Recent fertility change: quantum and tempo effects

Non-Reproductive Life Table (NRLT) and the Reproductive Life Table Parity Distribution (RLT-PD) give the reproductive history of a hypothetical cohort of women assumed to reproduce according to the given schedule of Age-Specific Fertility Rates (ASFR) by single years of age, and is not affected by mortality and/or migration. From these Tables the following measures can be obtained – Total Fertility Rate (TFR), Intensity of Child Bearing (ICB), Ultimate Proportion of Women Not Reproducing (UPWNR), Mean age of fertility schedule (m), Expected Years of Motherhood at starting of Reproductive Life (E(15M)), Average age at First Birth (AFB), Average age at Last Birth (ALB), Percentage distribution of Births by Parity (% by Parity), Reproductive Life Table Parity Progression Ratios (RLT-PPR), average ages at different parities (Mean age at Parities), and Reproductive Life Table Closed Birth Intervals (RLT-CBI). These are standardized measures very useful for comparing fertility situations over time as well as between populations. These Tables are constructed for 14 countries around the World for which ASFR schedules were available from the United Nations Demographic Year Books. It is seen that reproduction has become concentrated in (20-34) age range and lower TFR is always associated with high UPWNR.

Population growth is an issue of concern in most of the developing countries. India is a large (population-wise) developing country with cultural, social, economical and behavioral diversities. In many studies regression or indirect estimation procedure has been used to find out the fertility variation in the population. Uttar Pradesh is the most populous state and it plays a very crucial and important role in population growth of India. In this study a recent pattern of number of births has been analyzed considering the currently married females of Uttar Pradesh who has delivered at least one child in last five years. Parametric regression model is used in order to find out the current scenario of the fertility behavior of the females. Number of birth delivered by a female in last five year has been taken as predicted variable and some socio-economic and demographic variables have been taken as predictor variables to explain the reproductive phenomenon of the females in the traditional society of Uttar Pradesh. Findings clearly show that place of residence, age, number of existing children and their sex composition, wealth index, castes/religion are emerged as a potential factor to explain the phenomenon consider in this study.

Data collected through demographic surveys provide complete as well as truncated birth history, which may be a five, six or seven year period prior to the survey date. When past fertility rates are well documented and one is interested only in the current trend of fertility, which is highly affected by high contraceptive prevalence; data based on truncated birth history may be suitable and economical. However, there is an earnest need for developing suitable analytical tools for analysing such types of data. In the present study, we have used an index in different age segment of female based on a model suggested by Lawless (1987) and also discussed its property. The index explains the shape of the changing pattern of current fertility experience for the data considered in this study. The data for the analysis have been taken from first and third round of National Family Health Survey of Uttar Pradesh. The findings reveal that education, age, religion/caste and place of residence are strong co-variates of fertility regulation.

Previous work on the demographic explanation for recent rises in the fertility rates in Europe concluded that the main driver was declining postponement, leading to higher peak rates (Bongaarts and Sobotka, 2012). Using data from 15 countries in the Human Fertility Database, we found that this explanation was insufficient. We then investigated other possible explanations of the rise. An increase in intensity (i.e. rise in peak rates) was seen in some countries, but not all. Increased variability in age at first birth (which adds to the width of the fertility curve) has been increasing across all the countries studied, although this trend was already underway in the 1990s. Two parallel trends have led to a widening of the fertility curve: a slowing in the decline of first births to young (pre-modal age) mothers and a significant growth in older (post-modal age) entry into motherhood. The turning point from declining first birth fertility rates to increase can be explained by the interplay of ongoing increases in the width of the fertility curve (more variable timing) together with a stabilisation or, in some cases, a modest increase, in the peak rate (intensity). This explanation is valid for both Eastern and Western European countries.

The Sultanate of Oman, a Middle Eastern Arab country, is a pro-natalist country with high fertility, where official population policy is not in place. Nevertheless, the fertility rate has declined dramatically from a very high rate of 8.6 births per women in 1988 to 4.8 births per woman in 2000, a decline of nearly four births per woman with in a short period of twelve years. This paper provides critical review of the fertility transition in Oman and identify the direct and indirect determinants of declining fertility in the 1990s. The study is based on recent national level population base surveys data in Oman. The results indicate that a decrease in the age-specific proportions of women who are married, followed by an increase in contraceptive use are the most important mechanisms by which fertility has declined in Oman. Post-partum infecundability also play important role in fertility control in Oman. Women education and employment are likely factors that encourage couples to delay marriage and use modern family planning methods and thus reduce marital fertility. The decline in fertility in Oman is strongly related to socio-economic development. The findings of the study have important policy implications for national level population planning.

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 rapid economic growth and resulted impact on house hold income in India have been accompanied by major rapid changes in population. Hence, this has also resulted in the overall fertility decline in the country. During the recent decades of development, especially in the post liberalization period the country as a whole has witnessed not only economic growth but also expansion of infrastructural facilities, unexpectedly, this has provided added impetus to population growth through a demographic transition. There have been significant changes in the entire course of population movement in India, especially in the growth and distribution of population and more importantly in its age structure transition. In view of this, the present exercise tried to analyze the major changes in population groups such as children, youth, adults and elderly population with respect to southern states of India. The data for the study have come from Census, Sample Registration System (SRS) and indiastat.com website. For the study a comparative analysis has been done to examine the effects of TFR decline on changing age structure population during the recent decades i.e. from 1991 to 2011 across the southern states of India.

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.

Migrant fertility has become an increasingly prominent explanation for recent fertility change. Immigrant Total Fertility Rates (TFRs) are consistently higher than native TFRs in the majority of European countries. However, research has cast doubt on the use of tempo-distorted measures of fertility for evaluating the contribution of immigrants to aggregate fertility. Furthermore, previous research has almost exclusively analysed incomplete fertility profiles, an approach which provides little insight into the absolute impact of immigrant fertility.

Considering the UK, this research uses survey estimation and count regression techniques to disentangle tempo variation from the quantum of immigrant fertility. This approach is crucial for testing migrant fertility hypotheses because migration is known to influence the timing of childbearing. The results support several hypotheses, with evidence of disruption followed by elevated fertility, particularly for recent cohorts of women arriving after age 25. This may be explained by selection, anticipation, or adaptation. However, the results show no evidence of disruption for immigrants from Jamaica or Bangladesh, suggesting cultural maintenance or socialisation for these groups. The paper concludes with an appraisal of the method used here, and its benefits for future research.

This paper examines the factors associated with interval between marriage and first birth in Iran. Data were generated through in-depth interviews conducted with 30 married women aged 20-49 in Tehran. The result has shown that a short delay of entry into motherhood within the first three years of marriage has been common among women in their 20s who were born in the 1980s and thereafter. According to this study, delayed motherhood allows the women to reducing of costs of early marriage. In fact postponement of first birth is a compensatory strategy for women in Iran. This postponement has strong associations with marriage age, being a student and tendencies of women for higher education. The postponement also results from the fewer financial resources of young couple and their more valuation to family and children quality. However some indirect social control such as infertility stigma, social disapproval along with reducing continued interaction with extended family, restrict longer interval between marriage and first birth.
Keywords— first birth interval, marriage, motherhood, survival analysis, qualitative survey, Iran