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Identifying interaction effects using random fertility shocks
Abstract
BACKGROUND Fertility interaction effects in social networks increasingly attracts the interest of demographers. While these theories propose a causal mechanism, they are rarely put to test in a plausibly causal statistical design. OBJECTIVE We aim to differentiate network effects from selection by using an instrumental variable (IV) approach to achieve exogenous variation in fertility. We use interaction effects between siblings as an empirical example. METHODS We draw data from Norwegian administrative registers (N ~ 170,000 men and women). We use twin births and children's sex composition as random fertility shocks (IVs), generating exogenous variation in third births. RESULTS In our full study sample, we find no significant effects on ego's fertility of random shocks to the propensity to have three children. Subgroup analysis by sex and parity indicates positive effects for firstborn women when the sibling's birth is intended (as captured by the same-sex instrument). We find no evidence that similarity strengthens interaction effects. CONCLUSIONS The study contributes to the literature by testing long-standing hypotheses of fertility interaction effects in a plausibly causal design. With the exception of firstborn women, we find no evidence of interaction effects of a sibling's third birth.
... The two IVs employed in this paper represent quite different fertility experiences. The twin instrument captures the effect of a third child among couples who would otherwise have preferred only two children, whereas the sex-composition instrument captures the effect of a third birth among parents who would have stopped at two children if-and only if-they were of different sexes (see also Hart & Cools, 2019). For many reasons, having another child because of a desire for children of both sexes could be less demanding than having twins. ...
... For the twin instrument (column 1-3), we find multiple statistically significant differences by instrument status, some of them of sizeable magnitude. This finding is in line with previous applications, which show this instrument to be only conditionally random (Hart & Cools, 2019). ...
... To test whether twin births are conditionally random in this sample, in Table 3 we estimated how the IVs predict several other background characteristics, first without conditioning on the background variables in Table 2 (columns 1 and 3), then conditioning on them (columns 2 and 4). Under conditional independence, significant associations should disappear when background characteristics are controlled for in Table 2 (see also Hart & Cools, 2019). For the sex-composition instrument, there are no significant associations. ...
Numerous studies have shown that fertility behavior is spatially clustered. In addition to pure contextual effects, two causal mechanisms could drive this pattern. First, neighbors may influence each other's fertility and second, family size may influence decisions about where to live. In this study we examine these two potential causal mechanisms empirically, using the sex composition of the two eldest children and twin births as instrumental variables (IVs) for having a third child. We estimate how having a third child affects three separate outcomes: the fertility of neighbors; the propensity to move houses; and the likelihood of living in a family-friendly neighborhood with many children. We draw residential and childbearing histories (2000–2018) from Norwegian administrative registers (N ~ 167,000 women). Individuals' neighborhoods are defined using time-varying geocoordinates for place of residence. We identify selective moves as one plausible causal driver of residential clustering of large families. This study contributes to the understanding of fertility and relocation, and to the literature on the social interaction effects of fertility, by testing the relevance of yet another network: that of neighbors.
Supplementary Information
The online version contains supplementary material available at 10.1007/s10680-023-09655-6.
... This is a major limitation of this particular approach, although we argue that the prevailing statistical practices of focusing on the signs and significance of coefficients of a small set of variables based on a simple theoretic model chosen because of either cognitive or feasibility constraints cannot establish causality either. Sophisticated research designs using instrumental variables or quasi-experimental designs have been able to assess causal effects of social interactions on outcomes related to fertility [12,86,87]. Establishing causality in network studies is particularly difficult [88][89][90], because in addition to common background variables, people select individuals into their network [91], and are influenced by them. ...
People's networks are considered key in explaining fertility outcomes—whether people want and have children. Existing research on social influences on fertility is limited because data often come from small networks or highly selective samples, only few network variables are considered, and the strength of network effects is not properly assessed. We use data from a representative sample of Dutch women reporting on over 18 000 relationships. A data-driven approach including many network characteristics accounted for 0 to 40% of the out-of-sample variation in different outcomes related to fertility preferences. Individual characteristics were more important for all outcomes than network variables. Network composition was also important, particularly those people in the network desiring children or those choosing to be childfree. Structural network characteristics, which feature prominently in social influence theories and are based on the relations between people in the networks, hardly mattered. We discuss to what extent our results provide support for different mechanisms of social influence, and the advantages and disadvantages of our data-driven approach in comparison to traditional approaches.
