Family size may be considered from two perspectives. At the individual (micro) level, it defines one aspect of an individual's family background or environment. As such, it represents a potential influence on the development and accomplishments of family members. At the societal (macro) level, family size is an indicator of societal structure that may vary over time, with concomitant implications for individual development and social relations in different cohorts. In this essay, consideration is given to both aspects of family size, as it is reflected in sociological theory and research.
While the term family size is sometimes used to represent the total number of individuals comprising a family unit, Treas (1981) argues convincingly for decomposing the concept into two components: numbers of children and numbers of adults in the household. This distinction is important, as observed patterns of change in overall family size may be attributable to one component or the other, as may effects of overall family size. In the present discussion, family size is defined in terms of the number of children in the household.
A further distinction is made between family size in the parental and filial households, sometimes referred to as the family of origin (or orientation) and the family of procreation. Some use the term sibship size to refer to the number of children in an individual's parental family (Blake 1989; Ryder 1986). However, the two are not directly comparable: Mean family size takes into account those families which have no children, while mean sibship size is necessarily restricted to families with children.
Family size can also be differentiated from fertility, which reflects the aggregate numbers of births relative to the numbers of women in the population, without regard for the distribution of those births across family units. Fertility and family size are both important characteristics of cohorts; however, for assessing relationships at the individual level, family size or sibship size is the more meaningful construct (Ryder 1986).
The subsequent sections address the following aspects of family size: demographic trends in family size, antecedents and correlates of family size, and implications of sibship size and family size for child and adult members of the family.
The twentieth century has witnessed substantial change in both fertility and family size (as indicated by the number of children in the household), with the overall trend being toward smaller families. Such trends can be examined through comparisons of fertility rates and mean family size, and also through investigation of parity distributions—that is, the numbers of families with zero, one, two (and so on) children.
Drawing on fertility tables compiled by the National Center for Health Statistics, Ryder (1986) presents time-series data for successive cohorts of women in the United States born between 1867 and 1955 (and who would thus be bearing children between approximately 1885 and 1975) that show the following general trends in fertility and family size:
- Total fertility declined by 52 percent in the period being considered, from 4.00 for women born in 1867–1870 to 1.92 for women born in 1951–1955. A similar rate of decline occurred in marital fertility.
- This decline was punctuated by a temporary upsurge in fertility for women born in 1916–1940, who were bearing children during the two decades following World War II (the "baby boom" years).
- Variation in fertility rates increased for cohorts through 1910 and since then has consistently decreased, suggesting that in recent years there have been fewer women bearing no children or large numbers of children and an increasing concentration of families of moderate size.
- Family size (the mean number of children in the family) decreased by 61 percent from a high of 7.3 for women born in 1867–1870 to 2.8 for women born in 1951–1955.
It thus appears that during the period under consideration, mean family size decreased at an even faster rate than fertility. Further, the increased fertility during the baby boom years appears to have been offset by reduced variation in fertility for those cohorts of women, with the result that mean family size held relatively constant during that period, then continued its pattern of decline.
Treas (1981) examined changes in family size between 1955 and 1978 for whites and for nonwhites, using data from the March Current Population Surveys. Throughout the period, nonwhites consistently had larger families than did whites: In 1955 the mean number of children was 1.26 in white families and 1.80 in nonwhite families; in 1978 the corresponding figures were 1.04 and 1.56. During this period Treas found similar patterns of increases in family size through the 1960s, followed by decreasing family size in the 1970s, for both groups. However, the shifts were considerably more pronounced among nonwhite families.
Data obtained from the U.S. Census on the distribution of family sizes (parity distributions) provide further insight on the trend toward smaller families. During the years between 1970 and 1988 the proportion of families with no children under eighteen increased substantially, from 44 percent to 51 percent, while the proportion of families with one child or two children increased only slightly (from 18 percent to 21 percent and from 17 percent to 18 percent, respectively). However, the proportion of families with three or more children decreased markedly, from 20 percent to 10 percent during this period. Among black and Hispanic families, the increase in families with no children was not as pronounced as among white families, but the increases in families with one or two children were greater, as were the decreases in families with three or more children (U.S. Bureau of the Census 1990, p. 51).
