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Ntoimo

measured fertility preferences with a desire to have an additional child. Although the desire for an additional child is
indicative of fertility preference, it is more of reproductive intention than family size preference (Bongaarts, 1992). The
current research examined the family size preferences of women in a union, indicated by IFS and factors associated with
their preferences. The results of this study contribute to the global discourse on sub-Saharan African fertility by examining
factors influencing women’s IFS. Furthermore, the study highlights changing values about childbearing and fertility
preference transition in Nigeria. Bongaarts (2011) argues that persistent high fertility preference in sub-Saharan Africa is
a strong factor that will keep TFR at a high level for some years to come even when the unmet need for contraceptives in
the region is largely met.
IFS as an indicator of family size preference has two potential sources of bias – ex-post rationalization and non-
response, but because its interpretation is straightforward it is still widely used as a standard indicator of lifetime fertility
goal (Bongaarts and Casterline, 2015). Following Bongaarts and Casterline (2015), to overcome the bias that may arise
from ex-post rationalization, the present study was limited to women whose first marriage took place within 10 years
before the survey. Women whose marriages are of longer duration (more than 10 years) are likely to have completed
childbearing or have had four or more children. To justify their number of living children, the reported IFS of such women
is likely to be influenced by their current family size.

2. Data and Methods
2.1. Setting

This study was conducted in Nigeria. Administratively, Nigeria is made of up 36 States and the Federal Capital Territory,
Abuja. The 37 States are further grouped into six geopolitical zones also called regions – Northcentral, Northeast,
Northwest, Southeast, South-South, and Southwest. The Northern regions are predominantly Islam, whereas the South
is predominantly Christian. The regions are culturally heterogeneous, with over 250 ethnic groups, and many Nigerian
societies are largely patriarchal (Izugbara, 2004; Ntoimo and Isiugo-Abanihe, 2014). Men, and in some cases, the
husband’s extended family had the final say on family size (Isiugo-Abanihe, 1994; Izugbara, 2004). However, there has
been improvement in factors that enhance women’s control of their fertility behaviour. For instance, women’s access to
education and paid employment has continued to increase. The percentage of women who have no education declined
from 42% in 2003 to 35% in 2018, and the proportion who are employed increased to 65% in 2018 from 59% in 2008
(National Population Commission (NPC) [Nigeria] and ICF, 2019).

2.2. Data source

Cross-sectional micro-level data were obtained from the 2018 Nigeria Demographic and Health Survey (NDHS). The
DHS makes use of standardized questionnaires to obtain data on socioeconomic, demographic, and health characteristics
from a nationally representative sample of women and men selected in households. The respondents were selected through
a stratified multi-stage sampling technique. Data collection for the 2018 NDHS took place from August to December 2018
in 40,427 occupied households out of the 42,000 households in the sample. All women aged 15–49 who were either
permanent residents or visitors who slept over the night before the survey in these households were eligible for interview.
Men aged 15–59 in one-third of the 42,000 households were eligible to be included in the study. With a response rate
of 99%, a total of 41,821 out of 42,121 eligible women, and 13,311 out of 13,422 men were successfully interviewed in
the 40,427 occupied households (National Population Commission (NPC) [Nigeria] and ICF, 2019). The present study
draws on data from the women’s individual recode of the household survey. A weighted sample of 13,674 women aged
15–49 years who were in union (married or living together/cohabiting) at the time of the survey and whose first marriage
took place within 10 years before the survey were selected for this study.

2.3. Dependent variable
The dependent variable was IFS, which was indicated by the ideal number of children in the DHS. Respondents who had
living children were asked: “if you could go back to the time you did not have any children and could choose exactly the
number of children to have in your whole life, how many would that be?” Those who had no living children were asked
the number of children that they would have in their whole life-time if they could choose. The responses to these questions
were both numeric and non-numeric. For descriptive and multivariable analyses, this variable was categorized into three:
0 – 3, 4, and 5+. The categorization into three was intended to highlight transitions in the desired number of children
toward a lower fertility preference regime, preferences around Nigeria’s recommended four children per woman (Federal

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