It needs to be appreciated that Class 4 NICs are only not due by the self-employed with profits in excess of the lower annual profits limit if under 16 or he/she reached state pension age (SPA) before the start of the tax year in question.
The start of the tax year is 7 April for this purpose, so anyone born on 6 April is exempt for the tax year which factually started on that day.
As and when the SPA rises, liability to Class 4 NICs continue. As an example, a woman born on or before 5 April 1951 is not liable to Class 4 NICs as from 2012/13, whereas when her SPA was 60 they ceased to be due from 2011/12.
