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Birth spacing is of considerable importance to study the tempo and quantum of fertility. Using data from the National Family Health Survey III, this study explored the birth interval dynamics in Odisha, an eastern state of India. The life table analysis of spacing between births clearly suggests that birth spacing in the recent past has increased and the proportion of women moving to the second, third, and fourth parity has declined, leading to the decline in fertility in Odisha. From the proportional hazards model, educational level of women, age of women at previous birth, sex and survival status of the previous child, and the period effect are found to be important determinants of birth spacing at higher parities. Socioeconomic differences do not show a large effect at lower order births. This highlights the fact that most women in Odisha, regardless of their background characteristics, tend to have second births. [ABSTRACT FROM AUTHOR]

The probability distribution of parity-specific closed birth intervals in a heterogeneous population of women is obtained from Biswas' (1980) concept of gradually decreasing fecundabilities. The distribution of parity-specific last closed birth intervals and its moments of various orders are derived for a heterogeneous female population. Simulations are used to compare with models for a homogeneous female population with constant fecundability. The consideration of heterogeneity allows a better fit for empirical closed birth intervals. [ABSTRACT FROM AUTHOR]

It has often been argued that there are good theoretical and historical reasons to expect that deliberate birth spacing has played an important role in fertility patterns before the demographic transition. Yet, it has proved difficult to find hard empirical evidence. In this article, we propose a new model of the speed of parity progression that includes both fixed and random effects and that efficiently captures unobserved heterogeneity between couples in fecundability and postpartum amenorrhea. With this model, we demonstrate that pre-transition couples in the Netherlands indeed spaced their births during about the first ten years of marriage. In addition, we have found strong differentials in birth intervals by socio-economic position and religion. Finally, we also show how and why the model can be used with left-censored census data. ☆ An earlier version was presented at the XXV International Population Conference (IUSSP), Tours, France, July 2005. [ABSTRACT FROM AUTHOR]

This report describes a study of the fertility experience of an Amazon Indian tribe that has shown evidence of having the highest documented fertility of any human group. The Shipibo, who live in the upper Peruvian Amazon, are experiencing rapid cultural change, including a decline in the prevalence of polygyny. This study tests the specific hypotheses that polygyny limits individual female and community fertility through the mechanism of post partum sexual abstinence and longer birth intervals. Total population counts in eight villages and reproductive histories of all females age 13 + show that mean birth interval lengths of polygynous women are four months longer than those of monogamous women. Fertility of polygynous women was lower, with 1.3 fewer term-births per reproductive span than that of monogamous women. The community general fertility rate is negatively associated with the proportion of polygynous birth intervals in the community. In this study, cultural change is strongly associated with higher fertility. [ABSTRACT FROM AUTHOR]

Scientists study seasonality in order to understand the effect of environmental, biological, and social factors on demographic events. Poor data quality can also affect seasonal variation in mortality and fertility statistics. The influence of error on seasonal data becomes crucial as researchers analyze timing and spacing of events in time-series analyses. In this study we examine the reported number of births by month in the Soviet Union for 1950, 1955, and 1958-85. The lowest number of births has typically occurred in December, and the highest in January. This seasonal pattern is not consistent with any plausible biological or behavioural explanation. It is probably an artifact of attributing births that actually occurred during the preceding December or earlier, to January. This implies that Soviet statistical practice has not followed the stated policy of attributing births to the period (day, month, year) in which they occur. A substantial reduction between the 1950s and 1985 in the December-January peak in reported births implies marked improvement in Soviet vital registration statistics. The Soviet case shows that characteristics of the registration system can impart a particular seasonal pattern to demographic data. It also shows that officially prescribed procedures are not always followed in data generation, even in centrally planned economies. Researchers should carefully examine the quality of seasonal data before concluding that the data reflect real variations in demographic behaviour. [ABSTRACT FROM AUTHOR]

Page's model of marital fertility by age and duration is fitted by maximum likelihood techniques to data from 38 of the 41 developing countries that participated in the World Fertility Survey. The results indicate that the model does an excellent job of capturing variations in fertility patterns, with only two parameters. Moreover, national-level estimates of the parameter representing the degree of control of marital fertility correlate reasonably well with the proportion using contraception. On the other hand, estimates of the parameter representing the level of natural fertility correlate well with the duration of breastfeeding and with a measure of contraceptive use for spacing, but also show substantial regional variation. The paper closes with comments on several extensions and applications of the model. [ABSTRACT FROM AUTHOR]

In this paper the question whether reproductive behaviour is consciously altered by the death of a child is answered by using World Fertility Survey data from Colombia, Costa Rica, and Korea. Alternative strategies are proposed by which women replace children who have died. They may choose to contracept for a shorter period following the death of a child, or they may cease using contraception. Each strategy is analysed separately for selected birth intervals and its effect estimated with loglinear techniques. It is found that the timing and nature of the response to child mortality appear to depend on the stage reached in a country's fertility transition. [ABSTRACT FROM AUTHOR]

This paper focuses on population dynamics which is based on birth intervals and parity progression. The parity progression model developed in this paper enables you to calculate the future population that will result from the operation of a given set of parity progression ratios and birth-interval distributions on an initial series of births distributed by order, just as the conventional method of population projection allows you to calculate the future population that will result from the operation of given age-schedules of fertility and mortality on an initial age distribution. The parity progression model embodies an approach to the measurement of fertility which is based on parity progression schedules, just as Lotka's model is based on age-specific birth rates. Parity progression schedules which incorporate parity progression rates and birth-interval distributions are arguably the most natural approach to the measurement of fertility. When people think about having children, they think in terms of whether or not and when to have a first or a subsequent birth.