Further insight into the decline in family size is provided by investigations of parity progression, or the probability of having (or intending to have) an additional child at each parity level. Decomposing his time-series data into parity progressions, Ryder (1986) reports that the baby boom was the result of an increase in progression from parities one and two, but that progression from parities three and higher have shown consistent declines. Similarly, data on intended parities show that the proportions intending progression from parity one have increased over time, while the intended progression ratios for parity three and higher have declined.
Other data on ideal, or normative, family sizes support this pattern of increasing concentration of smaller families. West and Morgan (1987) cite historical data showing that fertility norms have fluctuated in parallel with fertility rates and family sizes: During the 1930s and early 1940s two- and three-child families were preferred. During the post–World War II era three- and four-child families became the ideal, but in the late 1960s preferences reverted to the two- or three-child family. They further report that, among a sample of contemporary adults, a significant majority (64.8 percent) view the two-child family as ideal; that belief was surprisingly consistent across various subgroups defined by current family size, marital status, race, and religion.
At the same time that families have tended to become smaller on average, there has been increased variability in the timing of childbearing. One trend that has been widely noted has been the increase in childbearing among teenagers, particularly among those who are of lower socioeconomic statues (SES), nonwhite, and less academically able youth (Card and Wise 1978). At the same time, there has been an increase in the proportion of women who delay childbearing until their early and mid-thirties or who remain childless (Bloom and Trussell 1984). As will be discussed below, the timing of the first birth has implications for the eventual family size and thus for the development and accomplisment of family members.
In sum, in the United States there appears to have been a strong shift toward smaller families, with the ideal being a two- or three-child family. A similar trend toward smaller families is found in other developed countries, while in developing countries families are more likely to be larger (Lopreato and Yu 1988). One exception to this generalization concerns countries, such as the People's Republic of China, that are trying to implement a policy of restricting families to one child. However, while the policy appears to have led to lower mean family sizes, numerous families have continued to have two or more children, and a preferred family size of two continues to be the mode (Whyte and Gu 1987).
ANTECEDENTS AND CORRELATES OF FAMILY SIZE
Determinants of family size have been investigated at both the societal and the individual level. At the societal level, researchers have sought to account for differences in fertility and family size over time or between societies. Easterlin (1980) advanced the theory that changes in fertility and family size over time are a function of individuals' economic resources and aspirations. He attributes the baby boom surge in fertility and family size to the generation of young men following World War II who experienced high wages, as a result of the expanding economy, and had relatively low material aspirations, as a result of being raised during the Depression. Conversely, the baby boom generation confronted increased competition for jobs, which, combined with higher aspirations, led to the "baby bust" of the 1970s and 1980s. One implication of Easterlin's theory is that smaller birth cohorts are likely to experience more favorable labor markets, resulting in higher fertility.
A variation of this theory is espoused by Devaney (1983), who argues that the decline in fertility observed during the 1960s and 1970s can be attributed to increases in female wages and female employment, which in turn served to depress fertility, rather than to conscious decisions to limit fertility in the face of disadvantageous economic conditions. Her analyses, based on national fertility data and data on female labor-force participation rates and male and female earnings, suggest (1) that female labor-force participation and fertility are highly and negatively correlated and (2) that female wage rates are the dominant factor in explaining recent variations in fertility and female employment. While this model differs from Easterlin's in terms of the process by which economic factors are thought to influence fertility, they are similar in viewing fertility as a response to economic market conditions.
Studies of developing countries have focused on several sociocultural as well as socioeconomic factors associated with fertility and family size: modernization (Levy 1985); contraceptive use and family-planning programs (Koenig et al. 1987); and cultural attitudes and values, such as the perceived old-age security value of children (Rani 1986) or the view of children as risk insurance (Robinson 1986).
At the individual level, researchers have examined the extent to which fertility and family size may vary depending on individuals' family backgrounds, social and psychological characteristics, or economic status. Inverse relationships between social class and family size have been documented in a number of data sets: Individuals from larger families tend to have less-well-educated fathers who have lower-status occupations. Also, farm background is associated with larger family sizes (Blake 1989).
