| Objectives:The objectives were to explore whether the body composition of children at age 3-5 y was related to ever breastfeeding,the duration of breastfeeding(never,<4 months,4-<6 months,6-<12 months,12-<24 months and≥24 months),and to timing of introducing complementary foods(≤5-month-old,6-month-old and≥7-month-old)in infants and young children.Methods:This was a cross-sectional study and data were from Chinese nutrition and health system survey and application for children aged 0-18 years project.We enrolled children who have completed the questionnaire survey,physical and body composition measurement from the project as of January 2021.Also,we excluded those whose age was under 3 years or more than 5 years old,multiple pregnancy,and those with missing feeding information in the questionnaire and missing physical and body composition information.A total of 2008 subjects were included in the study.The survey sites were Taigu County of Jinzhong,Shanxi Province,Dongchang District of Tonghu and Yongji County,Jilin Province,Qingshan Lake District of Nanchang,Jiangxi Province,Yuelu District of Changsha,Hunan Province,and Longchuan County of Heyuan,Guangdong Province.The study was approved by the Ethics Review Board of the National Institute for Nutrition and Health,Chinese Center for Disease Control and Prevention(Number:2019-009).Written informed consent was obtained from each child’s caregivers before the survey.The standardized questionnaires were used to retrospectively collect the information about duration of breastfeeding,timing for introducing complementary foods and potential confounders through face-to-face interviews.Bioelectrical impedance analysis(InBody770)was used to measure the current body composition of children.The main outcomes of the study were total body composition indicators(including fat free mass,fat free mass index,total body water,skeletal muscle mass,bone mineral content.and total body fat mass,body fat index and percentage of body fat)and segment composition indicators(including arm/leg/trunk fat free mass,trunk to extremities fat mass ratio,and visceral fat area).Exposure variables are breastfeeding(never,ever),duration of breastfeeding(never,<4 months old,4-<6 months old,6-<12 months old,12-<24 months old,and≥24 months old),timing for introducing complementary foods(≤5 months old,6 months old and≥7 months old).According to age stratification,for normal distribution data or logarithmic transformation of normal data,a multivariate linear regression model to was used to calculate the mean,difference,and 95%CI of the outcomes after adjusting for gender and other confounders.Ordinal Logistic regression was used to calculate OR value and 95%CI of the ratio of trunk to extremities fat mass.After adjusting for possible confounders such as gender,birth weight,survey sites,HAZ/WAZ,night sleep time,middle and high-level physical activity time,eating behavior score,balanced diet index score,parental BMI and education level,relationship between breastfeeding,different breastfeeding durations and different timing of introducing complementary foods and the body composition of preschool children was examined.Results:Finally,a number of 2008 children aged 3 to 5 years were included in this study,1,008 were boys,accounting for 50.20%and 1,000 were girls,accounting for 49.80%.The number of children aged 3,4 and 5 years old were 642,700 and 666,respectively.There are 1,102 children in urban areas and 906 in rural areas,and 1106 in the northern areas and 902 in the southern areas.The prevalence of breastfeeding of the subjects was 89.19%.Among them,26.26%were weaned before 6 months of age,28.38%were weaned at 6-<12 months,41.43%were weaned at 12-<24 months,and 3.94%.Breastfeeding of children continues until 24 months of age and above.Children≤5 months of age,6 months of age and≥7 months of age adding complementary food accounted for 38.45%,38.72%,and 22.83%,respectively.The mean height of children was 107.08±7.43 cm,BMI is 15.36(14.56,16.30)kg/m2.The weight-for-age Z-score(WAZ)was 0.22 ± 1.05,height-for-age Z Z-score(HAZ)was 0.20 ± 0.98,BMI-for-age Z-score(BAZ)was 0.13 ± 1.10,and weight-for-height Z-score(WHZ)was 0.10±1.00.The prevalence of stunting,wasting,underweight and overweight/obesity was 1.10%,1.69%,0.85%,and 4.08%,respectively.1.Relationship between breastfeeding and fat free mass indicators of 3-5 years children.For children aged 3 years old,after adjusting gender,birth weight,survey sites,HAZ(fat free mass index was not adjusted by HAZ),night sleep time,middle and high-level physical activity time,eating behavior score,balanced diet index score,parental BMI and education level,in terms of total body composition,the fat free mass(12.84 kg vs 12.52 kg,F=5.91,P=0.015),total body water(9.53 kg vs 9.27 kg,F=6.51,P=0.011)and skeletal muscle mass(5.64 kg vs 5.44 kg,F=6.20,P=0.013)of ever-breastfeeding infants were higher than those of never-breastfeeding,and the fat free mass index and bone mineral content of the two groups were not statistically significant(P>0.05).In terms of segmental body composition,ever-breastfeeding group had higher trunk fat free mass than never-breastfeeding group(F=4.61,P=0.032).For children aged 4 years old,after adjusting for potential confounders,in terms of overall body composition,the fat free mass(14.31kg vs 14.64kg,F=3.92,P=0.048)and skeletal muscle mass(6.47 kg vs 6.68 kg.F=4.17.P=0.042)of ever-breastfeeding group were lower than those of never-breastfeeding.The differences of the fat free mass index,total body water and bone mineral content between ever-breastfeeding and never-breastfeeding groups were not statistically significant(P>0.05).In terms of segment body composition,the fat free mass of the leg limbs of ever-breastfeeding group was lower than those of never-breastfeeding(1.65 kg vs 1.73 kg,F=4.68,P=0.031).Breastfeeding or not is not related to the fat free mass of the arm limbs and trunk of children.For children aged 5 years old,after adjusting for potential confounders,there