Zamenhof S, van Marthens E
Biol Neonate. 1982;41(1-2):68-73. doi: 10.1159/000241519.
During prenatal development, the distribution of nutrients between brain and body is influenced by many factors. Fetal and neonatal ratios may serve as indices of the final outcome; brain weight/body weight (Rw), brain DNA/body DNA (RDNA) and brain protein/body protein (Rprot; similar to Rw). These ratios decrease with fetal age but this dependence on age disappears towards term. Within one age, these ratios show considerable variability (up to 14%), from litter to litter, and within litters. The variability is not due to variation in water contents ( less than 1%). An extensive study of 2,089 normal newborns revealed that 7.5% had Rw values significantly higher than the mean for the population. Of these, 35% had normal body weights but significantly higher brain weights. Thus, they do not represent previously studied cases of general (brain and body) overdevelopment; rather, they represent cases of favorable brain versus body growth, i.e. distribution of nutrients between brain and body that is more favorable for the brain. Such a favorable distribution may be caused by maternal factors if it affects entire litters (3% of all affected) or by fetal factors, if it affects only individuals within a litter (49%).
在产前发育过程中，大脑与身体之间营养物质的分配受多种因素影响。胎儿和新生儿的比例可作为最终结果的指标；脑重/体重（Rw）、脑DNA/身体DNA（RDNA）和脑蛋白/身体蛋白（Rprot；类似于Rw）。这些比例随胎龄增加而降低，但在足月时这种对年龄的依赖性消失。在同一胎龄内，这些比例在不同窝仔之间以及同一窝仔内部都表现出相当大的变异性（高达14%）。这种变异性并非由水分含量的变化所致（小于1%）。一项对2089名正常新生儿的广泛研究表明，7.5%的新生儿Rw值显著高于总体平均值。其中，35%的新生儿体重正常但脑重显著更高。因此，他们并不代表先前研究的普遍（大脑和身体）过度发育的情况；相反，他们代表的是大脑与身体生长良好的情况，即大脑与身体之间营养物质的分配对大脑更为有利。如果这种有利的分配影响整个窝仔（占所有受影响的3%），可能是由母体因素引起的；如果仅影响一窝中的个体（49%），则可能是由胎儿因素引起的。
