S. Philip Morgan

Is Low Fertility a Twenty-First-Century Demographic Crisis?

Nearly half of the world’s population in 2000 lived in countries with fertility rates at or below replacement level, and nearly all countries will reach low fertility levels in the next two decades. Concerns about low fertility, fertility that is well below replacement, are widespread. But there are both persistent rationales for having children and institutional adjustments that can make the widespread intentions for two children attainable, even in increasingly individualistic and egalitarian societies.Nearly half of the worlds population in 2000 lived in countries with fertility rates at or below replacement level, and nearly all countries will reach low fertility levels in the next two decades. Concerns about low fertility, fertility that is well below replacement, are widespread. But there are both persistent rationales for having children and institutional adjustments that can make the widespread intentions for two children attainable, even in increasingly individualistic and egalitarian societies.

First births in America: changes in the timing of parenthood.

Americans today are becoming parents at older ages; more of them are also remaining childless. This book addresses what causes some members of the population to choose delay or permanent childlessness how far they pervade American society and how their parenthood schedules compare with those in other developed countries. The authors bring a wide variety of data sources to bear on the question of whether these delays will be greater and permanent childlessness more widespread in the future; they employ vital registration data cross-sectional studies and longitudinal surveys. It is concluded that few young Americans intend to remain childless but that the competition of educational and career goals and the presence of unfavorable economic conditions lead to postponement of childbearing. Similar parenthood schedules were recorded during the Great Depression. The authors refute the prediction that present trends will continue in the future. Strong period effects have occurred and are likely to occur again; they are unpredictable by their very nature. Although period changes in parenthood timing appear to affect virtually all sectors of the American population there are also important exceptions. Recent divergence between white and black behavior is 1 and the persistence of very early parenthood in both good and poor times is another. Contrasts with Japan show that the parenthood schedules of contemporary Americans are not an inevitable outcome of the forces of economic development and modernization. Rather the American pattern is 1 possible response that is consistent with its culture institutions and past history.

Logistic Regression: Description, Examples, and Comparisons.

Family studies have seen a dramatic increase in the use of statistical tools for the analysis of nominal-level variables. Such models are categorized as log-linear models often known as logit models or logistic-regression models. Despite logistic regressions growing popularity there is still confusion about the nature and proper use in family studies. The authors present a nontechnical discussion of logistic regression with illustrations and comparisons to better-known procedures such as percentaging tables and ordinary least squares regression. They contend that logistic regression can be a powerful statistical procedure when used appropriately. Nominal-level dependent variables are common in family research and logistic-regression models appropriately model the impact of predictor variables on these outcomes. With the proliferation of computer software for estimating logistic-regression models use of logistic regression is likely to increase. Though some time and attention is required to master it the advantages of logistic regression make the effort worthwhile.

Marital disruption: structural and temporal dimensions

Relying heavily on Ryders (1965) argument concerning the central role of cohorts in social change and on Elders (1978) work on life cycles, this paper integrates the disparate threads of the current marital disruption literature and provides an integrated framework for subsequent analysis. We focus on the study of intracohort life cycle development and comparative cohort careers. Our framework incorporates both elements simultaneously. Using 1980 Current Population Survey data and conditional logit analysis, this framework allows us to make refined statements about which marriage cohorts are most affected by given variables and where within the cohorts life cycle they act. For instance, we show that both the timing of the marriage and maritally conceived births affect the likelihood of disruption in all cohorts and at all marital durations observed. In contrast, the wifes level of education and a premarital birth affect the likelihood of marital disruption only at early marital durations. Such variable patterns of effects along the temporal dimensions of cohort and duration provide important clues to the mechanisms by which these variables influence marital disruption.

The Relationship between Early Childhood Blood Lead Levels and Performance on End-of-Grade Tests

Background Childhood lead poisoning remains a critical environmental health concern. Low-level lead exposure has been linked to decreased performance on standardized IQ tests for school-aged children. Objective In this study we sought to determine whether blood lead levels in early childhood are related to educational achievement in early elementary school as measured by performance on end-of-grade (EOG) testing. Methods Educational testing data for 4th-grade students from the 2000–2004 North Carolina Education Research Data Center were linked to blood lead surveillance data for seven counties in North Carolina and then analyzed using exploratory and multivariate statistical methods. Results The discernible impact of blood lead levels on EOG testing is demonstrated for early childhood blood lead levels as low as 2 μg/dL. A blood lead level of 5 μg/dL is associated with a decline in EOG reading (and mathematics) scores that is roughly equal to 15% (14%) of the interquartile range, and this impact is very significant in comparison with the effects of covariates typically considered profoundly influential on educational outcomes. Early childhood lead exposures appear to have more impact on performance on the reading than on the mathematics portions of the tests. Conclusions Our emphasis on population-level analyses of children who are roughly the same age linked to previous (rather than contemporaneous) blood lead levels using achievement (rather than aptitude) outcome complements the important work in this area by previous researchers. Our results suggest that the relationship between blood lead levels and cognitive outcomes are robust across outcome measures and at low levels of lead exposure.

