Recent fertility change: quantum and tempo effects. Further perspectives

The postponement or advancement of births increases or decreases mean age at childbearing which in turn, distorts period TFR. This is true for any population undergoing fertility transition. However, despite the ubiquity of strong evidences of postponement of births across countries, research so far on tempo effects is disproportionately focused on developed nations with almost neglected focus in the developing countries. In attempt to fulfill this research gap, this study examines role of the tempo effects in period fertility trends in India. Using merged birth histories of three rounds of NFHS (19992-93, 1998-99, 2005-06), in this paper, we estimated fertility trends and the mean ages at child bearing by birth orders for the past 25 years (1981-2006) in India. Results indicate that cumulated fertility before age 40 in India declined from around 4.5 to 2.7 during 1981-2006 with urban fertility levels being lower than rural areas. Fertility trends by birth order show that fertility declined for all births orders with relatively higher decline for higher order births. The mean age at first birth increased by almost 0.82 years with urban areas showing an increase of 1.1 years during 1981-2006. Results reveal considerable tempo distortions in the period TFRs in India which are more pronounced since 1990s.

Recent studies suggest a rapid change in fertility preferences among young adults across sub-Saharan Africa. In this study, we examine the sensitivity of Malawians’ fertility preferences to a variety of hypothetical (but common) events that may alter fertility preferences and intentions. Using new data from the Tsogolo la Thanzi (TLT) study in southern Malawi, we analyze expected changes in desired number of children (quantum) and the pace of childbearing (tempo) in response to this variety of events. We further employ the Coombs scale, a measure of underlying family size preferences, to predict the direction of both dimensions of fertility preferences. To measure tempo change, the survey questions respondents about their preferred timing to next birth. We find 1) that both the quantum and tempo dimensions of fertility preferences are most responsive to AIDS-related conditions and 2) that young adults’ preferences are relatively impervious to changing economic conditions and family issues. Our results indicate that the generalized AIDS epidemic in Malawi is critically important for understanding young people’s fertility preferences and, ultimately, their behaviors.

This study investigates the genetic component in age at first birth (AFB) for twins from United Kingdom. We decompose the observed variance in AFB into that caused by: genes, shared environment, and the unique environment of twins. We first fit continuous structural equation models followed by the innovation to estimate tobit survival models to include censored cases. Our data contain 2 274 monozygotic (42 %) and dizygotic (58 %) female twin pairs born 1919-1968. Results show that up to 40 % of the observed variance in AFB is due to additive genetic differences. In line with previous research, results underscore the relevance of genetic factors in determining fertility outcomes. A historical comparison of cohorts shows that the genetic component in AFB decreases in more recent cohorts. Results emphasize the relevance of environmental conditions for the expression of genetic predisposition (gene-environment interaction).

The annual figures on the fertility of Turkish and Moroccan women show that the sharp decline that took place up to the mid nineties was reduced or stagnated. In this paper we use cohort data by generation for the main population groups of non-western origin to show that the first generation only adjusted their fertility slowly to that of the native Dutch women. These women of the first generation show comparable (Turkish women) or even higher (Moroccan women) fertility rates than the women in their countries of origin and few signs of assimilation in (fertility) behaviour.
The second generation, on the other hand, are much closer to native women in this respect than to their mothers. Turkish and Moroccan women in their early thirties have almost the same number of children than native Dutch women that age. Adjustment to the native Dutch fertility pattern is caused by intergenerational differences, rather than by cultural assimilation of the first generation.