early breast milk up to 3 months postpartum, with a particular focus on potential differences related to the infant's sex. Methods: A total of 102 breast milk samples were collected at four time points across three lactation stages, representing colostrum, transitional, and mature milk, from a cohort consisting of 51 consenting mothers of Mediterranean origin who met the inclusion criteria. The samples were analyzed using mid-infrared spectroscopy to determine their macronutrient composition. Results: Colostrum from mothers of male infants contained approximately 60% higher levels of nitrogenous compounds, crude protein, true protein, and non-protein nitrogen compared to colostrum from mothers of female infants. Transitional milk for female infants contained higher fat, total solids, and energy. No significant differences in macronutrient composition were observed in mature milk between the sexes. For both sexes, colostrum contained more nitrogenous compounds and fewer total solids than mature milk. Male colostrum had lower carbohydrate levels compared to the later stages of lactation, while female samples showed no significant changes. Strong positive correlations between fat and crude protein were found for both sexes during the transitional and mature milk stages. In male colostrum, all macronutrients were interrelated. Conclusions: The observed differences in the composition of colostrum and transitional breast milk for male and female neonates suggest potential sex-specific nutritional adaptations during early lactation. These findings may have implications for personalized infant nutrition strategies in cases where breast feeding is hampered, as well as for understanding early neonatal adaptations.

Exploring Infant Size and Body Composition at 18 Months: An Ambidirectional Peri-Urban South African Cohort Study

The first 1000 days of life lay the foundations for subsequent growth. This ambidirectional study, including prenatal, perinatal and postnatal factors, aimed to identify exposure variables affecting body size and composition and corresponding Z-score outcomes at age 18 months in infants born to women at low risk of adverse pregnancy outcomes in a peri-urban area of South Africa. Prenatal factors (maternal age, HIV status, anthropometry, parity, food insecurity and umbilical artery resistance index Z-score (UmA-RIAZ) as a measure of placental function, with higher UmA-RIAZ indicating poorer placental function); perinatal factors (infant sex, gestational age and birth anthropometry) and postnatal factors (infant feeding) were included as exposure variables, with infant anthropometry and body composition at 18 months as outcomes. Simple linear regression analysis was used to investigate associations between exposure variables and infant outcomes, and variables with p < 0.10 were included in the subsequent multiple regression analyses. Multiple regression analysis showed that higher UmA-RIAZ predicted lower birthweight [-0.11 kg (95% CI: -0.17, -0.04 kg)], birthweight-for-age Z-score [-0.24 (95% CI: -0.39, -0.09)] and 18-month infant length [-0.9 cm (95% CI: -1.4, -0.4 cm)] and length-for-age Z-score [-0.28 (95% CI: -0.45, -0.11)]. Maternal HIV infection predicted reduced 18-month infant length-for-age Z-score [-0.46 (95% CI: -0.83, -0.09)]. Household food insecurity predicted reduced fat-free mass-for-age Z-score at 18 months [-0.27 (95% CI: -0.51, -0.03)]. Infant anthropometry and body composition outcomes, therefore, are greatly affected by pre- and postnatal nutrition-related factors, such as placental insufficiency in utero and household food insecurity, with long-term consequences including stunting, which impact the individual, future generations and society.

Anthropometric prediction models of body composition in 3 to 24month old infants: a multicenter international study

BACKGROUND

Accurate assessment of body composition during infancy is an important marker of early growth. This study aimed to develop anthropometric models to predict body composition in 3-24-month-old infants from diverse socioeconomic settings and ethnic groups.

METHODS

An observational, longitudinal, prospective, multi-country study of infants from 3 to 24 months with body composition assessed at three monthly intervals using deuterium dilution (DD) and anthropometry. Linear mixed modelling was utilized to generate sex-specific fat mass (FM) and fat-free mass (FFM) prediction equations, using length(m), weight-for-length (kg/m), triceps and subscapular skinfolds and South Asian ethnicity as variables. The study sample consisted of 1896 (942 measurements from 310 girls) training data sets, 941 (441 measurements from 154 girls) validation data sets of 3-24 months from Brazil, Pakistan, South Africa and Sri Lanka. The external validation group (test) comprised 349 measurements from 250 (185 from 124 girls) infants 3-6 months of age from South Africa, Australia and India.

RESULTS

Sex-specific equations for three age categories (3-9 months; 10-18 months; 19-24 months) were developed, validated on same population and externally validated. Root mean squared error (RMSE) was similar between training, validation and test data for assessment of FM and FFM in boys and in girls. RMSPE and mean absolute percentage error (MAPE) were higher in validation compared to test data for predicting FM, however, in the assessment of FFM, both measures were lower in validation data. RMSE for test data from South Africa (M/F-0.46/0.45 kg) showed good agreement with validation data for assessment of FFM compared to Australia (M/F-0.51/0.33 kg) and India(M/F-0.77/0.80 kg).

CONCLUSIONS

Anthropometry-based FFM prediction equations provide acceptable results. Assessments based on equations developed on similar populations are more applicable than those developed from a different population.

How did the use of the social marketing approach in Egyptian communities succeed in improving breastfeeding practices and infants' growth?

INTRODUCTION

Improving breastfeeding practices does not always link to interventions relying only on improving nutrition awareness and education but needs cultural and behavioral insights .

AIM

This study aimed to evaluate the changes in core breastfeeding indicators as a result of the use of social marketing (SM) approach for improving breastfeeding practices of Egyptian women and the physical growth of infants aged 6 to 12 months. The core breastfeeding indicators were: Early initiation of breastfeeding within one hour of birth, Predominant and exclusive breastfeeding to 6 months (EBF), Bottle feeding with formula, continued breastfeeding to 1 and 2 years, and responsiveness to cues of hunger and satiety.

METHODS

A quasi-experimental longitudinal study with a posttest-only control design was done over 3 years in three phases; the first was in-depth interviews and formative research followed by health education and counseling interventions and ended by measuring the outcome. Motivating mothers' voluntary behaviors toward breastfeeding promotion "feeding your baby like a baby" was done using SM principles: product, price, place, and promotion. The interventions targeted 646 pregnant women in their last trimester and delivered mothers and 1454 women in their childbearing period. The statistical analysis was done by using SPSS program, version 26.

RESULTS

Most mothers showed significantly increased awareness about the benefits of breastfeeding and became interested in breastfeeding their children outside the house using the breastfeeding cover (Gawn) (p < 0.05). Breastfeeding initiation, exclusive breastfeeding under 6 months, frequency of breastfeeding per day, and percentage of children who continued breastfeeding till 2 years, were significantly increased (from 30%, 23%, 56%, and 32% to 62%, 47.3%, 69%, and 43.5% respectively). The girls who recorded underweight results over boys during the first year of life were significantly improved (p < 0.01) after the intervention (from 52.1% to 18.8% respectively). At the same time, girls found to be obese before the intervention (15.6%) became no longer obese.

CONCLUSIONS

Improvement for the majority of the key breastfeeding indicators and physical growth of infants indicates that raising a healthy generation should start by promoting breastfeeding practices that are respectable to societal norms.