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Skeletal growth and development of the human fetus : effect of maternal and nutritional factors.

University of British Columbia

Growth is associated with the availability of essential nutrients and it seems possible that these nutrients could affect the growth mechanism involved in skeletal development. To test this hypothesis 76 normal human fetuses aged 9 to 20 weeks were collected from therapeutic abortions. Sex, weight, length, head circumference, foot length and a skeletal index were recorded; developmental age was calculated from crown-rump length, and gestational age estimated from the mother's menstrual history. Bones from the right arm and leg were removed and cleaned for biochemical analysis. Calcium, inorganic phosphorus, magnesium, sodium and collagen content of 60 femora and humeri were determined, after length, fresh weight, constant dry weight and fat-free weight were recorded. Length of ossification in the bones of the left arm and leg was measured via silver radiography. Assuming bilateral symmetry, biochemical and physical data could then be compared. All fetal data were grouped according to developmental age: 9-10, 11-12, 13-14, 15-16, 17-20 weeks. Analysis of variance and Duncan's New Multiple Range Test were performed to determine the significance of group effect. Simple linear regression was executed on the whole range of data to detect which variables best predicted other variables. Maternal information was obtained from an interview and from medical records at Vancouver General Hospital. Age, weight, height, birth weight, parity and gravidity of the mother were recorded. A socio-economic index was calculated. Adequacy of maternal diet during pregnancy was assessed from a daily pattern recall, food frequency and preference questions. These data were used to calculate a total nutrition score and a protein score. Maternal data were coded as potential independent variables and multiple regression analysis performed against fetal dependent variables. As developmental age of the fetuses increased, the fresh length, dry weight and length of ossification also increased in both humerus and femur, as did the calcium and phosphorus content. In most cases long bone growth as measured by these variables advanced proportionately with fetal age. Thus group means of most variables were significantly different from each other when divided into five 2 week age periods. Water content dropped proportionately with age, reflecting bone mineralization. Sodium content fell markedly in fetal bones after 10 weeks. Magnesium and collagen remained constant. Fat extraction did not change the dry weight of the bones. Statistical correlation was found between physical and biochemical data. Generally physical variables were best predicted by other physical variables. Biochemical composition of the femur could best be predicted from corresponding data in the humerus. When gestational age was plotted against physical or biochemical variables, statistical correlation was weaker. The correlation found between fetal variables and maternal age, parity, weight and socio-economic status would indicate a diversity of factors influencing fetal growth. Whereas protein score of maternal diet was not statistically related with fetal parameters, general nutrition score showed a consistent, positive correlation with length and dry weight of the femur and humerus. This relationship was statistically significant when developmental or gestational age remained constant. The results of this study suggest that nutrition of the pregnant woman is positively correlated with some indices of skeletal growth and development of the human fetus.

Text

2011-05-02

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http://hdl.handle.net/2429/34192

Human Nutrition

University of British Columbia

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