Age at last birth and its components

This paper examines the ways in which the behavior of twentieth century cohorts of American women changed simultaneously in the three components of fertility that determine age at last birth--age at first birth, spacing between subsequent births, and parity progression ratios of subsequent births--to produce changes in the timing of the completion of childbearing. It decomposes changes in the mean age at last birth among cohorts and between whites and nonwhites to changes in these three components. To perform these analyses, we developed and applied a method to estimate the distributions and means of ages and last births, birth intervals, and parity progression ratios from age- and parity-specific fertility rates available from vital statistics data. Results show that the cohorts increased and decreased their age at first birth, birth intervals, and parity progression ratios of lower and higher birth orders in almost every possible combination so as to achieve a relatively young age at final birth.     

Age at marriage and timing of the first birth

Summary An attempt has been made to measure the effect of age at marriage of brides on the timing of the first birth. In Australian vital statistics, first nuptial confinements have been tabulated by age of mothers and by single years of marriage duration in single months for the first two years and by single years for all other durations since 1916. A simple technique has been used to link such data with marriage cohorts. The study briefly reviews the prevailing patterns of the timing of first births by mothers' age at marriage and changes in this pattern since the marriages of the 1925/9 period. The analysis shows that after a period of relative stability of family formation patterns in the 1950s and early 1960s, women married in the late 1960s started postponing the first birth beyond the first two years of marriage. It is suggested that a fraction of the decline in total births recorded in Australia since 1972 can be attributed to the postponement of first nuptial confinements by women married in the late 1960s and early 1970s.     

What’s happening to the age at first birth in the United States? A study of recent cohorts

This paper analyzes cross-cohort trends in the age pattern of women at first birth in the United States. The analysis involves fitting the Coale-McNeil marriage model to the age distribution of first birth frequencies for a number of recent white and nonwhite cohorts. Methodologically, the results (a) provide support for the application of the Coale-McNeil marriage model to first birth data, and (b) demonstrate the ability of the model to accurately project first birth fertility for cohorts which have yet to complete their childbearing years. Substantively the results indicate (a) that the proportion of women who will never have a first birth is increasing across cohorts and can be expected to be as high as .25 and .20 for recent white and nonwhite cohorts respectively; (b) that recent nonwhite cohorts have an appreciable number of first births at earlier ages than their white counterparts, as well as a lower mean age at first birth and increasingly less dispersion (across cohorts) in their age at first birth; and (c) that the mean age at first birth and the proportion of first births occurring between ages 25 and 34 is increasing across cohorts of white women but is stable across cohorts of nonwhite women.     

A cohort analysis of the timing of first birth and fertility in Ghana

This paper examines the nature of the inverse association between age at first birth and fertility across successive generations of Ghanaian women. Within the context of enhanced non-marital opportunities for contemporary women and declining fertility, we develop a rationale for and test the hypothesis that in a medium fertility environment as currently found in Ghana, the effect of age at first birth on fertility becomes more important than ever before. Five birth cohorts were identified (1938–1944; 1945–1949;1950–1954; 1955–1959; 1960–1964)from a merged file of the 1988, 1993 and 1998 Ghana Demographic and Health Surveys. The analyses were restricted to women over 35 years old at the time of the surveys, which allowed us to use current parity as a reasonable proxy for completed fertility. Preliminary results suggest that women who had first births early tend to have a higher number of births than those whose first births occur late, regardless of birth cohort. In multivariate analyses, the effect of age at first birth as a determinant of fertility was found to be more substantial among later cohorts. The implications of the findings are discussed.     

Fertility of Australian birth cohorts: Components and differentials

The paper examines the change in the level and pattern of fertility that took place in the post-1971 period, and the downward completed fertility of successive generations of Australian women born since 1933–37. The change in cohort fertility is assessed in terms of the cohort parity progression ratios, and the four components of cohort total fertility: the proportion of women who proceeded to have a birth, mean age at first birth, mean age at last birth, and average interbirth interval for women who had at least two births. The other aspects discussed are the cohort fertility differentials and the implications of the current trends for future fertility in Australia.     

The Demographic Promise of Expanded Female Education: Trends in the Age at First Birth in Malawi

The expansion of female education has been promoted as a way to postpone the age at first birth. In sub‐Saharan Africa, the first cohorts to benefit from policies that expanded access to education are now reaching adulthood and beginning childbearing. I investigate whether the expansion of education in Malawi, which implemented a free primary education policy in 1994 and subsequently expanded secondary schooling, has led to a later age at first birth and whether the education gradient in fertility timing has remained stable over time. Despite increases in female grade attainment over the past twenty years, the age at first birth has not changed. Using instrumental variables analysis, I find a significant negative association between grade attainment and age at first birth, suggesting that the deterioration of school quality and the shift in the age pattern of enrollment that accompanied educational expansion may have compromised the transformative potential of education.     