... In another study, Hart and Cools (2019) attempted to identify sibling effects on fertility using twinning at second birth and having two children of the same sex as instruments. They argued that these two events are random shocks that can distinguish direct sibling effects from contextual and selection effects. ...
This study examined social interaction effects on family formation and dissolution, asking whether fertility, marital, and divorce behavior spread in the sibling network. Using panel data from the German SOEP (1984 – 2016; N = 4,521 individuals), we estimated discrete-time event history models with random effects at the individual to examine whether siblings’ transitions to parenthood, marriage, and divorce influence an individual’s chance to have children, marry, and divorce. Results show that the hazard of becoming a parent increased in the short term after a sibling had a child. Similarly, the hazard of getting married increased following a sibling’s marriage. Tentative evidence also suggested that transition rates to divorce increased in the longer term following a sibling’s divorce. Furthermore, we found evidence for social interaction effects across different transitions in the process of family formation, as the transition rates to marriage decreased after a sibling divorced. Conversely, the risk of divorce decreased following a sibling’s entry to marriage. Overall, these findings illustrate that the impact of network partners on demographic behavior is not limited to the same behavioral domain and might be negative as well as positive.
Parents with two boys or two girls are more likely to have a third child than those with a 'sex mix'. However, little is known on whether these 'mixed-sex preferences' extend beyond the nuclear family. This study leverages the random variation in sex at birth to assess whether the sex of nieces and nephews, in combination with own children, matters for fertility choices. Using three-generational data from the US Panel Study of Income Dynamics (PSID), I show that extended families (including grandparents, their children, and their grandchildren) are collectively more likely to have three or more grandchildren when lacking sex mix, whether the first two grandchildren are siblings or cousins. I explore the pathways for these offspring sex preferences, finding support for a preference for an uninterrupted line of male descendants. This multigenerational approach also contributes a new estimation strategy that causally estimates the effects of family sizes on outcomes beyond fertility.
Studies investigating how the number of children in a family affects the parents or the children face problems because the variable of interest is endogenous in the model. The currently accepted solution to this problem is to use instrumental variables (IVs), for example, based on twin births. In this paper, I review and add to the critique of IVs based on twin births and show that that there are so many issues—major and minor—with these IVs that results based on them are not reliable or interpretable. I also review other IVs used in the literature, for example IVs based on the sexes of the firstborn children, and conclude that there are, as of yet, no credible IVs for the number of children. We need to disregard results from studies applying these IVs, reevaluate the current state of knowledge, and develop new, more credible methods.
A vast body of research has emphasized the role of social networks and diffusion processes in the adoption of “new” demographic behavior, such as the reduction of fertility to below replacement levels, as part of the demographic transition. Diffusion theories integrate the role of individual behavior in explaining macro-level changes but, until very recently, empirical evidence at the micro level was scarce. Recent studies showed the existence of social contagion effects on fertility timing in contemporary population among siblings, friends and coworkers. Humans are social actors who make decisions and act while embedded in a web of social relationships with kin and peers, and sociologists and demographers have increasingly been acknowledging the role of interpersonal interactions in shaping fertility decision making. In this piece of work, we review the main mechanisms and processes through which fertility behavior may become contagious among relevant others, such as friends, kin, and coworkers. In doing so, we highlight the main sociological theories explaining the diffusion phenomenon at the micro-level, as well as the challenges deriving from the difficulty of disentangling “pure” social interaction effects from selection and contextual effects. The relevance of this identification problem is evident in the active and large debate on possible empirical strategies to disentangle confounding effects from diffusion. We also provide a useful overview of the existent data suitable to analyze peer effect on fertility, and discuss the potential use of big data.
