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.
When younger infants see their reflections, they point to the mirror and not to themselves. After the age of eighteen months or so, they touch the rouge on their own faces instead of just pointing to the mirror (p. 165). There are other ways in which children give evidence of increased self-awareness.