Childbearing Across Partnerships in Australia,the United States,Norway, and Sweden

This article compares mothers’ experience of having children with more than one partner in two liberal welfare regimes (the United States and Australia) and two social democratic regimes (Sweden and Norway). We use survey-based union and birth histories in Australia and the United States and data from national population registers in Norway and Sweden to estimate the likelihood of experiencing childbearing across partnerships at any point in the childbearing career. We find that births with new partners constitute a substantial proportion of all births in each country we study. Despite quite different arrangements for social welfare, the determinants of childbearing across partnerships are very similar. Women who had their first birth at a very young age or who are less well-educated are most likely to have children with different partners. The educational gradient in childbearing across partnerships is also consistently negative across countries, particularly in contrast to educational gradients in childbearing with the same partner. The risk of childbearing across partnerships increased dramatically in all countries from the 1980s to the 2000s, and educational differences also increased, again, in both liberal and social democratic welfare regimes.     

Cohort disaggregation analysis of fertility data from a sample survey

Social differentials in cumulative fertility revealed by field surveys in a number of countries typically have been interpreted with the implicit assumption that the timing of childbearing within the reproductive period remains constant. However, the reproductive histories that have been collected in such surveys provide a largely unexploited source of data for the analysis of trends in timing. An analysis by birth cohort of the fertility experience of 592 ever-married women surveyed in San Juan, Puerto Rico, in 1966 shows that significant changes in timing have occurred. Women in the more recent birth cohorts are distinguished by earlier childbearing and sustained higher fertility in consecutive age periods. The inter-cohort differences remain when adjustments are made for duration of time in legal and consensual unions.     

Proximate determinants of Philippine fertility: 1983 levels and patterns

Data from the 1983 National Demographic Survey are used to analyze the proximate determinants of Philippine fertility in each of the 3 stages of family formation and to identify all of the direct and indirect factors affecting fertility levels and trends. 10,843 ever-married women and 12,771 children were included. The analysis pertains first to the starting patterns of family formation, the age at first birth, and the proximate determinants (age at menarche, age at first marriage/union, conception before first birth, fetal wastage first birth, interval between first marriage and first birth). Further analysis examines birth spacing patterns including the postpartum nonsusceptible period, the exposure interval and stopping patterns. Almost all births occur within marriage, and childbearing begins late at 22.5 years. However, 15.4% of first births are conceived premaritally. The mean age at first birth increases from younger to older cohorts. Urban women were slightly older (23.0 years) at the birth of their first child. Those with education below the 4th grade had first births 3.5 years earlier. Contraceptive use was low at 1.8% before first birth. Younger cohorts were more likely to use birth control and urban wives were more likely to use it than rural wives. 6.4% reported a first pregnancy ending in nonlive births, which were primarily spontaneous abortions (5.2%), stillbirths (1.0%), and induced abortions (.2%). 5.8% report never having been pregnant and 1.1% never having given birth to a live-born child. 20.4% were childless between the ages of 15-24 years, and 4.6% between 25-34 years. Childlessness was slightly higher among urban women (7.1%) than rural women (6.7%). A decreasing age at menarche has appeared; i.e., 13.6 years for the cohort 15-24 years, and 14.0 for the oldest cohort. By age 15, 82.9% had begun menstruating. The mean age at marriage is early at 20.7 years, and older cohorts tended to marry later at 21.4 years. Urban women marry a year later (21.4 years) than rural women. Lower educated women marry 4 years earlier. The mean length between first marriage and first birth was 18.4 months. In the younger cohorts, spacing patterns are shorter. Postpartum susceptibility is short. Return to sexual relations after a birth occurred at 2.8 months. The exposure time required to conceive is fairly long at 16.6 months and is attributed to contraceptive use, since coital frequency is high and temporary separation is infrequent. The average age at last birth is late at 37.6 years.     

Baby boomlet for older mothers?

In recent years, a number of celebrities have begun childbearing after age 35. The phenomena of older first-time mothers has received a great deal of attention in the popular press. Are these celebrities indicative of a national trend? Does the increase in fertility portend a reversal of the declines in fertility which have been occurring since the baby boom? The present paper uses central and cumulative birth rates for cohorts of American white women born between 1882 and 1953 to investigate childbearing between ages 35 and 50. While there has been a noticeable upsurge in first birth rates for cohorts in their mid to late 30s in recent years, overall central birth rates for women in their 30s are among the lowest on record, with cumulative birth rates at record low levels. A major reason for this is that these women are having relatively few third and higher order births. These cohorts will need to have a relatively high proportion of births in their older years of childbearing in order to reach replacement level. However, attaining replacement level is unlikely because such a high proportion of women have remained childless at ages 35–40 and a relatively low proportion are having three or more children.     

