FERTILITY TREND IN NIGERIA: AN ASSESSMENT USING PERIOD PARITY PROGRESSION RATIOS

Abstract

Nigeria had only successfully reduced total fertility rate by 0.5 children for the period of a quarter of a century using values derived from age-based measurements. Age-based measures of fertility such as the total fertility rate is unreliable in establishing trend because of tempo effect - displacement of births forward or backward, furthermore, given the high prevalence of age errors in Nigerian data, a measure such as the total fertility rate that uses age as the standardizing factor is incompetent in establishing trend. The objective of the present study is to assess fertility trend in Nigeria using period parity progression ratios. Using the 2013 Nigeria Demographic and Health Survey, synthetic parity cohort approach to the computation of period parity progression is used to measure the fertility trend in Nigeria. Conventional age-based measure from the Demographic and Health Survey programme is compared with what derives from the period parity progression ratios. A single calendar year trend in fertility was established from 1992 till 2012 which showed on an overall basis that fertility was constant for ten years from 1992 - 2002 at a level in the region of 6.2 births per woman (there were outstanding years in between, where fertility rose as high as 6.5 births and fell to 5.8 births per woman). The second half of the 20-year period from 2002 - 2012 saw gains in fertility decline up to 5.1 births in 2011. The measures provided in this paper points to the fact that fertility has been declining but very slowly and it also revealed there has been notable decline in the number of women going on to have the more than 5 children, the proportion of women who have remained childless in the population has not changed much over the years. Another vital discovery was that the fraction of women with exactly 4 children has risen steadily from the 1990s going forward.