Resistin and leptin in breast milk and infants in early life.

BACKGROUND: The role of adipokines in early life is considered an emerging topic issue in nutritional researches. AIMS: To evaluate serum resistin and leptin concentrations and their relations in infants and in breast milk. STUDY DESIGN: We enrolled 41 term, AGA, healthy infants, of which 23 exclusively breast-fed (BF) and 18 formula-fed (FF), aged less than 6 months. Breast milk (BM) samples were collected from 23 breastfeeding mothers of the infants enrolled. Resistin concentration in serum and BM was determined by ELISA test (Human-Resistin-ELISA, Mediagnost, Reutlingen, Germany). Leptin concentration was determined by Radioimmunoassay method (LEP-R40, Mediagnost, Reutlingen, Germany). Infants weight, length and body mass index were measured. We used Mann-Whitney test. Spearman correlation was applied. Statistical significance was set at p<0.05. Data are reported as median and interquartile range (IR). RESULTS: Infants serum resistin concentration was 9.30 (5.02) ng/ml. Breast milk resistin concentration (n=23) was 0.18 (0.44) ng/ml. Leptin concentration was 3.04 (3.68) ng/ml in infants serum and in BM was 2.34 (5.73) ng/ml. Serum resistin concentrations in BF infants correlated positively with BM resistin (r=0.636, p=0.035). We have shown a positive correlation between resistin and leptin in total group of infants (r=0.44, p=0.05), confirmed in breastfed subjects (r=0.65, p=0.02). No correlations were found between serum hormones and anthropometric parameters of infants. CONCLUSION: Our findings show interestingly a positive correlation between resistin concentrations in BF infants serum and in BM and between resistin and leptin in infants.

Antagonistic effect of Lactobacillus strains against gas-producing coliforms isolated from colicky infants.

BACKGROUND: Infantile colic is a common disturb within the first 3 months of life, nevertheless the pathogenesis is incompletely understood and treatment remains an open issue. Intestinal gas production is thought to be one of the causes of abdominal discomfort in infants suffering from colic. However, data about the role of the amount of gas produced by infants' colonic microbiota and the correlation with the onset of colic symptoms are scanty. The benefit of supplementation with lactobacilli been recently reported but the mechanisms by which they exert their effects have not yet been fully defined. This study was performed to evaluate the interaction between Lactobacillus spp. strains and gas-forming coliforms isolated from stools of colicky infants. RESULTS: Strains of coliforms were isolated from stools of 45 colicky and 42 control breastfed infants in McConkey Agar and identified using PCR with species-specific primers, and the BBL™ Enterotube™ II system for Enterobacteriaceae. Gas-forming capability of coliforms was assessed in liquid cultures containing lactose as sole carbon source. The average count of total coliforms in colicky infants was significantly higher than controls: 5.98 (2.00-8.76) log10 vs 3.90 (2.50-7.10) CFU/g of faeces (p = 0.015). The following strains were identified: Escherichia coli, Klebsiella pneumoniae, Klebsiella oxytoca, Enterobacter aerogenes, Enterobacter cloacae and Enterococcus faecalis. Then, 27 Lactobacillus strains were tested for their antagonistic effect against coliforms both by halo-forming method and in liquid co-cultures. Lactobacillus delbrueckii subsp. delbrueckii DSM 20074 and L. plantarum MB 456 were able to inhibit all coliforms strains (halo-forming method), also in liquid co-cultures, thus demonstrating an antagonistic activity. CONCLUSIONS: This study shows that two out of 27 strains of Lactobacillus examined possess an antimicrobial effect against six species of gas-forming coliforms isolated from colicky infants. Our findings may stimulate new researches to identify which Lactobacillus strains can improve colicky symptoms by acting on coliforms gut colonization.

Breast milk hormones and regulation of glucose homeostasis.

Growing evidence suggests that a complex relationship exists between the central nervous system and peripheral organs involved in energy homeostasis. It consists in the balance between food intake and energy expenditure and includes the regulation of nutrient levels in storage organs, as well as in blood, in particular blood glucose. Therefore, food intake, energy expenditure, and glucose homeostasis are strictly connected to each other. Several hormones, such as leptin, adiponectin, resistin, and ghrelin, are involved in this complex regulation. These hormones play a role in the regulation of glucose metabolism and are involved in the development of obesity, diabetes, and metabolic syndrome. Recently, their presence in breast milk has been detected, suggesting that they may be involved in the regulation of growth in early infancy and could influence the programming of energy balance later in life. This paper focuses on hormones present in breast milk and their role in glucose homeostasis.

