Its important to understand for every parent that "Not noticing the delay in time" is real delay.
Often parents sit at home, saying he will learn sooner.. his mom or dad also learnt it late.. or whats the urgency etc
Please donot fall into a trap; by accepting delay in development or growth of a child normal; we are halting the progress of the child.
Visit your doctor, ask when to worry about a delay; when not to worry about a... delay. What is the maximum potential of the child? is he lagging behind peers of same age in certain areas of development? to what extent it is normal? what may happen if u donot note in time?
Its important for us to understand that any delay is rectifiable only if picked up early and intervened early by some brain training therapies; that your occupational therapist or pediatrician may guide about.
Certain delay if not noted in time may cause serious mental retardation. A common known reversible cause of developmental delay is dietary iodine deficiency related hypothyroidism; which gets reversed with near normal intellect once the disease is diagnosed and started on medications.#
There is a huge market stressing you from nutritional advertisements stating that marginal under performance can be related to iron or DHA or calcium or other micronutrient deficiency. Surely malnutrition is an important reason for developmental delay.
When a doctor assesses a child with labelled developmental delay like say delayed smile, delayed sitting, delayed rollover, delayed sitting, delayed standing walking running or comprehending in words or social interactions; the doctor has kept in mind all these causes to decide about action plan. Neverthless, the detailed neurological examination also helps a doctor to decide the need for evaluation of serious neurological disorders from cerebral palsy, autism, etc to neurodegenerative disorders and strokes.
Early Intervention therapy, helps child cope up with the lag and develop a step in milestone development by training the developing cortex using vaious sensory,vibrations/kinaesthetic senses.