Twin births are a well-known and widespread example of a so-called “natural experiment”. Instrumental variables based on twin births have been used in many studies to estimate the causal effect of the number of children on the parents or siblings. I use the potential outcomes framework to show that these instrumental variables do not work as intended. They are fundamentally flawed and will always lead to severely biased estimates without any meaningful interpretation. This has been overlooked in previous research because too little attention has been paid to defining the treatment in this natural experiment. I analyze three different possible interpretations of the treatment and show that they all lead to inherent violations of the necessary assumptions. The effect of the number of on the parents or siblings is a policy relevant and theoretically important issue. The scientific record should therefore be corrected to not lead to misguided decisions.
We estimate the effect of family size on various measures of labor market outcomes over the whole career until retirement, using instrumental variables estimation in data from Norwegian administrative registers. Parents’ number of children is instrumented with the sex mix of their first two children. We find that having additional children causes sizable reductions in labor supply for women, which fade as children mature and even turn positive for women without a college degree. Among women with a college degree, there is evidence of persistent and even increasing career penalties of family size. Having additional children reduces these women’s probability of being employed by higher-paying firms, their earnings rank within the employing firm, and their probability of being the top earner at the workplace. Some of the career effects persist long after labor supply is restored. We find no effect of family size on any of men’s labor market outcomes in either the short or long run.
Electronic supplementary material
The online version of this article (10.1007/s13524-017-0612-0) contains supplementary material, which is available to authorized users.
The focus of this report is on the impact of women’s economic activity, economic resources and education on first births and third births in the period 2000-2015. The main aim of the analyses is to investigate whether the impact of these factors has changed in the period, which saw a decrease in the total fertility rate (TFR) from 2010 compared to the preceding years.
The analyses are based on information from various administrative registers, which collectively cover the entire population of Norway. The sample consists of all women resident in Norway during the observed period. The analyses are divided into two parts: first births among women aged 20 to 39 years in the period 2000 to
2015, and third births of mothers with two children aged 20 to 49 years in the period from 2004 to 2015.
We apply event history models as the main method in the analyses, implying that a group of women is followed over time until the year of first or third birth. Based on discrete time hazard models, we quantify the impact of the different explanatory variables. The hazard is the conditional probability that an event, in our case a first
or third birth, will occur. For first births, we conclude that there are three factors that have a significant
impact on the decline of first births rates during the period with a falling TFR: (i) economic activity, (ii) work experience and (iii) unemployment in the municipality. All three factors are closely linked to the general economic situation in Norway and the labour market. The results therefore suggest that the probability of women in Norway having children is related to their economic situation as well as labour market conditions.
The decline in third births is a reflection of a long-lasting downward trend. Our results show that there are disparities between the groups in terms of the chance of having a third child, but most of these disparities are stable throughout the whole observation period. This means that the decline in third births is more of a general
trend across the different groups and that this trend has increased since 2010. This may be an indication that women now prefer to have fewer children than previously. Our results suggest that local unemployment rates have had a significant impact on the continued decline in third birth rates that has taken place since 2010. This factor is related to the general economic situation in Norway.
Background: Intergenerational transmission of fertility - a correlation between number of siblings and adult fertility - has been consistently demonstrated in developed countries. However, there is only limited knowledge of the causes of this correlation.
Objective: This study estimates the effect of an exogenous increase of number of siblings on adult fertility for men and women using Swedish register data. The effect of an additional sibling is estimated from the birth of younger twin siblings by means of instrumental variable methods.
Results: The study shows that there is no clear effect of an exogenous increase in the number of siblings on completed fertility. There is some evidence that an additional sibling is associated with lower fertility in adulthood.
Conclusions: The results indicate that intergenerational transmission of fertility is due to factors shared between parents and children such as preferences or socioeconomic status, not directly related to the size of the family of upbringing. There is no effect on fertility in adulthood of having an additional sibling per se.
URL: http://www.demographic-research.org/volumes/vol30/22/30-22.pdf
Background: The fields of demography, sociology, and socio-psychology have been increasingly drawing on social network theories, which posit that individual fertility decision-making depends in part on the fertility behavior of other members of the population, and on the structure of the interactions between individuals. After reviewing this literature, we highlight the benefits of taking a social network perspective on fertility and family research.