Assay of ghrelin concentration in infant formulas and breast milk.

AIM: To test if total ghrelin is present in infant formulas. METHODS: Using a radioimmunoassay, we measured total ghrelin concentrations in 19 samples of commercial infant formulas and in 20 samples of human milk. We also determined ghrelin concentration in the serum of infants and lactating mothers. RESULTS: Ghrelin concentrations were significantly higher in artificial milk (2007.1 ± 1725.36 pg/mL) than in human milk (828.17 ± 323.32 pg/mL) (P = 0.005). The mean ghrelin concentration in infant serum (n = 56) was 1115.86 ± 42.89 pg/mL, and was significantly higher (P = 0.023) in formula-fed infants (1247.93 ± 328.07 pg/mL) than in breast-fed infants (1045.7 ± 263.38 pg/mL). The mean serum ghrelin concentration (mean ± SD) in lactating mothers (n = 20) was 1319.18 ± 140.18 pg/mL. CONCLUSION: This study provides evidence that total ghrelin is present in infant formulas. This finding raises diverse questions regarding the uptake, absorption and metabolic effects of this hormone.

Lactobacillus reuteri DSM 17938 in infantile colic: a randomized, double-blind, placebo-controlled trial.

OBJECTIVE: To test the efficacy of Lactobacillus reuteri on infantile colic and to evaluate its relationship to the gut microbiota. STUDY DESIGN: Fifty exclusively breastfed colicky infants, diagnosed according to modified Wessel's criteria, were randomly assigned to receive either L reuteri DSM 17 938 (10(8) colony-forming units) or placebo daily for 21 days. Parental questionnaires monitored daily crying time and adverse effects. Stool samples were collected for microbiologic analysis. RESULTS: Forty-six infants (L reuteri group: 25; placebo group: 21) completed the trial. Daily crying times in minutes/day (median [interquartile range]) were 370 (120) vs 300 (150) (P=.127) on day 0 and 35.0 (85) vs 90.0 (148) (P=.022) on day 21, in the L reuteri and placebo groups, respectively. Responders (50% reduction in crying time from baseline) were significantly higher in the L reuteri group versus placebo group on days 7 (20 vs 8; P=.006), 14 (24 vs 13; P=.007), and 21 (24 vs 15; P=.036). During the study, there was a significant increase in fecal lactobacilli (P=.002) and a reduction in fecal Escherichia coli and ammonia in the L reuteri group only (P=.001). There were no differences in weight gain, stooling frequency, or incidence of constipation or regurgitation between groups, and no adverse events related to the supplementation were observed. CONCLUSION: L. reuteri DSM 17 938 at a dose of 10(8) colony-forming units per day in early breastfed infants improved symptoms of infantile colic and was well tolerated and safe. Gut microbiota changes induced by the probiotic could be involved in the observed clinical improvement.

High faecal calprotectin levels in healthy, exclusively breast-fed infants.

BACKGROUND: Faecal calprotectin has been proposed as a sensitive marker for gastrointestinal inflammation in children and adults. High levels have been reported in healthy newborns and during the first months of life; the effect of the kind of feeding on the calprotectin concentration in stools is controversial. OBJECTIVE: To evaluate faecal calprotectin values in healthy, exclusively breast-fed (BF) or formula-fed (FF) infants. METHODS: Stool samples were obtained from 74 healthy infants (39 exclusively BF and 35 exclusively FF) with a median age of 51 days (range 13-90). Exclusion criteria were acute infections and treatment with anti-inflammatory drugs. Stool samples were stored at -20 degrees C until they were analysed, and the faecal calprotectin concentration was detected using a commercial quantitative enzyme-linked immunoassay (Calprest; Eurospital SpA, Trieste, Italy). RESULTS: The median faecal calprotectin concentration was significantly higher in BF infants (555.00 microg/g, range 122.5-2,000.0 microg/g) than in FF ones (206.60 mug/g, range 31.2-797.6 microg/g) (p < 0.001). We observed a significantly higher median stool frequency in BF infants than in FF ones (p < 0.001), but multiple regression analysis (independent variables: kind of feeding and stool frequency; dependent variable: calprotectin) showed a significant coefficient for the kind of feeding, but not for stool frequency (p = 0.937). CONCLUSIONS: Our findings show that the kind of feeding influences the faecal calprotectin concentration, with higher values in healthy exclusively BF infants than in FF ones. Our study does not allow us to clearly identify the reason for our finding; this could be due to hormones (such as ghrelin and leptin), cytokines and other immunostimulating and growth factors (such as epidermal growth factor and granulocyte colony-stimulating factor) in human milk, which contribute to the development of the gastrointestinal immune system. Further investigations are needed to better clarify the mechanism underlying the relationship between feeding and faecal calprotectin levels in young infants.

