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By four months of age, both you and your baby will probably have adjusted to a reasonably regular routine. This routine will provide a predictability that will help your baby feel secure. During this period he will learn to coordinate his touch, vision, hearing and other senses with various motor activities to make them more purposeful. For example, he is now capable of reaching out to grasp a rattle, exploring with his hands, or shaking it and listening to the sound.1

This is also the period during which he will be able to better express his feelings, likes and dislikes, and start voicing out them more and more frequently. He becomes very sociable, smiles and plays with anyone he meets.1

The fourth scheduled visit of primary vaccinations is at four months of age. The gap between the doses of vaccines is to make sure that each dose has time to work effectively. This is still injection in the series of vaccinations that are given at two, four, and six months.  Your baby will again receive two injections for prevention against diphtheria, tetanus, acellular pertussis, poliomyelitis and pneumococcal infection.2


  1. Family Health Service. Child Health. Child Development 4 – Four to Seven Months. Available at [Access Apr 2021]
  2. Family Health Service. Child Health. Schedule of Hong Kong Childhood Immunisation Programme. Available  at [Access Apr 2021]