This is because they are in fact younger and your baby should be assessed according to their corrected age. This is the age they are from their term due date.
Your baby’s development will be regularly assessed and monitored by their healthcare professional. This should reassure you that your baby is doing well and also address any concerns you may have.
Some babies may need extra support from a physiotherapist or occupational therapist to help develop their strength and muscle tone.
Your baby may be given some gentle exercises or activities for you to help them achieve this. If you have any concerns about your baby’s development, then you should discuss this with your healthcare professional.