•A KNBS official told the Star unpublished data confirms many families are migrating from western Kenya and settling in Trans Nzoia, where ample, cheaper land is available.
•Women in Tharaka Nithi and Meru have one of the highest use of contraceptives to prevent pregnancy
The decline or stagnation of population in some counties is caused by out-migration, use of contraceptives and deaths, the Kenya National Bureau of Statistics says.
KNBS director general Zachary Mwangi says, for now, this is the most likely explanation for counties whose population declined or didn't grow as leaders had projected.
"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.
He spoke in Nairobi on Thursday during a meeting with editors.
Mwangi asked Kenyans to be patient, saying the bureau did not have all the answers, until all the components of the census data have been anaylsed.
He said rapid urbanisation could also be responsible for population bursts in some places.
Mandera County politicians have already disputed the decrease in population from 1.02 million people in 2009 to 867,457 in 2019.
Kisii leaders also claim the reported increase of people in the Kisii and Nyamira counties was too marginal, yet their tribe has high fertility rate of about four children per woman.
In the 2009 census, Kisii had a population of 1,152,282 people while Nyamira had 598,252. In the 2019 results, Kisii has 1,266,860 people and Nyamira 605,576.
However, a KNBS official told the Star unpublished data confirms many families are migrating from western Kenya and settling in Trans Nzoia, where ample, cheaper land is available.
Mwangi further said the results only captured people where they were found during the census, not their ancestral counties.
"This census was conducted on de facto basis, meaning we counted people where we found them, not where they usually live," he said.
"This was in line with United Nations principles and recommendations for conducting censuses."
He says the sluggish growth can also be explained by the 2014 Kenya Demographic and Health survey, which shows the majority of Kenyan women, having embraced family planning, are now bearing fewer babies.
The number of women (15 — 49 years) using contraception doubled from 39 per cent in 2009 to at least 60 per cent, according to the Ministry of Health.
The lowest births are in Kirinyaga where a woman gives birth to an average two children only, to the highest of eight children per woman in Wajir County.
Twenty-two counties have a contraceptive prevalence rate above the national average, the 2014 KDHS says.
The seven counties with the highest rate include Kirinyaga (81%), Makueni (80%), Meru (78%), Machakos (76%), Tharaka-Nithi and Kiambu (74% each), and Nyeri (73%).
Leaders from Tharaka Nithi and Meru on Tuesday said they will sue KNBS because the census showed their population growth slowing down.
The ten counties with the lowest contraception use include Mandera and Wajir (2% each), Garissa (6%), Turkana (10%), Marsabit (12%), West Pokot(14%), Samburu (23%), Isiolo (27%), Tana River (29%), and Kilifi (34%).
However, these 10 counties have Kenya's highest child mortality rates, and the highest disease burden.