Foetus during pregnancy. Illustration of a sectioned female abdomen seen from the side, showing a human foetus developing in the uterus during pregnancy. The foetus develops within its mother's uterus, surrounded by a fluid-filled amniotic sac. The placenta (red, pink and white) on the uterus wall acts through the umbilical cord, bringing oxygen and nutrition to the developing foetus, and taking away waste products. Development to full term and birth takes around 37 to 40 weeks. This foetus is near full term. The front of the body is at right, with the lower spine visible at left, and the bladder, birth canal (vagina), and rectum all at lower left.