Diverging fertility among U.S. women who delay childbearing past age 30

In this paper I examine the evolving association between educational attainment and the timing of births. In the late 1970s, women with four-year college degrees had lower first birth rates before age 30 than women with less education, but rates of first births were similar for the two groups after age 30. From the 1970s to the 1990s, first birth rates decreased before age 30 for all women, but increased after age 30 only for women with four-year college degrees. Parity 2 birth rates also increased for college graduates with a first birth after age 30. These results document widening educational differences in fertility timing between 1975 and 1995, which may reflect period changes at later ages in women's work and family lives.     

The Changing Pattern of Educational Differentials in Divorce in the Context of Gender Egalitarianization: The Case of Taiwan

Regarding educational differentials in divorce, similar trends have been reported across countries. Some report increasing educational differentials, while others identify an educational crossover pattern. The commonality is that education seems to play a role of stabilizing marriage more than ever before. Using data from the Women??s Marriage, Fertility, and Employment Survey, this study investigates the case of Taiwan by portraying the changing pattern of women??s educational differentials in divorce. There are three major findings. First, among previous marriage cohorts, women with relatively higher levels of formal education are significantly more likely to divorce. Second, the marital-dissolution rates for less educated women are rising faster than the corresponding rates for women with more education. Third, this trend does not stop at the catch-up point and eventually leads to a reversal in the association between education and divorce from positive to negative. In short, such educational differentials in divorce vary dramatically across marriage cohorts. A pattern of educational crossover in divorce has been displayed during the rapid social change in Taiwan. Other than William Goode??s argument raised a half-century ago, the marriage model transformation from specialization toward symmetry in the context of gender egalitarianization has to be taken into consideration in order to obtain a full understanding of the phenomenon.     

The temporal relationship of marriage,conception, and birth in Massachusetts

An investigation into the timing of first births in relationship to the date of marriage in Massachusetts confirmed the finding of previous national and local birth timing studies that first births likely to have been conceived before the marriage of their parents constitute a substantial proportion of all first births. The differential frequency of premaritally conceived births among various subgroups appeared to account for the variation noted in the overall timing patterns of first births after marriage. Data were gathered through linkage of certificates of birth of a sample of legitimate first children with the marriage record of their parents. Analysis of the marriage-first birth interval by maternal age and race, type of marriage ceremony, and occupation of the bride and groom were conducted and comparisons with previously published data were made. Separate consideration was given to the frequency and characteristics of those births likely to be premaritally conceived and those likely to have been conceived after the wedding.     

Intergenerational transmission of age at first birth in the Netherlands for birth cohorts born between 1935 and 1984: evidence from municipal registers

Whereas most research on the intergenerational transmission of fertility behaviour has focused on transmission of the number of children, this paper studies the transmission of the timing of first births. Specific attention is paid to changes in the strength of transmission across cohorts. Theoretically, it is unclear whether the strength of intergenerational transmission of entry into parenthood can be expected to increase or to decrease across cohorts. Event history analyses of data in Dutch registers show a substantial degree of intergenerational transmission in the age at which people have their first child. The degree of transmission from mothers to children increases for successive cohorts. Intergenerational transmission becomes weaker the longer children postpone entry into parenthood. At young ages transmission from mothers to children is stronger than from fathers to children.     

The third birth in Sweden

This paper considers the formulation, estimation and interpretation of microdynamic models of fertility. Our model explains parity choices, sterility, childlessness, interbirth intervals and initiation of pregnancy within a unified framework. We develop a general methodology for estimating the determinants of transition times to births of different orders. Our procedure incorporates time-varying explanatory variables and unobservables. We present conditions that justify conventional formulae relating hazards to survivor functions when time-varying variables enter hazards. We also consider the validity of widely-used piecemeal estimation strategies that focus on one birth at a time. We consider methods for selecting a best model among a class of non-nested models. Two criteria are set forth and used to evaluate the detminants of third births in Sweden.We find that two models fit Swedish microdata equally well. One model is consistent with neoclassical economic theory. It assigns a central role to the wages of men and women in explaining the timing and spacing of births. The other model is purely demographic and excludes wages. Purely statistical criteria cannot distinguish these models although in other work we show that the economic models are more parsimonious in terms of the number of parameters that must be estimated and are better able to forecast aggregate time series.We demonstrate how to interpret the output of multistate fertility models. Wage effects on third births are decomposed into two components: (a) an in direct effect that determines whether a woman is at risk to have a third birth, and (b) a direct effect on the transition rate to the third birth given that a woman has had two births. We find that female wages play an important role in postponing first births but play only a minor role in explaining childlessness. Female wages substantially affect third births. Male wage effects are weaker. We find that female wage effects weaken for more recent cohorts of women. This evidence is consistent with the introduction of progressively more pronatal Swedish policies.This research was supported by NIH Grant No. HD-19226 to NORC. We have benefited from the comments of Elja Arjas and Ricardo Barros. This paper was presented at an IUSSP Conference in Paris, France, in March 1988, and as an invited lecture at the Fourth ESPE Meetings in Istanbul, Turkey, June, 1990. This paper is one part of a trilogy. Heckman and Walker (1990a) presents a succinct summary of the main economic results. Heckman and Walker (1990b) presents a more complete discussion of the empirical results. This paper presents a more purely demographic discussion.     

