Measuring unintended pregnancy (cont.)

Unintended births

Wanted/unwanted fertility rates

Use of desired and living number of children

This approach uses desired and living number of children to classify specific births were wanted or unwanted. A birth is defined as wanted if the number of living children at the time of conception of the birth is less than the ideal number of children as reported by the respondent. Age-specific and total wanted fertility rate can be calculated in the same approach as the total fertility rate except that the births in the numerator exclude those exceeding the ideal number of birth at the time of the survey. Unwanted fertility rates can be obtained subtracting total wanted fertility rate (TWFR or TWR) from TFR, or in the same manner including only unwanted births in the numerator.

Age-specific wanted fertility rate (ASWFR) for age group 15-19 is constructed as below.

A S W F R f o r 15 − 19 = n u m b e r o f w a n t e d b i r h s t o w o m e n a g e d 15 − 19 i n a s t a t e d p e r i o d n u m b e r o f w o m e n a g e d 15 − 19 i n t h e s t a t e d p e r i o d

DHS usually uses births in 1-36 months prior to a survey.

Once you calculate ASWFRs for all the seven 5-year age groups, you can obtain total wanted fertility rate as below.

T o t a l W a n t e d F e r t i l i t y R a t e = ∑ a = 1 7 A S W F R × 5

where

  • a = 1-7 to the seven 5-year age groups

Advantage

This measure does not use the retrospective fertility preference which is vulnerable to post-factum rationalisation.

Limitations

This measure does not account for mistimed births. As mentioned in the earlier section on fertility ideals and norms, a number of women report a non-numeric answer to the question on desired number of children; and ideal total family sizes are likely to be in part influenced by a rationalisation of their existing number of children. Therefore, there is likelihood that an unwanted fertility rate estimated by this measure is underestimated.

Comparison with other methods

This measure produces higher level of unwanted births than the estimates derived from the retrospective direct question on preferences of recent births, but usually lower than the estimates derived from prospective fertility intention.

(Bongaarts 1990, Casterline and El-Zeini 2007, Westoff 2010)

References:

Rutstein S and Rojas G (2006). Guide to DHS Statistics external link. ORC Macro.

Lightbourne RE (1985). Individual preferences and fertility behaviour. In Reproductive Change in Developing countries: Insights from the World Fertility Survey, edited by J. Cleland and J. Hobcraft. Oxford: Oxford University Press. pp165-198.