6 to 8 hrs for digestion. it stays in the stomach for 2 hours and then in the intestine for another 2 hours. the undigested food goes to the large intestine and the digested food goes to whole body through blood. Carbhydrates and proteins about 1 1/2 -2 hrs. Fats 2 hrs.
And based on that a foetus does not posses self-awareness. Human babies have been found to become self aware between the ages of 18-24 months. The rouge test is a self-recognition test that identifies a human child's ability to recognize a reflection in a mirror as his or her own.
Self-awareness is the capacity for introspection and the ability to recognize oneself as an individual separate from the environment and other individuals. It is not to be confused with consciousness in the sense of qualia.