|Image via BabyCenter|
36 weeks after fertilization (38 weeks LMP), Baby Chris is 19 ½ inches long and weighs 6 ¾ pounds—about the size of a leek. The brain has developed "deep, convoluted grooves — extra surface area for neurons." The Endowment for Human Development notes that brain weight doubles during the last nine weeks of pregnancy:
Much of the brain’s weight gain is due to the thickening of the myelin sheath around the nerves. By the end of pregnancy, the fetal brain is about a quarter of its eventual size and contains nearly all the neurons it will ever have: perhaps 100 billion. Each of these neurons will eventually synapse with as many as 200,000 other neurons, creating an electrical network of almost incalculable complexity.For more prenatal development info, download the free See Baby app on your device.