Brain development in relation to fetal weight and maternal glucose tolerance during normal gestation.

Parameters of brain development were studied in near term guinea-pigs in relation to fetal weight and maternal glucose tolerance during normal gestation. Seven litters (22 fetuses) were studied. Fetal weight ranged from 43 to 94 g (119% variability) and the maternal glucose index (sum of the 7 serum glucose levels during the oral glucose tolerance tests) from 921 to 1,528 mg/dl (66% variability). The weights of the cerebrum and cerebellum were less affected by changes of fetal weight compared to other fetal organs. Significant correlations were observed between the maternal glucose index and brain cell number (DNA) and myelination (cerebroside-sulfatide). These variables did not correlate with fetal weight. Liver weight (% fetal weight) and cell number also correlated with the maternal glucose index. It is speculated that the amount of glucose available to the brain could be responsible for the relative protection of the brain to fetal malnutrition and also for the link between maternal glucose index and parameters of fetal brain development.