Conception: The Father’s sperm fertilises the Mother’s egg cell. From the moment of conception, 46 chromosomes with 30,000 genes combined to determine all of your physical characteristics: sex; facial features; body type and the colour of your hair, eyes and skin. Even more amazing, intelligence and personality - the way you think and feel, your talents, tastes, athletic abilities and more - were already in place within your genetic code. At the moment of conception, you were already essentially and uniquely 'you' - no bigger than a grain of sugar.
30 hours after conception
First Day: Between 12 and 30 hours after fertilisation, cell division begins. At this stage, the cells are no larger than the head of a pin. Cells continue to divide every 12 to 15 hours - two into four, four into eight and so on. By the time you reach adulthood, there will have been 45 doublings of cells, producing about 30 million millions of cells.
8 days: Now a ball of several hundred cells, the fertilised egg burrows into the wall of the mother’s womb.
24 days: In just over three weeks you are already one-sixth of an inch long and rapidly developing. Your backbone, spinal column, and nervous system are forming, and the kidneys, liver, and intestines are taking shape. The heart is beating regularly now and is pumping your own blood, separate from your Mother’s.
1 month (4 weeks): From one cell to millions of cells, you have grown 10,000 times over and are now 6-7 mm long. Already your eyes are developing, the buds of your arms and legs are appearing and forty pairs of muscles are forming along your spine. Your heart is no larger than a poppy seed at this stage.
5 weeks: The pituitary gland is forming in the middle of the brain and the neural tube enlarges into three parts, soon to become a very complex brain. Your mouth and ears are taking shape and the spine and spinal cord grow faster than the rest of the body at this stage and give the appearance of a tail. This disappears as you continue to grow. Already your sex can be determined.
6 weeks: Your embryonic heart is fluttering at 140-150 beats per minute - twice as many as your mother’s. Your skeleton is already forming (in cartilage, not yet bone), and your brain coordinates how your muscles and organs move, and you have already begun to develop reflexes like responding to touch
7 weeks: Your facial features are now visible, including the eyes, ears, nose, lips and tongue. The eyes have a retina and lens, and buds of milk teeth have appeared. The major muscle system is developed, and you are beginning to move spontaneously. You now have your own blood type, distinct from your mother’s. More than 100,000 new nerve cells are created every minute. Brain waves can now be recorded by an EEG.
2 months (8 weeks): You now measure about three centimetres long and weigh in at just one gram. You are already well-proportioned with tiny fingers and toes, well-established hearing and balance mechanisms, individual fingerprints and a sturdy heart beat. Everything to be found in a fully grown human being has already been formed. You swim and move gracefully in your mother’s womb, swallowing and "breathing" amniotic fluid, which is good practice for your digestive system.
9 weeks: Already you can bend your fingers around an object placed in your palm. Your fingernails are forming and you may even start to suck your thumb. Already the brain and nerve fibres necessary for pain sensation are functioning, and you would try your hardest to avoid the source of any pain.
10 weeks: Your heart is almost completely developed and closely resembles that of a newborn baby. The heart’s energy output is also well over 30 per cent of an adult’s. Already you are squinting, and puckering up your brow and frowning - next week you will be able to smile!
3 months (12 weeks): Now 9 cm long and weighing 45 grams, your brain, lungs and vocal chords are formed, and you sometimes hiccup and even cry (silently). Already your behaviour shows distinct individuality and you can kick your legs, curl and fan your toes, make a fist, move a thumb, bend your wrist, turn your head, open your mouth and press your lips together.