Parents' sibship size (the number of siblings that each parent had) is a second major determinant of family size: Women and men from larger families are more likely to have larger families (Ben-Porath 1975; Thornton 1980). This gives rise to an apparent paradox: While there is an overall trend toward small families, a high proportion of children come from larger families (Blake 1989). This paradox arises from the distinction noted above between cohort fertility rates, which are based on all women or all families, and children's sibship sizes, which are necessarily limited to women or families who have had children.
Retherford and Sewell (1988) investigated the relationship between intelligence and family size in their analysis of data from the Wisconsin Longitudinal Study of the High School Class of 1957, finding that the overall relationship between IQ and family size was negative for both sexes. However, the relationship proved to be much stronger for females, who showed consistent declines in family size as IQ increased. Among men the relationship was less consistent. Retherford and Sewell also reviewed the results of other, earlier studies, noting that the negative relationship between IQ and family size appears to have become more pronounced in the post–baby boom cohorts.
Additional factors associated with family size pertain primarily to family and achievement-related characteristics of the mother: More education, later age at marriage, longer interval between marriage and the birth of the first child, and employment status are all associated with smaller families—that is, fewer children (Wagner et al. 1985). Family configuration has also been found to be associated with increased family size, with the probability of having an additional child being higher in families with all children of the same sex (Gualtieri and Hicks 1986). Also, only children are disproportionately likely to come from broken families (Blake 1989).
The interaction between wives' employment and childbearing has been a topic of much study, as women have increasingly entered or remained in the work force, but the results obtained are inconsistent. Waite and Stolzenberg (1976) found a significant negative relationship between wife's work and family size. However, based on analyses of longitudinal data that allowed for the study of recursive processes as well as inclusion of several additional measures, Bagozzi and Van Loo (1988) found no causal relationships between wife's employment and family size; they suggested that both labor-force participation and family size are codetermined by the wife's achievement motivation, sex-role norms, and perceived value of children.
Oropesa (1985) used data from the National Opinion Research Center (NORC) General Social Surveys to test the hypotheses represented in Easterlin's model at the micro level, using relative affluence as the predictor and expected family size as the outcome of interest. He found that relative affluence is more likely to be associated with expected births for women than for men, and that the effects are stronger with regard to expected births in the short term than with total expected family size.
The research cited above focuses on static determinants of childbearing and family size. However, some investigators have examined fertility and childbearing decisions as a dynamic process, influenced by life situation and life events, that may change over time, as well as by relatively fixed individual characteristics. One line of investigation has focused on timing of first birth as a determinant of eventual family size. Card and Wise (1978) and Hofferth and Moore (1979) demonstrated that early first births are associated with larger families; Bloom and Trussell (1984) similarly demonstrated that delayed childbearing is associated with smaller average family sizes, as well as with childlessness.
A second line of research has investigated the relationships between parity level and fertility decisions. Udry (1983) examined the relative influence of initial fertility plans and intervening life events (such as births during the interval, change in household income, change in education, female work status, change in marital satisfaction) on couple's fertility decisions at different parity levels. He found that including intervening events in the analyses improved the prediction of both fertility plans and, especially, actual fertility behavior, providing support for a sequential model of fertility decision making. White and Kim (1987) investigated whether the determinants of fertility choices vary by parity; they found a nonlinear relationship between fertility determinants and childbearing, especially with regard to factors related to women's roles. Both sex-role traditionalism and achievement in nonfamily roles were associated with a higher probability of having a child at parity zero or one, but a lower probability of having a child among women at higher parities. These findings are somewhat contrary to those based on cross-sectional analyses of family size, suggesting the importance of taking parity level into account in such investigations.
IMPLICATIONS OF SIBSHIP AND FAMILY SIZE
The effects of sibship/family size and family composition on children and on adults has long been a topic of popular interest and in recent years has become the focus of a considerable body of sociological and psychological inquiry. In particular, attention has been directed to effects of sibship size on children's cognitive development, physical and social-psychological development, educational attainment, and socioeconomic attainment and mobility. Consideration is also given to effects of family size on parents and on family well-being.