Can hormones contained in mothers' milk account for the beneficial effect of breast-feeding on obesity in children?

Nutrition and growth during infancy are an emerging issue because of their potential link to metabolic health disorders in later life. Moreover, prolonged breast-feeding appears to be associated with a lower risk of obesity than formula feeding. Human milk is a source of various hormones and growth factors, namely adipokines (leptin and adiponectin), ghrelin, resistin and obestatin, which are involved in food intake regulation and energy balance. These compounds are either not found in commercial milk formulas or their presence is still controversial. Diet-related differences during infancy in serum levels of factors involved in energy metabolism might explain anthropometric differences and also differences in dietary habits between breast-fed (BF) and formula-fed (FF) infants later in life, and may thus have long-term health consequences. In this context, the recent finding of higher leptin levels and lower ghrelin levels in BF than in FF infants suggests that differences in hormonal values together with different protein intake could account for the differences in growth between BF and FF infants both during infancy and later in life. In this review, we examine the data related to hormones contained in mothers' milk and their potential protective effect on subsequent obesity and metabolic-related disorders.

Breast milk hormones and their protective effect on obesity.

Data accumulated over recent years have significantly advanced our understanding of growth factors, cytokines, and hormones in breast milk. Here we deal with leptin, adiponectin, IGF-I, ghrelin, and the more recently discovered hormones, obestatin, and resistin, which are present in breast milk and involved in food intake regulation and energy balance. Little is known about these compounds in infant milk formulas. Nutrition in infancy has been implicated in the long-term tendency to obesity, and a longer duration of breastfeeding appears to protect against its development. Diet-related differences in serum leptin and ghrelin values in infancy might explain anthropometric differences and differences in dietary habits between breast-fed and formula-fed infants also later in life. However, there are still gaps in our understanding of how hormones present in breast milk affect children. Here we examine the data related to hormones contained in mother's milk and their potential protective effect on subsequent obesity.

Looking for a relation between serum leptin concentration and body composition parameters in healthy term infants in the first 6 months of life.

We carried out a cross-sectional study of 115 healthy infants, younger than 6 months old, exclusively breast-fed or formula-fed, to investigate correlations between circulating leptin concentrations and body composition measurements. Serum leptin was evaluated with radioimmunoassay, and body composition with bioelectrical impedance analysis. Multiple regression analysis showed a relationship between serum leptin and body mass index in the entire study population (P = 0.042). There was a significant negative relationship between serum leptin and phase angle (P = 0.006) in formula-fed infants. Serum leptin was positively related to subscapular skinfold thickness (P = 0.055) and negatively to reactance (P = 0.057) only in formula-fed infants, although the differences were just below significance. Serum leptin concentration was higher in breast-fed infants (P = 0.002), and was not correlated with body composition parameters. This study indicates that there is a relation between leptin and infant body composition in the first months of life, although the link needs to be explored further.

Serum ghrelin concentration, fasting time and feeding in infants.

BACKGROUND: Data on hormonal feeding control in infants in the first months of life according to the kind of feeding are scanty. AIM: To evaluate whether serum ghrelin could be involved in feeding behaviour control of breast-fed (BF) and formula fed (FF) infants. METHODS: We studied 50 AGA healthy term infants aged 1-6 months of age. Serum ghrelin concentration was determined by RIA. Fasting time (measured as the difference between the time of the last meal and the time of blood collection) and number of meals were recorded. RESULTS: A positive correlation between serum ghrelin levels and fasting time emerged in FF infants (r = 0.752; p <0.001) but not in BF infants (r = 0.345; p = 0.072). CONCLUSIONS: Circulating ghrelin concentration correlates positively with fasting time in FF infants; these infants have higher serum ghrelin concentration, longer fasting time and fewer meals than BF infants. These observations suggest a possible influence of early feeding on mechanisms regulating satiety and feeding behaviour.