Objective: We review the literature that addresses the extent to which social mechanisms, such as social learning, social pressure, social contagion, and social support, influence childbearing decisions.
Methods: We review the most recent contributions of the social networks approach for the explanation of fertility dynamics in contemporary post-industrial societies.
Conclusions: We find that all of the social mechanisms reviewed influence the beliefs and norms individuals hold regarding childbearing, their perceptions of having children, and the context of opportunities and constraints in which childbearing choices are made. The actual impact of these mechanisms on fertility tempo and quantum strongly depends on the structure of social interaction.
Geographical variations in fertility have been observed within several countries in Northern Europe, with higher fertility in rural areas, smaller settlements and city suburbs. However, the processes underlying such fertility variations across residential contexts are not well understood. This paper contributes to the on-going debate by looking at local variations in fertility in Britain. It aims to disentangle the relative contribution of a number of factors, including the socio-economic characteristics of individuals, housing conditions, patterns of residential relocation and lastly, contextual factors stricto sensu. In addition, it seeks to identify those aspects of reproductive behaviour which are more likely to be associated with the observed spatial differences, and to distinguish between those that may be influenced by local context and those that respond to social influences at different scales. The focus is on local fertility contexts which, we argue, have the potential to influence the fertility behaviour of individuals through processes of social learning.
This paper investigates how social interactions among friends shape fertility. We specifically examine whether and how friends’ fertility behaviour affects an individual’s transition to parenthood. By integrating insights from economic and sociological theories, we elaborate on the mechanisms via which interactions among friends might affect an individual’s risk of becoming a parent. By exploiting the survey design of the Add Health data, we follow a strategy that allows us to properly identify interaction effects and distinguish them from selection and contextual effects. We engage in a series of discrete time event history models with random effect at the dyadic level. Results show that, net of confounding effects, a friend’s childbearing increases an individual’s risk of becoming a parent. We find a short-term, curvilinear effect: an individual’s risk of childbearing starts increasing after a friend’s childbearing, it reaches its peak around two years later, and then decreases.
Individuals' fertility decisions are most likely shaped not only by their own characteristics and life course paths, but also by social interaction with others through social networks. However, in practice it is often difficult to disentangle the role of social interaction from other factors like individual and family background variables. We propose to measure social interaction through the cross-sibling effects on fertility. Continuous-time hazard models are estimated separately for the women's first and second birth intensities. In addition to individual socioeconomic and demographic variables and a sibship-specific unobserved factor, siblings' birth events and their timing enter as time-varying covariates. We use data from longitudinal population- wide Norwegian administrative registers. The data set covers more than 110;000 sibships, and includes the siblings' fertility, education, income and marital histories. Our results indicate that cross-sibling effects are relatively strong for the respondent's first births, but weak for the second parity transi- tion. (148 words)
The article discusses the existence and outlook of an evolved desire to have children. Twin studies have found a genetic basis for conscious attempts to get pregnant. This heritable disposition increasingly affects societies of wide female reproductive choice (Kohler et al 1999). Based on 106 stories written by Finnish women in 2006, I analyse the symptoms, triggers and behaviour related to longing for babies. I suggest that a strong longing for first or subsequent children is an affective incentive of growing importance in low-fertility societies. Female desire for babies appears in two main forms: as part of a generally care-oriented personality and as a sudden, surprising and largely physical longing. The first type conforms to previous research on nurturing (Miller 1986; Foster 2000) while the second type has not been much studied yet. For both types, a desire to have children is often related to physical age, falling in love, previous pregnancies and to exposure to babies of kin and peers. I discuss evolutionary explanations and suggest that longing for babies may have evolved not only as a by-product of finding care pleasurable, but also as part of mate selection and as a consequence of hormonal changes induced by couple formation and ageing.
This paper uses Norwegian data to estimate the effect of family size on IQ scores of men. Instrumental variables (IV) estimates using sex composition as an instrument show no significant negative effect of family size; however, IV estimates using twins imply that family size has a negative effect on IQ scores. Our results suggest that the effect of family size depends on the type of family-size intervention and that there are no important negative effects of expected increases in family size. However, unexpected shocks to family size resulting from twin births have negative effects on the IQ scores of existing children.