Cognitive Development. Interest in the relationship between sibship size and intelligence dates back to Anne Anastasi's (1956) review, which found an inverse relationship between the two. Subsequent empirical studies, in the United States as well as in Europe, using various measures of ability and controlling for family background characteristics, have confirmed this finding (Belmont and Marolla 1973; Breland 1974; Claudy et al. 1974). Blake (1989) provides a comprehensive review of this literature, including a discussion of limitations and weaknesses in the prior studies.
Only children present a special case. Numerous studies have reported that only children do not perform as well on intelligence measures as do children from two-child families. Indeed, in the Belmont and Marolla study (1973), only children were found to be lower in intelligence than firstborns in families up to size four, and lower than second-borns in families up to size three. Claudy and associates (1974) obtained similar results after controlling for differences in SES. However, when differences in family composition were taken into account by restricting the sample to only children in two-parent families, the differences between only children and first-born children in larger families became nonsignificant (Claudy et al.1979).
In an effort to account for the observed relationships between sibship size and intellectual ability, Zajonc (1976) introduced the "confluence model," which postulates that the intellectual environment in the home, defined by the combined intellectual levels of the parents and children, accounts for the observed relationships. According to his theory, the intellectual level is at its peak in families with two adults and no children; as the number of children in the home increases, the intellectual environment afforded to any individual child is effectively diluted. There are two implications of the "confluence model": Children from smaller families should show higher intelligence, and children born earlier in families should show higher intelligence. While the former hypothesis has been supported by a number of empirical studies, the latter did not account for the findings pertaining to only children. In response, Zajonc expanded the confluence model, postulating that younger siblings provide an opportunity for teaching, thus enriching the intellectual experience of older children; the lower intellectual performance of only children is attributed to the fact that they cannot avail themselves of this opportunity. While the confluence model has generated considerable discussion and debate, particularly regarding possible interactions between family size and birth order, and with family SES (for example, see Steelman 1985; Zajonc 1986), a systematic test of the model remains to be conducted.
Blake (1989) identifies two limitations in the previous work: lack of differentiation of various kinds of intellectual ability (such as verbal and nonverbal) and potential interactions with SES. She finds that the inverse relationship between sibship size and intelligence holds for measures of verbal skill, but not for measures of nonverbal ability, and that the verbal ability deficits observed among children in large families are not limited to those from more disadvantaged backgrounds.
Physical and Social-Psychological Development. Compared with other outcome measures, relatively little attention has been given to the study of sibship-size effects on children's physical and social-psychological development. Mednick and associates (1985) and Wagner and associates (1985) provide brief reviews of this literature. Family size has been found to be inversely related to children's height and weight; it is also positively correlated with morbidity and mortality. With regard to social-psychological development, children from larger families have been found to have poorer self-concepts, to value conformity and self-control rather than independence and self-expression, and to show a greater tendency toward anti-social behavior. They are also less likely to be interested in white-collar occupations.
Blake (1989) investigated the relationship between sibship size and educational expectations, using data from three different cohorts of youth, and found that young people from smaller families, as well as from higher-status families, tend to have higher educational goals. These effects, however, are mediated through ability and grades as well as through parents' expectations.
Educational Attainment. Blake's (1989) book Family Size and Achievement provides the most comprehensive assessment to date of this area. Two sets of questions are addressed: First, does sibship size affect educational expectations and attainment, and if so, where in the educational process? Second, what is the relative importance of sibship size, relative to other measures of family background?
With regard to the first question, sibship size does appear to have a substantial effect on educational attainment. Individuals from small families had approximately two additional years of schooling, relative to their peers from larger families—net of differences attributable to parental characteristics. The greatest impact on education occurred at the high school level, with individuals from larger families more likely to drop out of high school.
With regard to the second question, relative to other background variables in the analysis, sibship size was consistently second in importance for years of schooling, behind father's education. However, the negative effects of large families were somewhat mitigated by high parental SES and by membership in certain religious or ethnic groups. Similarly, the effects of parental SES were somewhat mitigated for youth in small families.
