Wanted total fertility rate
The number of children who would be born per woman (or per 1,000 women) if she/they were to pass through the reproductive years bearing children according to a current schedule of age-specific fertility rates if only “desired” or “wanted” births occurred
For this indicator, “wanted” births are defined taking into account both desired family size and the number of surviving children. All births during a specified reference period (usually the two to five years prior to a survey) that do not exceed the respondent’s stated “desired number of surviving children” are classified as wanted. Births raising the number of surviving children above the desired family size are considered unwanted.
The indicator is calculated as follows:
WTFR = 5∑a (WBa/Ea)
WBa = the number of births to women in age group a in a given year or reference period that are “wanted;” and
Ea = the number of person-years of exposure in age group a during the reference period.
Responses to survey questions on:
- Numbers and dates of births during a recent period (typically the two to five years prior to a survey);
- Desired number of children or family size; and
- Number of children ever born and number surviving.
The WTFR is a measure of “wanted” fertility, a hypothetical measure of what the total fertility rate (TFR) would be given age-specific fertility rates for a recent past period under the condition that all women’s fertility preferences were perfectly realized; that is, if only “wanted” births occurred. The measure represents an attempt to avoid the suspected bias in the wanted status of recent births indicator by defining wanted or desired status on the basis of the consistency (or lack thereof) between the reported desired family size and the number of surviving children, instead of on the basis of retrospective reports of fertility intentions at the time of becoming pregnant.
Evaluators calculate the indicator as the sum of age specific fertility rates, or the total fertility rate, after
they delete births occurring during a specified reference period that raise the number of surviving children of sample respondents above their stated desired number of children.
In the DHS, numbers of births during the specified reference period are derived from the birth history portion of the survey interview, the numbers of surviving children are derived from questions on lifetime fertility and survival status, and the information on desired family size are derived from survey questions.
The comparison of the WTFR with the TFR indicates the extent to which observed fertility exceeds desired or wanted fertility. This type of comparison provides program managers and policy-makers with some insight into the potential short- to medium-term demand for family planning services and the potential for fertility decline in the future (Westoff, 1991). In the case of Burkina Faso, for example, the comparison of the TFR (5.9) with the WTFR (5.1) suggests that a considerable share of current fertility is unwanted and that sufficient latent demand exists in this population; thus an increase in contraceptive prevalence and a decline in fertility might be reasonably expected, if family planning services are available to the population (Institut National de la Statistique et de la Demographie and Macro, 2007).
The above definition of the WTFR is based upon the work of Lightbourne (1985, 1987) and Westoff (1991) (who labels the measure the “desired total fertility rate” or DTFR). Bongaarts (1990) proposed a modified definition of the WTFR in which wanted births are defined on the basis of whether survey respondents desired additional births at the time of a survey instead of on the basis of the comparison of the desired number of children and the number of surviving children. Under this definition, births within a specified reference period are classified as wanted if the respondent reported wanting additional children at the time of a survey.
The argument for the alternative definition is that it is based upon responses to questions on preferences for additional children, an indicator of demand thought to be less affected by reporting biases than the desired family size indicators (Bongaarts, 1990). Comparison of estimates of the two versions of the WTFR for 48 DHS countries indicates that the two measures are reasonably close for most countries, with an average difference between the measures of about 9 percent– 4.09 versus 3.76 (Bongaarts, 1990). On the basis of available evidence, either version of the WTFR is preferable
to using the wanted status of previous births in defining wanted fertility.