Lactobacillus reuteri (American Type Culture Collection Strain 55730) versus simethicone in the treatment of infantile colic: a prospective randomized study.

OBJECTIVE: The goal was to test the hypothesis that oral administration of Lactobacillus reuteri in a prospective randomized study would improve symptoms of infantile colic. METHODS: Ninety breastfed colicky infants were assigned randomly to receive either the probiotic L. reuteri (10(8) live bacteria per day) or simethicone (60 mg/day) each day for 28 days. The mothers avoided cow's milk in their diet. Parents monitored daily crying times and adverse effects by using a questionnaire. RESULTS: Eighty-three infants completed the trial: 41 in the probiotic group and 42 in the simethicone group. The infants were similar regarding gestational age, birth weight, gender, and crying time at baseline. Daily median crying times in the probiotic and simethicone groups were 159 minutes/day and 177 minutes/day, respectively, on the seventh day and 51 minutes/day and 145 minutes/day on the 28th day. On day 28, 39 patients (95%) were responders in the probiotic group and 3 patients (7%) were responders in the simethicone group. No adverse effects were reported. CONCLUSIONS: In our cohort, L. reuteri improved colicky symptoms in breastfed infants within 1 week of treatment, compared with simethicone, which suggests that probiotics may have a role in the treatment of infantile colic.

Ghrelin and motilin concentration in colicky infants.

AIM: To evaluate serum ghrelin and motilin concentration in infants with infantile colic. METHODS: A case-control study was conducted on fasting blood venous samples obtained from 18 infants with infantile colic and 20 healthy infants to measure ghrelin (RIA test) and motilin (RIA test). RESULTS: Colicky infants showed higher ghrelin serum levels (2534.2 +/- 600.0 pg/ml; ln 7.8 +/- 0.2) than controls (2126.1 +/- 281.3 pg/ml; ln 7.6 +/- 0.1) (p = 0.011). Serum motilin concentration was significantly higher in colicky infants (94.6 +/- 23.2 pmol/l) than in controls (64.1 +/- 30.1 pmol/l) (p = 0.001). Motilin concentrations were higher in formula-fed colicky infants (104.5 +/- 20.4 pmol/l) than in breastfed ones (82.2 +/- 21.3 pmol/l) (p = 0.038). CONCLUSION: Our finding shows that ghrelin and motilin concentrations are higher in infants with colic than in controls, supporting an organicistic aetiopathogenesis of this disorder. Furthermore, the role of ghrelin on gastrointestinal motility may open new doors to better understand the aetiology of infantile colic.

Maternal BMI and serum leptin concentration of infants in the first year of life.

AIM: To evaluate the relationship between serum leptin concentration in infants and infant and maternal BMI. METHODS: 75 healthy term infants aged 0-12 mo, 51 exclusively breastfed (BF) for at least 4 mo and 24 formula fed (FF), were included in a cross-sectional study. Weight, length and cranial circumference of infants and their mothers were measured, body mass index (BMI) was calculated using the formula weight (kg)/height (m2) and infant serum leptin concentration was determined. RESULTS: A significant positive correlation between infant serum leptin concentration and maternal BMI was observed in BF infants (r = 0.389, p = 0.005), confirmed in a multiple regression model adjusted for infant age and infant BMI (beta = 0.065, p = 0.006), but not in FF infants. As regards the first 4 mo of life, we have already observed a positive correlation between infant serum leptin concentration and maternal BMI in BF infants (beta = 0.113, p = 0.005), but not in FF infants. CONCLUSION: In BF infants, serum leptin concentration correlates positively with maternal BMI. Higher maternal BMI values might increase leptin levels in breast milk, and maternal adiposity could be involved in infant energy balance.

Phenotype resembling Donnai-Barrow syndrome in a patient with 9qter;16qter unbalanced translocation.

We describe a 3-year-old boy with complete agenesis of corpus callosum, developmental delay/mental retardation, anterior diaphragmatic hernia, Morgagni type, severe hypermetropia, and facial dysmorphism suggesting the diagnosis of Donnai-Barrow syndrome. Subtelomeric FISH analysis revealed a paternally-derived t(9;16) (q34.3;q24.3) translocation with partial 9q monosomy and partial 16q trisomy. As some facial features resemble the 9q emerging phenotype, we suggest the hypothesis that some patients with Donnai-Barrow syndrome might be abscribed to 9q terminal deletion.