Starting age and subsequent birth intervals in cohabitational unions in current danish cohorts, 1975

This paper presents some main results of an investigation by life table methods of birth interval data in cohabitational unions (marriages as well as consensual unions) in current Danish cohorts. Our results confirm previous findings that an early age at the start of recorded exposure to childbearing risk is indicative of a rapid pace and high level of subsequent fertility. The analysis modifies previous results and adds several new details regarding cohort trends and the effect of parity at the start of reported cohabitation. For each parity within a period of cohabitation, fertility differentials by reported starting age seem to have diminished from our older cohorts (of age up to 49 years in 1975) to our younger ones (of age less than 30 years in 1975). There are indications of a dramatic change in childbearing behaviour following the arrival of novel attitudes to non-marital cohabitation and childbearing in Denmark about 1967.     

Stabilization,birth waves,and the surge in the elderly*

Substantial regularities characterize the transition to stability that follows a shift from one set of vital rates to another. The new vital, rates interact with the population's initial age composition and generate birth waves whose amplitude and attenuation depend on the ratio of ultimate to initial growth and on the new pattern of stable net maternity. A greater change in growth and a later stable net maternity pattern produce larger fluctuations in the number of births. Stabilization begins at the youngest ages and proceeds upward. Sixty years after the shift, the birth waves have largely disappeared and the proportion under age 15 approximates the stable level implied by the new rates. Those patterns are manifest in the stabilization of both observed and Coale‐Demeny model stable populations.

When fertility falls, the new stable population has a larger fraction at all ages above (approximately) 30, with greater changes characterizing the extremes of life. Fifteen years after the fall, there is a trough in the number at ages 0–14. Sixty years after the fall, when the largest pre‐decline cohort is age 60–74 and the smallest post‐decline cohort is age 45–59, there is a surge in the relative size of the elderly population. Thus after two generations, the birth waves produced by a rapid decline in fertility accentuate the effects of population aging.     

The negligible influence of premarital cohabitation on marital fertility in current danish cohorts, 1975

This paper studies the influence of premarital cohabitation on marital fertility by applying life table methods to data for cohorts of Danish women born in 1926–1955, collected in retrospective interviews made in 1975. For each five-year cohort, the data have been analyzed by duration of marriage or by duration since previous birth, for women who had no reported births before marriage. Our main empirical results are: (a) that women who married at age 15–19 had higher rates of marital first and second births than those married at ages 20–24, and (b) that premarital cohabitation had very little influence on births of these two first orders in our data.     

White and nonwhite trends in first birth timing: Comparisons using vital registration and current population surveys

The magnitude of racial differences in first birth timing vary greatly depending upon the data sources from which they are estimated. Vital registration data (Heuser 1976; with updates from the National Center for Health Statistics 1974–1990) show that in recent years nonwhites have higher risks of a first birth at virtually all ages compared to whites. As a result very large and historically novel differentials in childlessness are forecast using these data (see Rindfuss et al. 1988; Chen & Morgan 1991; Morgan & Chen 1992). However, retrospective fertility history data collected from the 1980, 1985 and 1990 Current Population Surveys (CPS) suggest much smaller racial differences in completed childlessness and isolate racial differences in probabilities of first births at young ages. Differences also exist between theses two series for whites prior to the mid-1960s but not afterwards. Reasons for these differing estimates are suggested and examined. We conclude that a substantial portion of the differences result from an accumulation of biases in the vital registration estimates that affect primarily estimates of first birth timing. Thus, the CPS data provide a more firm basis for racial comparisons of first birth timing.     

Schooling,marriage, and age at first birth in Madagascar

The low school attainment, early marriage, and low age at first birth of females are major policy concerns in less developed countries. This study jointly estimated the determinants of educational attainment, marriage age, and age at first birth among females aged 12–25 in Madagascar, explicitly accounting for the endogeneities that arose from modelling these related outcomes simultaneously. An additional year of schooling results in a delay to marriage of 1.5?years and marrying 1?year later delays age at first birth by 0.5?years. Parents’ education and wealth also have important effects on schooling, marriage, and age at first birth, with a woman's first birth being delayed by 0.75?years if her mother had 4 additional years of schooling. Overall, our results provide rigorous evidence for the critical role of education—both individual women's own and that of their parents—in delaying the marriage and fertility of young women.