Some have argued that sibship size is simply a proxy for otherwise unmeasured characteristics of parents' family background and does not exert any independent effect on education in its own right. To address this concern, Blake (1989) examined the extent to which children from different-sized families have different home environments that might, in turn, influence educational attainment. In particular, attention was given to characteristics of the home setting (such as time spent reading newspapers, reading books, watching television) and to parental behaviors directed toward the child (such as encouragement, correction, goal setting). Children from smaller families were more likely to spend time in intellectual and cultural pursuits, to spend time playing alone, to have been read to as children, and to have had music or dance lessons. However, no significant differences were found in parental values for their children or in parenting style after parents' education and SES were taken into account. Thus, while there appear to be differences in the home environments afforded to children in smaller versus larger families, these differences do not appear to be attributable to differences in parental values or parenting style.
Socioeconomic Attainment and Mobility. A long tradition of research has addressed the question of how family background conditions or constrains individuals' socioeconomic attainment and social mobility. While primary consideration has been given to the impact of family social resources (father's education and occupation) on children's attainment, sibship size also was found to be related to occupational attainment (Blau and Duncan 1967). Among both women and men, those from larger families were more likely to have lower-status jobs and lower earnings, even after adjusting for differences in fathers' SES and educational attainment, both of which are correlated with family size. Among women, the effect of sibship size on earnings was stronger than the effect of father's occupation (Featherman and Hauser 1976). Using path analysis to model both indirect and direct relationships, however, Duncan and associates (1972) found that the negative effect of sibship size on men's occupational status could be accounted for primarily by the effect of sibship size on educational attainment. This finding lends some support to arguments that larger families result in a dilution of family economic resources, thus constraining the opportunities available to children.
Parents' Economic Well-Being. Duncan and associates (1972) examined the impact of family size (as contrasted with sibship size) as a contingency in men's socioeconomic attainment, finding a slight and negative effect on occupational status but a positive effect on earnings, net of other background variables. Studies that included women found evidence of reciprocal relationships between family size and labor-force participation, which in turn affected women's career attainment (Waite and Stolzenberg 1976). However, as noted previously, Bagozzi and Van Loo (1988) suggested that women's work and family size are not causally related but are mutually dependent on other, achievement-related characteristics of the wife.
Relationships have been reported between the timing of childbearing and subsequent economic well-being. Card and Wise (1978) found that teenage parents of both sexes tended to have less education, lower job prestige, and lower earnings, relative to later childbearers, net of differences in background characteristics. Investigating this relationship in greater depth, Hofferth and Moore (1979) found that the effects of early childbearing on women's subsequent earnings were primarily attributable to the larger family sizes of these women and to the consequent implications for (less) work experience. However, they also found that early childbearing was less of a handicap for black women, due to weaker relationships between early childbearing and subsequent education and employment. Hofferth (1984) found that among women aged 60 or over, the number of children per se was not related to measures of economic well-being, but that the timing of childbearing was: Those who delayed the first birth until after age thirty had higher family incomes and higher standards of living than did women whose first child was born before age thirty. This relationship was most pronounced among delayed childbearers who had small families, suggesting an interaction between timing of childbearing and family size.
Massagli (1987) has argued for a life-cycle model of the process of stratification that incorporates information on family size in both the parental and the filial generations. He hypothesizes that sibship size does not affect socioeconomic attainment directly but, rather, is related to the timing of early life-cycle transitions and to marital fertility; the observed negative effects of sibship size on attainment are attributed to the product of the relationship with life-cycle transitions and marital fertility and the negative effect of marital fertility on attainment.
Parental Attitudes and Well-Being. Wagner and associates (1985) review a number of studies of effects of family size on parental attitudes and parental health. They find that parental attitudes and treatment of children vary with family size: Larger families are more family centered, with a greater role played by fathers; at the same time, parents in larger families tend to be more authoritarian and more inclined to treat all children alike. Parents in larger families have also been found to have poorer marital relations. Finally, men and women who have many children are at greater risk of hypertension and other physical ailments.
