Environmental factors include maternal and paternal genetics, maternal size, and the capacity of the placenta to provide nutrients to the fetus Alan D. Bocking. Uteroplacental and umbilical blood flow and transplacental glucose and fetal insulin are major determinants of After completing this article, readers should be able to: The principal determinants of fetal growth are fetal genotype and in utero environment. Fetal growth is exponential and during the lastweeks of gestation the fetus gains%