Age at peak height velocity in Polish adolescents: Effect of socioeconomic factors.

Age at peak height velocity (APHV) is an indicator of maturity timing which is applicable to both sexes, and which is influenced by environmental factors. The objective of this study was to assess variation in APHV associated with several indicators of socioeconomic status (SES) in a longitudinal sample of Polish adolescents. The sample included 739 boys born in 1983 and followed annually from 12 to 16 years, and 597 girls born in 1985 and followed annually from 9 to 13 years. The height records were fitted with the SITAR model to estimate APHV. SES was estimated using principal component analysis of indicators of familial status based on parental education, family size, living conditions and household possessions. Statistical analyses included analysis of variance (one-way for general SES and three-way for parental education and family size) and Tukey post-hoc tests for unequal samples. General SES (p <.001) and family size (p < .05) significantly influenced APHV among boys, while only maternal education (p < .05) significantly influenced APHV among girls. Among youth from families of higher SES, as defined by the respective indicators, APHV was attained significantly earlier, on average, than in peers from families of lower SES. Overall, the results showed a sex-dependent effect of SES on APHV, and highlighted the influence of favorable socioeconomic conditions for optimal growth and maturation during adolescence.

Social mobility of the father influences child growth: A three-generation study.

OBJECTIVES: The association between body height and social status is known. We were interested in the effect of intergeneration changes in social status on height. METHODS: Body height was measured in 2008 paternal grandfather-father-son and 1803 paternal grandfather-father-daughter triplets. The sample consisted of four child cohorts born in 1988, 1985, 1983, and 1980, and was measured annually from 6 to 11, 9 to 14, 11 to 16, and 14 to 18 years of age. Triplets were dichotomized according to grandfathers' occupation, into one "lower" and one "upper" grandparental class; and according to paternal education, into one "lower" and "upper" paternal class, resulting in four "family histories": two nonmobile (grandfathers and fathers stayed in the same social class), and two mobile histories (social class of fathers and grandfathers differed). RESULTS: "Upper" class fathers are taller than "lower" class fathers. This class effect on height persists into the third generation. Upward social mobility ("lower" class fathers receive secondary or university education) results in taller stature both in the fathers and in the children. The opposite applies for downward social mobility. "Upper" class fathers with only basic or vocational education lose the social advantage and remain shorter. So do their children. CONCLUSIONS: The class effect on height tends to persist into the next generation, but depends on education. Upward social mobility measured as a "better" education, results in taller stature, up to the third generation. The study highlights the importance of education as a major regulator of body height.

Isolation by distance between spouses and its effect on children's growth in height.

Heterosis is thought to be an important contributor to human growth and development. Marital distance (distance between parental birthplaces) is commonly considered as a factor favoring the occurrence of heterosis and can be used as a proximate measure of its level. The aim of this study is to assess the net effect of expected heterosis resulting from marital migration on the height of offspring, controlling for midparental height and socioeconomic status (SES). Height measurements on 2,675 boys and 2,603 girls ages 6 to 18 years from Ostrowiec Swietokrzyski, Poland were analyzed along with sociodemographic data from their parents. Midparental height was calculated as the average of the reported heights of the parents. Analyses revealed that marital distance, midparental height, and SES had a significant effect on height in boys and girls. The net effect of marital distance was much more marked in boys than girls, whereas other factors showed comparable effects. Marital distance appears to be an independent and important factor influencing the height of offspring. According to the "isolation by distance" hypothesis, greater distance between parental birthplaces may increase heterozygosity, potentially promoting heterosis. We propose that these conditions may result in reduced metabolic costs of growth among the heterozygous individuals.

The level of physical fitness in children aged 6-7years with low birthweight.

BACKGROUND: Level of physical fitness is related to the functional status of most of the bodily functions and so it appears to be very important to identify perinatal factors influencing physical fitness. AIM: The purpose of this study was to determine the influence of birth weight on the level of physical fitness in children 6-7years of age. SUBJECTS AND METHOD: Physical fitness was assessed using EUROFIT tests in 28,623 children, aged 6-7years, from rural areas in Poland. Children below the 10th percentile for birth weight for gestational age were defined as small for gestational age (SGA). The influence of birth weight on parameters of fitness was assessed by means of covariance analysis. RESULTS: With the controls of age, sex and body size, children of low birth weight have shown significantly lower levels of body flexibility and running speed. The leg strength of children with SGA turned out to be significantly lower only in 7-year-old boys. CONCLUSION: This study has revealed the significant influence of birth weight on physical fitness. The results suggest the importance of early intervention and its possible benefits for developing and maintaining the proper level of physical fitness further in life.