In sum, sibship size and family size both appear to exert significant influence on the children and on the parents. Sibship size is closely related to family socioeconomic background, however, which is also a major influence on children's development and attainment. As a result, care must be taken to differentiate between effects of sibship size per se and effects of socioeconomic background. Similarly, family size among adults (the number of children they have) is highly correlated with socioeconomic status, intelligence, and other characteristics; again, it is important to consider the effects of family size net of these other factors. In many instances, the effects of sibship size and family size appear to be indirect. For example, sibship size is highly correlated with educational attainment and thus with subsequent occupational attainment. Similarly, among adults, family size is correlated with employment and thus with socioeconomic attainment. Finally, family size is often closely related to other characteristics of the family: Among children, it may be related to birth order, and among parents, it may be related to the timing of childbearing. Understanding these indirect as well as direct relationships yields a better understanding of the ways in which, and the extent to which, sibship size and family size may affect the lives of children and adults.
AT THE TURN OF THE CENTURY
The United States—as well as other developed and developing countries—has witnessed significant changes in fertility patterns and in family structure, which together combine to impact family size. This closing section reviews the more salient of these developments and examines how they have been reflected in recent sociological and demographic research.
Family Size and Fertility. Because family size is inextricably linked to fertility, it has been impacted by the fertility transition (i.e., the change from higher to lower rates of fertility) that has been well documented in the United States and is now being seen in both developed and developing societies elsewhere in the world. In the United States fertility has remained relatively constant since the early 1980s, ranging from 1.7 to 1.9 births per woman. However, this apparent stability masks a dramatic shift toward having children at later ages, especially among white women (Chen and Morgan 1991) and more highly educated women (Rindfuss et al. 1996).
The stability seen in the United States is in sharp contrast to Europe, where most countries have experienced significant declines in fertility during this period, and to many developing countries, which are also now evidencing fertility declines (Rutenberg and Diamond 1993; Thomas and Muvandi 1994). Global fertility projections for the twenty-first century (released by the United Nations in 1992) range from 1.7 to 2.5 births per woman (Cohen 1996). These declines have been linked to three factors:
- Widespread changes in the social and economic roles and opportunities available to women, including the increased availability of child care (Hirschman and Guest 1990; Mason and Kuhlthau 1992; Rindfuss et al. 1996)
- Increased availability of contraception and family-planning services, as well as in some developing countries policies supporting fertility limitation in some developing countries (Axinn 1992; DeGraff 1991; Lavely and Freedman 1990; Njogu 1991)
- Changes in the social norms governing childbearing and child rearing, including the emerging concept of "numeracy" about children—that is, the idea of having a particular family size as a goal—in developing countries (van de Walle 1992)
Corresponding decreases in actual and expected family size are also seen for this period. The average family size in 1993 was 3.16, down from 3.29 in 1980; similarly, the proportion of family households with three or more children had fallen by half since 1970 (Dortch 1993). On the 1994 General Social Survey 55 percent of Americans reported that they preferred two-child families—up from 41 percent in 1972—while the percentage of preferring substantially larger families declined commensurately. By 1988, the proportion of women expecting to remain childless had increased to 9 percent (National Center for Health Statistics 1996).
Family Size and Family Structure. Family size is also closely linked to family structure and to changes in patterns of family formation. Two somewhat related changes in particular have significantly impacted the size of family units: increased rates of marital dissolution and increased rates of outof-wedlock births, both of which have contributed to a dramatic increase in single-parent family units.
Rates of marital dissolution have increased dramatically, both in the United States and elsewhere. In the United States more than half of all marriages are now expected to end in divorce; in less developed countries, approximately 25 percent of first marriages, on average, have dissolved as a result of death, divorce, or separation (Bruce et al. 1995). Not only does marital dissolution contribute directly to smaller family size (Lillard and Waite 1993); it also has an indirect effect—maternal divorce not followed by remarriage substantially reduces children's preferred family size (Axinn and Thornton 1996).
