Many factors have been set forth from time to time as influencing the intra-uterine development of the fetus. Such influences as the age,1 social status,2 number of previous pregnancies,3 length of pregnancy4 and duration of the menses of the mother5 have been mentioned in explanatory hypotheses. Abels6 examined the seasonal variation and found a slight decrease in the average weight of infants at birth during the winter. He explained this on the basis of control by vitamins. It has been shown experimentally that depletion of the vitamin content of the mother's blood is responsible for damage to the fetus and abortion,7 while an increase in the amount of certain vitamins, notably vitamin D, in the diet of the mother influences fetal development favorably.8
The placental factor in the determination of birth weight was studied by Hilgenberg,9 who found that the weight
WOODS EB. SUGAR CONTENT OF MOTHER'S BLOOD AFTER FASTING: ITS RELATION TO THE BIRTH WEIGHT OF INFANTS. Am J Dis Child. 1936;51(2):297–301. doi:10.1001/archpedi.1936.01970140061006
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