4 week old (5 August - 12 August 2009)

Most babies can now track a moving object with their eyes for longer than a couple of seconds. Try passing a colourful rattle in front of your baby's face. You may be rewarded with coos and gurgles of pleasure. Her head is steadier now, too, and she may even be able to lift it up when lying flat on her stomach on the floor or a changing mat. Short periods of time on the floor will help her strengthen her neck muscle but stay close by, she can easily get tired.

Find out more fascinating facts about your four-week-old's development

3 week old (28 July - 4 August 2009)

Many babies love listening to the sound of human voices, especially high-pitched ones. You're probably using singsong baby talk to communicate with her without even thinking about it. Watch how she turns her head in your direction when you coo over her. Soft music and the sounds of a musical toy will also keep her engaged, but steer clear of very loud environments. Too much noise will either cause her to tune out sounds altogether or start wailing.

Find out more fascinating facts about your three-week-old's development