Beginning in the 1980s, women were increasingly likely to have children out of wedlock, signaling a significant change in the norms governing childbearing. By the early 1990s, 2 out of 3 black children and nearly 1 of 4 white children were born to unmarried mothers (Smith et al. 1996). One-fourth of these out-of-wedlock births were to cohabiting couples (Bumpass 1990). Thus, while fewer women were marrying and staying married, alternative family structures involving children were emerging.
The number of single-parent families in the United States grew dramatically from 1960 (10.5 percent) to 1990 (23.3 percent) (Garasky and Meyer, 1996). As a result, it is estimated that half of today's young children will spend some time in single-parent family (Bumpass 1990). While the majority of single-parent family units are headed by the mother, the number of father-only families has grown at nearly twice the rate as the number of mother-only families. Nor is this phenomenon limited to the United States: In the former Soviet Union, the proportion of households headed by a single parent doubled in the fifteen-year period from 1980 to 1995 to 20 percent; in developing countries, the incidence of female-headed households as of 1995 ranged from 11 percent in the Philippines, to 13 percent in Mexico, to 19 percent in Cameroon, to more than 25 percent in Hong Kong (Bruce et al. 1995).
Implications for the Study of Family Size. Returning to the framework initially presented in this essay, what are the implications of these trends and developments for the conceptualization of the "family" and "family size," and for research on the correlates and implications of family size?
Conceptualization of the "family" and "family size." The decreasing variance in family size is being offset by increasing complexity in family structure. In addition to the growing interest in single-parent families—and within that category, differentiation of mother-only and father-only families—researchers also identify nonmarital cohabitation (Bumpass 1990), parent-stepparent and blended families (Astone and McLanahan 1991; Dortch 1993; Wojtkiewicz 1993), and intergenerational households (Macunovich and Easterlin 1990). This evolving conceptualization of the family and—in particular—family structure is of interest not only in its own right but also for its implications for models of intergenerational transmission of status, resources, and values (Smith et al. 1996).
Correlates of changes in family size and structure. Increasingly research is directed toward linking social change at a macro level to individual-level fertility behavior. Structural factors, including increased labor-force participation of women (Rindfuss et al 1996), availability of contraceptive technology (Lavely and Freedman 1990), and availability of child care (Mason and Kuhlthau 1992; Rindfuss et al. 1996), continue to be a subject of study in both developed and developing countries. Of equal interest is the social context surrounding childbearing decisions, including the husband's and wife's own values regarding desired family size (Thomson 1997; Thomson et al. 1990), their parents' preferences and behavior (Axinn et al. 1994; Axinn and Thornton 1996), and societal norms (van de Walle 1992). As increasing attention is given to fertility transitions occurring in other countries, attention is also being given to identifying cultural factors that can potentially bias data and findings, such as nonresponse or qualitative responses to questions about expected or desired family size (Hermalin and Liu 1990; Riley et al. 1993).
Implications of changes in family size and structure. Considerable attention continues to be devoted to studying the impact of family size and structure on children's achievement. The inverse relationship between family size and children's attainment that has been widely documented in the United States is also observed in a number of developing countries, including Thailand (Knodel and Wonsith 1991), Vietnam (Anh et al. 1998), Ghana (Lloyd and Gage-Brandon 1995), and Israel (Shavit and Pierce 1991). Research is increasingly focusing on delineating the processes underlying these relationships, including the greater availability of parental economic and interpersonal resources in smaller families (Downey 1995; Macunovich and Easterlin 1990; Powell and Steelman 1993). Similarly, studies of the negative impact of marital disruption on children's achievement also explore how social factors such as reductions in parental expectations and involvement mediate this relationship (Astone and McLanahan 1991; Wojtkiewicz 1993).
These changes in family size and structure have significant implications for policy as well as for research. Domestically, Dortch (1993) raises the question of how the trend toward smaller families will impact caring and support relationships for older family members, especially as the number of older American increases over the next few decades. In developing countries, where many governments are proactively working to foster economic development and social well-being, policies supporting lower fertility and smaller families may have both direct and indirect benefits: As the number of children coming from smaller families increases, so too should their prospects for educational and economic attainment (Knodel and Wonsith 1991).
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