Why Have Children in the 21st Century? Biological Predisposition, Social Coercion, Rational Choice*

This review examines arguments and evidence pertaining to the question: why have children in settings where the net economic costs of children are clearly substantial? Thereview is organized around three themes: biologicalpredispositions, environment (social coercion) and rationalchoice. Specifically, we explore the argument that evolution hasproduced sets of genes that predispose persons to childbearing bymaking sex and parenthood pleasurable. We review sociologicalarguments regarding the pronatalism/antinatalism of societalinstitutions. Finally, we discuss arguments that stress therationality of childbearing decisions by appealing to biologicalpredispositions and the economic and non-economic values ofchildren. The authors speculate that while a modern socialstructure and rationale supportive of childbearing could beconstructed, such changes are not inevitable and may be difficultin the face of competing interests. Moreover, future social andtechnological change could alter the context of childbearingsubstantially. This uncertainty complicates policyrecommendations.

CHILD CARE AVAILABILITY AND FIRST-BIRTH TIMING IN NORWAY

Both sociological and economic theories posit that widely available, high-quality, and affordable child care should have pronatalist effects. Yet to date, the empirical evidence has not consistently supported this hypothesis. We argue that this previous empirical work has been plagued by the inability to control for endogenous placement of day care centers and the possibility that people migrate to take advantage of the availability of child care facilities. Using Norwegian register data and a statistically defensible fixed-effects model, we find strong positive effects of day care availability on the transition to motherhood.

Women's Work, Autonomy, and Birth Control: Evidence From Two South Indian Villages

In this study we contrast two South Indian villages which offer women very different employment opportunities. Many women in Village I roll beedis, which are crude hand-rolled cigarettes. The structure of beedi work was designed to meet the needs of the beedi contractor, but inadvertently it has provided women with substantial autonomy. In Village II very few women work for pay. We argue that these different employment opportunities affect womens autonomy, which in turn influences important demographic outcomes. More precisely, we argue that greater autonomy will increase contraceptive use among women who want no more children. We find strong support for this hypothesis. But, because there are few competing employment opportunities in Village II, women in that Village have received substantially more education than those in Village I. This higher level of education is also associated with greater contraceptive use. Thus, overall, the level of contraceptive use does not vary greatly between villages. More...

EMERGING PARENTAL GENDER INDIFFERENCE? SEX COMPOSITION OF CHILDREN AND THE THIRD BIRTH.

For much of the twentieth century, parents in the United States with two children of the same sex were more likely to have a third child than were parents with one son and one daughter, that is, there was an effect of the sex of previous children on the occurrence of a third birth. Using multiple cycles of the Current Population Survey and National Survey of Family Growth, the authors examine the strength of this effect on both fertility behavior and intentions over multiple decades. Changes in the societal gender system are expected to weaken this pronatalist effect in recent periods. Consistent with this expectation, there has been some attenuation of the effect of sex composition of previous children on the third birth, suggesting declining salience of childrens gender for parents.

Intergenerational Fertility Among Hispanic Women: New Evidence of Immigrant Assimilation

In recent decades, rapid growth of the U.S. Hispanic population has raised concerns about immigrant adaptation, including fertility. Empirical research suggests that Hispanics, especially Mexicans, might not be following the historical European pattern of rapid intergenerational fertility decline (and convergence toward native levels). If confirmed, continued high Hispanic fertility could indicate a broader lack of assimilation into mainstream American society. In this paper, we reexamine the issue of Hispanic and Mexican fertility using an approach that combines biological and immigrant generations to more closely approximate a comparison of immigrant women with those of their daughters’ and granddaughters’ generation. Contrary to cross-sectional results, our new analyses show that Hispanic and Mexican fertility is converging with that of whites, and that it is similarly responsive to period conditions and to women’s level of education. In addition, we employ a mathematical simulation to illustrate the conditions under which cross-sectional analyses can produce misleading results. Finally, we discuss the import of the fertility convergence we document for debates about immigrant assimilation.