Tempo effects on period fertility in turkey: a study from Turkey demographic and health surveys

Tuğba Adalı, Hacettepe University

One of the disadvantages of the widely used period fertility indicator Total Fertility Rate is that it is subject to tempo distortions caused by changes in the timing of childbearing. Studies regarding these distortions are widely focused on developed countries in literature, however, very few are available for developing ones. Turkey has been experiencing fertility decline since the 1950s. Increasing mean ages at childbearing have accompanied this decline. This suggests that studies regarding tempo effects are necessary for Turkey as well. Bongaarts and Feeney (1998) have proposed an adjustment procedure to correct TFR for tempo distortions using changes in the mean ages at childbearing by birth order, to calculate an adjusted TFR that reflects the level of fertility that would have been observed in the absence of changes in timing. This study aims to try to reveal the tempo in recent period fertility in Turkey by using this adjustment. Since a vital registration system to provide necessary data is not available in Turkey, the adjustment is applied on data from three successive demographic surveys, the Turkish DHSs of 1998 and 2003, using an adoption of the adjustment as used by Lesthaeghe and Willems (1999). Additionally, the study aims to calculate tempo effects for different subgroups of women based on different variables: Type of residence, region, migration status, mother tongue and education to find out whether tempo effects differ with respect to different subgroups and to see which are more likely to be responsible for them. Preliminary findings suggest that there exists increases in mean ages at childbearing and thus significant tempo distortions, proving a tempo approach necessary for Turkey. Although results differ for 1998 TDHS and 2003 TDHS, in general, tempo effects seem to be substantial for Kurdish, rural and less educated women.