The use of contraceptives in some counties in one of the reasons why population did not grow in some counties, Kenya National Bureau of Statistics (KNBS) says.
KNBS director-general Zachary Mwangi on Thursday listed migration of people from their home counties and death as other reasons why some counties recorded less population growth.
He, however, said a clear explanation will be given to the public once a final analysis of the data is done.
"These are the main factors that influence the growth or decline of a population. For now, we are still analysing the data and we will have clear explanation for these thematic areas when we release more reports in the first quarter of next year," he said.
Mwangi held that the 2014 Kenya Demographic and Health Survey (KDHS ) results could also explain why some counties recorded less growth.
KDHS 2014 results indicate that the number of women on contraceptives had increased from 39% in 2009 to at least 60% in 2014.
Kirinyaga recorded the highest number of women on contraceptives at 81% followed by Makueni (80%), Meru (78%) and Machakos (76%).
Others are Tharaka Nithi (74%), Kiambu (74%) and Nyeri (73%).