The basics of making babies seem simple. You need sperm, an egg, and a womb to incubate in. Combine those, and a baby starts to grow. However, most people don't know what develops first in the womb as far as the baby's growth. Does it start with a brain? A heart? What organs come first during pregnancy, and what organs develop last?
The order of organ development in fetuses isn't always exactly the same. Humans all start from the same general blueprint, but some organs start to form around the same time, and some grow faster than others. But here's what science says: babies start as an anus (really), and end by developing lungs. When - and how - body parts grow in between is a long and fascinating process.
Brain, Spine, And Placenta