Sex Differences in the Relationships Among Weight Gain, Subcutaneous Skinfold Tissue and Saltatory Length Growth Spurts in Infancy

Abstract

As the mechanisms controlling the amount and timing of growth saltations are not well understood, the identification of physiologic coupling in weight and length growth are important for further understanding normal growth biology. Thirty-four healthy infants (13 males, 21 females) participated in a longitudinal growth study during the first year. Weekly weights and s.c. skinfolds (limb and trunk) were analyzed in a growth eventfocused study. Coincident analysis tested the null hypothesis of chance concurrence between significant weight gain and saltatory length growth spurts. Logistic regression quantified this relationship and investigated the interaction between incremental weight gain and s.c. skinfolds on length growth spurts. The null hypothesis of random coincidence between weight gain and saltatory length growth was not supported. For girls, significant weight gain and length growth were coupled during the same week and length saltations were 42% more likely during the weeks of significant weight gain, with no interaction from s.c. skinfolds. For boys, length growth saltations were coupled to both previous and concomitant weight gain but were predicted only by previous weight gain, controlling for confounders. Boys were 68% more likely to grow in length the week following significant weight gain, and initial abdominal to suprailiac skinfold ratios conferred a 4-fold increased likelihood of length growth within the week, controlling for confounders. These data generate the hypothesis that a common growth signal cascade couples growth in weight and length/height with a time delay due to sex-specific biology, reflected in a s.c. fat fold interface. While weight and height growth have often been considered to be physiologically coupled (1), how weight gain is related to linear growth during normal infant development is not well understood. As the proximal mechanisms controlling discrete growth spurts are unknown, identifying metabolic influences from weight changes may be important evidence for better understanding the normal biology of growth.Variability in the sequence of weight and height growth patterns have been reported among nutritionally challenged samples. For example, studies of catch-up growth in previously malnourished children have observed that, with the onset of supplementation, repletion of weight and/or weight for height preceded linear growth (2-4). Seasonality studies have, likewise, identified alternating weight and height gains among infants and young children (5). These observations have been reiterated in an animal model that identified immediate weight gain in short-term fasted male rats after repletion, which preceded linear growth rate accelerations in the tibia (6).A logical proposition from these studies is that weight gain is a signal for linear growth. This is in line with a historical "filling and stretching" notion of the relationship between weight gain and longitudinal growth (7). An offset in the timing of weight gain and linear growth may permit adipose tissue accrual to p...

Use of Lipid-Based Nutrient Supplements by HIV-Infected Malawian Women during Lactation Has No Effect on Infant Growth from 0 to 24 Weeks

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Infant Growth in Length Follows Prolonged Sleep and Increased Naps

“…We have previously reported increases in weight and abdominal skinfold changes concordant with length saltations in this sample. 24 The present data suggest that sleep is integrating multiple anabolic processes in normal growth and development. This raises questions regarding anabolic pathways that may be driven during sleep more generally.…”

“…33 ness to participate in the protocol, and was unintentionally weighted to educators and medical personnel. Growth in total body length was assessed using the maximum stretch technique, 23 and weight and subcutaneous skinfolds were measured 24 for durations ranging from 4 to 17 months. Ninety percent of the subjects' measurements were taken at the same time of day (± 1 h).…”

“…Increasing HPB was related to both greater weekly infant weight gain and greater weekly accrual of abdominal skinfolds ( Table 3). As these variables are known to interact with length growth, 24 stratified analyses based on intervals during which a length growth saltation occurred vs intervals when no length growth occurred further explored these relationships. Only at times of growth in length were weight gain and abdominal adiposity accrual associated with increased sleep (P < 0.001, P = 0.05, respectively).…”

Historical Approaches to Human Growth Studies Limit the Present Understanding of Growth Biology

“…As the skeleton is intricately involved in whole-body energy homeostasis [72], scientific understanding of growth biology will be advanced by an integrated approach clarifying relationships between body parameters. Knowing when discrete skeletal growth events actually occur permits the documentation of temporal relationships between weight gain and bone elongation [73], or bone elongation and sleep [74], for example. These relationships generate hypotheses regarding more specific mechanisms regarding metabolic characteristics of individual level growth biology.…”