was no statistically significant difference in the fat free mass indicators between ever-breastfeeding and ever-breastfeeding groups(P>0.05).2.Relationship between the duration of breastfeeding and the fat free mass indicators of children aged 3 to 5 years.For children aged 3 and 4 years old,after adjusting for potential confounders,there was no statistically significant difference in the fat free mass indicators among children with different breastfeeding duration(P>0.05).For children aged 5 years old,in terms of total body composition,the overall difference of the fat free mass(F=4.09,P=0.001),total body water(F=3.74,P=0.003)and skeletal muscle mass(F=4.07,P=0.001)of children with different breastfeeding duration was statistically significant.But there was no statistically significant difference between the different breastfeeding duration groups and the reference group(never breastfeeding).There were no significant differences in fat-free body mass index and bone mineral content among children with different breastfeeding durations(P>0.05).In terms of segment body composition,the overall difference in arm(F=2.34,P=0.041),leg(F=3.71,P=0.003)and trunk fat free mass(F=3.61,P=0.003)of children with different breastfeeding duration was statistically significant,but there was no statistically significant difference between the different breastfeeding duration groups and the reference group(never breastfeeding).3.The relationship between timing for introducing of complementary foods and fat free mass indicators of children aged 3 to 5 years.For children aged 3 years,after adjusting for potential confounders,in terms of total body composition,the difference of fat free mass(F=4.42,P=0.013),total body water(F=3.93,P=0.020)and skeletal muscle mass(F=3.80,P=0.023)among children with different timing for introducing of complementary foods was statistically significant.Among them,the fat free mass(mean difference(95%CI):-0.23(-0.45,-0.02))and total body water(mean difference(95%CI):-0.16(-0.33,-0.002))of children introducing complementary foods during 6 months of age was lower than those introducing complementary foods at≤5 months of age.There was no significant difference in the fat free mass index and bone mineral content among different timing for introducing of complementary foods groups.In terms of segment body composition,there were no statistically significant differences in segment fat free mass indicators in children with different timing for introducing of complementary foods.For children aged 4 years,after adjusting for potential confounders,there was no statistically significant difference in the fat free mass indicators of children with different timing for introducing of complementary foods(P>0.05).For children aged 5 years,after adjusting for potential confounders,in terms of total body composition,the difference of fat free mass(F=5.40,P=0.005),total body water(F=5.68,P=0.004)and skeletal muscle mass(F=5.47,P=0.005)of children with different timing for introducing of complementary foods was statistically significant.Among them,the fat free mass(mean difference(95%CI):0.39(0.08,0.70)),body water content(mean difference(95%CI):0.32(0.08,0.56))and skeletal muscle mass(mean difference(95%CI):0.26(0.06,0.46))of children introducing complementary foods at≥7 months of age was higher than those of children introducing complementary foods at≤5 months of age.There was no statistically significant difference in fat free mass index and bone mineral content among children with different timing for introducing of complementary foods groups(P>0.05).In terms of segment body composition,there was no statistically significant difference in the arm fat free mass of children with different timing for introducing of complementary foods groups.The leg(F=5.51,P=0.004)and trunk fat free mass(F=4.41,P=0.013)was increased with the delay in introducing complementary foods.Among them,the leg(mean difference(95%CI):0.06(0.03,0.18))and trunk fat free mass(mean difference(95%CI):0.26(0.05,0.47)))of children introducing complementary foods ≥7 months of age was higher than those≤5 months of age.4.Relationship between breastfeeding,breastfeeding duration and the timing for introducing complementary foods and fat mass indicatorsAfter adjusting for potential confounders,there was no statistically significant difference in body fat indicators among different groups of breastfeeding,breastfeeding duration and timing for introducing complementary foods for children aged 3-5 years old.Conclusion:1.Breastfeeding or not,breastfeeding duration and timing for introducing complementary foods in infants and young children may be introducing with some of the fat free mass indicators of children aged 3 to 5 years,but not associated with body fat mass indicators such as body fat mass,fat mass index and percentage of body fat.2.For children of different ages,the relationship between breastfeeding in infants and young children and some fat free mass indicators may be different.The fat free mass,total body water,and skeletal muscle mass of ever-breastfeeding groups at the age of 3 were higher than those of never-breastfeeding.At the age of 4,the fat free mass and skeletal muscle mass of ever-breastfeeding group were lower than those of never-breastfeeding.For 5 years old children,there was no relation between the body composition indicators and breastfeeding status.3.For children of different ages,the relationship between timing for introducing complementary foods and some fat free mass indicators may be inconsistent.For 3 years old children,the fat free mass of children introducing complementary foods at≤5 months of age was greater than those at 6 months of age.For 4 years old children,the timing for introducing complementary foods was not associated with their fat free mass.For 5 years old children,the fat free mass of children introducing complementary foods at≤5 months of age was less than those at≥7 months of age. |
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