Week 4

Check out what how your baby is developing this week: -

• The tiny embryo burrows into the wall of the uterus until it's completely embedded and keeps getting bigger every day.
• The ovaries are pumping out the hormone progesterone to make the endometrium tough.
• The sex of your baby, the colour of its hair and eyes, how tall it can grow and whether it has natural footy talent - all these factors have been genetically programmed from the start, and can't be altered.
• By the end of this week the embryo's about a fifth of a millimetre - still too little to see without using magnifying instruments.

Click here for more information and to buy a copy of The Rough Guide to Pregnancy & Birth.