Z-score of weight for age of infants with atopic dermatitis and cow's milk allergy fed with a rice-hydrolysate formula during the first two years of life.

BACKGROUND: Recently, rice-based formulas have been widely used in hypoallergenic diets, but data on nutritional values are scarce. AIM: To evaluate the growth of infants fed with a rice-based hydrolysate formula, compared to those infants fed with a soy formula or an extensively hydrolysed casein formula, in the first 2 y of life. METHODS: A total of 88 infants were enrolled between March 2002 and March 2004. Fifty-eight infants with atopic dermatitis (AD) and cow's milk allergy (CMA), confirmed by open challenge, were enrolled as study group: 15 were fed with a rice-based hydrolysate formula (RHF), 17 with a soy-based formula (SF) and 26 with an extensively hydrolysed casein formula (eHCF). Thirty infants with AD without cow's milk allergy were recruited as a control group (CG) and fed with a free diet. Weight was recorded on enrolment and at 3-monthly intervals in the first year of life, and at 6-monthly intervals in the second year. Infants were weighed naked, before feeding, by means of an electronic integrating scale. The z-scores of weight for age were calculated. STATISTICS: One-way analysis of variance and Student's t-test were used for statistical comparison. Significance was set at p<0.05. RESULTS: No significant differences between the RHF, SF and eHCF groups were observed for the z-score of weight for age during the first 2 y of life, but a significantly lower difference was seen in the RHF group compared to the control group in the intervals 9 mo-1 y (p=0.025) and 1-1.5 y (p=0.020) of age. In contrast, the SF and eHCF groups were comparable to the control group, but the eHCF group was significantly lower (p=0) in the first trimester of life. CONCLUSION: Even if our findings show no significant difference between RHF and control, low weight observed in infants fed with RHF raises doubts about the nutritional adequacy of rice-hydrolysate formulas.

Advances in the management of digestive problems during the first months of life.

UNLABELLED: A study was carried out on 168 full-term infants with digestive problems such as regurgitation and/or constipation to evaluate the efficacy of new infant formulas containing partially hydrolysed whey protein, modified vegetable oil with a high beta-palmitic acid content, prebiotic oligosaccharides and starch. Infants receiving the new formulas had an increase in stool frequency of 0.60 between day 1 and day 7 (95% CI 0.19-1.01; p=0.004) and 0.53 (95% CI 0.11-0.90; p=0.015) between day 7 and day 14. A reduction of 1.06 in the number of regurgitation episodes was reported between day 1 and day 7 (95% CI 0.24-1.88; p=0.012) and 1.31 (95% CI 0.42-2.21; p=0.005) between day 7 and day 14. CONCLUSION: A prebiotic mixture of galacto-/fructo-oligosaccharides with a high beta-palmitic acid content may reduce digestive problems and improve intestinal tolerance in infants during the first months of life.

A prospective 10-year study on children who had severe infantile colic.

AIM: To evaluate the association between infantile colic and gastrointestinal, allergic and psychological disorders in childhood. METHODS: A prospective study was conducted on 103 infants aged 31-87 d. After 10 y, between 2001 and 2003, the children were recalled and a paediatrician evaluated the selected disorders by anamnesis, medical examination, laboratory tests and parent interviews. RESULTS: Of the 103 infants enrolled, 96 completed the study. There was an association between infantile colic and recurrent abdominal pain (p=0.001) and allergic disorders: allergic rhinitis, conjunctivitis, asthmatic bronchitis, pollenosis, atopic eczema and food allergy (p<0.05). Sleep disorders, fussiness, aggressiveness and feelings of supremacy are more frequent in children who suffered from colic during early infancy (p<0.05). A family history of gastrointestinal diseases and atopic diseases was significantly higher in infants with colic than in controls (p<0.05). CONCLUSION: Susceptibility to recurrent abdominal pain, allergic and psychological disorders in childhood may be increased by infantile colic. Our findings confirm that severe infantile colic might be the early expression of some of the most common disorders in childhood.

Ghrelin, leptin and IGF-I levels in breast-fed and formula-fed infants in the first years of life.

