Maccoby E E, Doering C H, Jacklin C N, Kraemer H
Child Dev. 1979 Sep;50(3):632-42.
In 3 groups of human newborns, 5 sex hormones were assayed from samples of umbilical-cord blood, and concentrations were analyzed by the sex and birth order of the infants. The 5 hormones assayed were testosterone, androstenedione, estrone, estradiol, and progesterone. Concentrations of testosterone were significantly greater in males than females. The other 4 hormones did not differ significantly by sex. In both sexes, firstborns had significantly more progesterone and estrogens, with progesterone showing the largest birth-order effects. Among male infants, firstborns had higher concentrations of testosterone. The higher concentrations of progesterone in firstborns of both sexes, and of testosterone in firstborn boys, were found not to be due to length of labor, birth weight, or maternal age. However, they were a function of temporal spacing of childbirths. Later borns who were closely spaced in relation to their next-older siblings had lower concentrations of hormones. The effect of temporal separation was greater on male than female infants for each of the 5 hormones studied. The results are discussed in terms of the possible effects of hormone "depletion" on the psychological development of closely spaced later borns.
在三组人类新生儿中，对脐带血样本中的5种性激素进行了检测，并根据婴儿的性别和出生顺序分析了其浓度。所检测的5种激素为睾酮、雄烯二酮、雌酮、雌二醇和孕酮。男性的睾酮浓度显著高于女性。其他4种激素在性别上没有显著差异。在两性中，头胎婴儿的孕酮和雌激素含量显著更高，其中孕酮的出生顺序效应最为明显。在男婴中，头胎婴儿的睾酮浓度更高。研究发现，两性头胎婴儿孕酮浓度较高以及头胎男婴睾酮浓度较高，并非由于产程长短、出生体重或母亲年龄所致。然而，它们是分娩时间间隔的函数。与年龄稍大的兄弟姐妹间隔时间较短的晚出生婴儿，其激素浓度较低。在所研究的5种激素中，分娩时间间隔对男婴的影响比对女婴的影响更大。本文根据激素“消耗”对间隔时间较短的晚出生婴儿心理发育可能产生的影响对研究结果进行了讨论。
