On the quantum and tempo of fertility

Abstract

Demographers have known since the 1940s that standard measures of period fertility, such as the widely used total fertility rate, are distorted by changes in the timing of childbearing. Period fertility rates are depressed during years in which women delay childbearing and inflated in years when childbearing is accelerated. This problem is usually ignored because there has been no generally accepted method for solving it. This study proposes a method for removing the tempo distortions from the total fertility rate. The key assumption of the method is that period effects, rather than cohort effects, are the primary force in fertility change, an assumption supported by past research. An application of the adjustment procedure to fertility trends in United States shows that concern over below-replacement fertility in the past 25 years has been largely misplaced. Without the distortion induced by the rising age at childbearing, the underlying level of fertility was essentially constant at close to two children per woman throughout this period. Below-replacement fertility in Taiwan since the mid-1980s is also largely attributable to tempo effects.

Realization, Postponement or Abandonment of Childbearing Intentions in Four European Countries

“…During the study period (2001)(2002)(2003)(2004) the mean age of mothers at fi rst birth increased from 25.3 to 26.3 years. Naturally, if the postponement distortion was acknowledged in the calculation of the TFR, then the adjusted fertility would be much higher than actual fertility (Bongaarts and Feeney, 1998).…”

A Cognitive–Social Model of Fertility Intentions

“…The macro constraints (S and P) are the ones that exist in a particular period – and would thus operate on the synthetic cohort. One parameter, and an important one, is removed as we move from a period to cohort representation: this is temporal distortion (see Bongaarts and Feeney 1998). …”

“… 16 Period rates are affected directly and immediately by such postponement (see Bongaarts and Fenney 1998). …”

“…A substantial part of this difference can be explained by fertility postponement (Bongaarts and Feeney 1998). …”

Environmental quality and fertility: the effects of plant density, species richness, and plant diversity on fertility limitation

“…Analyses of the same data used in this paper (described below) reveal that almost all women who had used a long-term contraceptive method said they wanted no more children and over 80 percent of women who first used a contraceptive method between 1996 and 2007 eventually used a longer-term method designed for terminating childbearing (Axinn and Yabiku 2001; Brauner-Otto 2013). Therefore, in this setting, the commonly used phrase in demography “later means fewer” holds true—contraceptive use corresponds with smaller families (Axinn and Yabiku 2001; Bongaarts and Feeney 1998). …”