AIM: To establish ghrelin, leptin and IGF-I serum levels in breastfed (BF) and formula-fed (FF) infants during the first period of life. METHODS: A cross-sectional study was conducted on fasting blood venous samples obtained from exclusively BF (n=106) and FF (n=100) infants to measure total ghrelin (RIA test), leptin (RIA test) and IGF-I (chemiluminescence). Anthropometrical measurements of weight, length and cranial circumference were performed. RESULTS: During the first 4 mo of life, FF infants compared to BF ones showed higher ghrelin levels (2654.86 vs 2132.96 pg/ml; p<0.032), higher IGF-I levels (3.73 vs 3.15 ng/ml; p=0.00) and lower leptin levels (0.68 vs 1.16 ng/ml; p<0.04). Leptin values were higher in females than in males (0.80 vs 0.47 ng/ml; p<0.03), while no gender-related difference was found for ghrelin and IGF-I. No differences were found in anthropometrical measurements comparing the two groups of infants. A multiple regression analysis showed an inverse correlation between ghrelin and leptin values (p<0.04) and between IGF-I and leptin levels (p=0.00). CONCLUSION: Our finding suggests that breastfeeding influences hormones such as ghrelin, leptin and IGF-I in infancy, mainly during the first 4 mo of life. Further evidence is needed to confirm and clarify the role of a protective link from mother to infants as seen in our observations.

A randomized double-blind placebo-controlled trial of a standardized extract of Matricariae recutita, Foeniculum vulgare and Melissa officinalis (ColiMil) in the treatment of breastfed colicky infants.

OBJECTIVE: The aim of this randomized, double-blind, placebo-controlled trial was to investigate the effectiveness and side effects of a phytotherapeutic agent with Matricariae recutita, Foeniculum vulgare and Melissa officinalis in the treatment of infantile colic. METHODS: 93 breastfed colicky infants were enrolled, the diagnosis was made according to Wessel's criteria. After a 3 day observation period, the infants were randomly divided into two groups, one treated with phytotherapeutic agent (PA) and the other with placebo twice a day for 1 week. Crying time and side effects were recorded. RESULTS: 88 infants completed the trial: 41 in the PA group and 47 in the control. The daily average crying time for the PA was 201.2 min/day (SD 18.3) at the baseline and 76.9 min/day (SD 23.5) at the end of the study; for the placebo it was 198.7 min/day (SD 16.9) and 169.9 min/day (SD 23.1) (p < 0.005). Crying time reduction was observed in 85.4% subjects for the PA and in 48.9% subjects for the placebo (p < 0.005). No side effects were reported. CONCLUSION: The present study shows that colic in breastfed infant improves within 1 week of treatment with an extract based on Matricariae recutita, Foeniculum vulgare and Melissa officinalis.

Bioelectrical impedance vector distribution in the first year of life.

OBJECTIVE: We assessed the bioelectrical impedance vector distribution in a sample of healthy infants in the first year of life, which is not available in literature. METHODS: The study was conducted as a cross-sectional study in 153 healthy Caucasian infants (90 male and 63 female) younger than 1 y, born at full term, adequate for gestational age, free from chronic diseases or growth problems, and not feverish. Z scores for weight, length, cranial circumference, and body mass index for the study population were within the range of +/-1.5 standard deviations according to the Euro-Growth Study references. Concurrent anthropometrics (weight, length, and cranial circumference), body mass index, and bioelectrical impedance (resistance and reactance) measurements were made by the same operator. Whole-body (hand to foot) tetrapolar measurements were performed with a single-frequency (50 kHz), phase-sensitive impedance analyzer. The study population was subdivided into three classes of age for statistical analysis: 0 to 3.99 mo, 4 to 7.99 mo, and 8 to 11.99 mo. Using the bivariate normal distribution of resistance and reactance components standardized by the infant's length, the bivariate 95% confidence limits for the mean impedance vector separated by sex and age groups were calculated and plotted. Further, the bivariate 95%, 75%, and 50% tolerance intervals for individual vector measurements in the first year of life were plotted. RESULTS: Resistance and reactance values often fluctuated during the first year of life, particularly as raw measurements (without normalization by subject's length). However, 95% confidence ellipses of mean vectors from the three age groups overlapped each other, as did confidence ellipses by sex for each age class, indicating no significant vector migration during the first year of life. CONCLUSIONS: We obtained an estimate of mean impedance vector in a sample of healthy infants in the first year of life and calculated the bivariate values for an individual vector (95%, 75%, and 50% tolerance ellipses).