The article investigates the different types of social mechanisms responsible for the interdependence of couples'' reproductive preferences predicted by diffusion models of fertility and family behavior. We analyze the transcripts of in-depth interviews carried out with 54 women in the northern part of Italy. The rich information on observations and conversations about fertility and family choices with relatives and peers enables us to distinguish four different ways in which social interaction influences reproductive preferences, namely social learning, social pressure, subjective obligation and contagion. Second, we show how the efficacy of each mechanism affecting fertility behavior depends on the kind and the structure of personal relationships involved in the interaction. Finally, we discuss the ways in which individual attitudes and values associated with the transition to parenthood are produced and negotiated in face-to-face interactions, and the importance of focusing on the process of preference-formationand modification for understanding fertility behavior.
Individuals' fertility decisions are shaped not only by their own characteristics and life course paths but also by social interaction with others. However, in practice, it is difficult to disentangle the role of social interaction from other factors, such as individual and family background variables. We measure social interaction through the cross-sibling influences on fertility. Continuous-time hazard models are estimated separately for women's first and second births. In addition to individual socioeconomic variables, demographic variables, and an unobserved factor specific to each sibling pair, siblings' birth events and their timing enter as time-varying covariates. We use data from longitudinal population-wide Norwegian administrative registers. The data cover more than 110,000 sibling pairs and include the siblings' fertility, education, income, and marital histories. Our results indicate that cross-sibling influences are relatively strong for the respondents' first births but weak for the second parity transition.
Below replacement fertility in many countries has lead to a renewed public interest in policies that may encourage young people to have more children. The Nordic countries are sometimes in focus in this respect, as their fertility rates remain relatively high in spite of very high female labour force participation. The key question is therefore whether there is a connection between generous public policies that facilitate childbearing and employment, and fertility. Using Norway as example and reviewing existing research evidence I conclude that generous family policies may be necessary, but not sufficient, to sustain fertility at a reasonable level. In particular, adverse macroeconomic conditions and rising unemployment have counteracting effects, as demonstrated by falling fertility rates in Sweden in the mid-1990s.
This study examines the differential availability of family and parenting resources to children depending on their birth planning status. The National Longitudinal Survey of Youth data were analyzed, 3,134 mothers and their 5,890 children (M = 7.1 years, range = 1 month-14.8 years), of whom 63% were intended at conception, 27% were mistimed, and 10% were unwanted. Fixed-effects models show that unwanted and mistimed children had fewer resources than intended siblings. Parents' emotional resources to older children decreased after the birth of a mistimed sibling. Findings suggest that cognitive and emotional resources are differentially available to children within a family depending on intention status and that unintended births lead to decreased parental resources for older children in the household.
There is an extensive theoretical literature that postulates a trade-off between child quantity and quality within a family. However, there is little causal evidence that speaks to this theory. Using a rich data set on the entire population of Norway over an extended period of time, we examine the effects of family size and birth order on the educational attainment of children. We find a negative correlation between family size and children's education, but when we include indicators for birth order or use twin births as an instrument, family size effects become negligible. In addition, higher birth order has a significant and large negative effect on children's education. We also study adult earnings, employment, and teenage childbearing and find strong evidence for birth order effects with these outcomes, particularly among women. These findings suggest the need to revisit economic models of fertility and child "production," focusing not only on differences across families but differences within families as well. © 2005 MIT Press
Research on the labor-supply consequences of childbearing is complicated by the endogeneity of fertility. This study uses parental preferences for a mixed sibling-sex composition to construct instrumental variables (IV) estimates of the effect of childbearing on labor supply. IV estimates for women are significant but smaller than ordinary least-squares estimates. The IV are also smaller for more educated women and show no impact of family size on husbands' labor supply. A comparison of estimates using sibling-sex composition and twins instruments implies that the impact of a third child disappears when the child reaches age thirteen. Copyright 1998 by American Economic Association.
Australia has moderately high fertility compared to many Western-industrialized countries. The current total fertility rate is around 1.88, but fertility levels are not uniform across the country. There is a distinct geographic pattern with the total fertility rate about 0.5 higher in remote and very remote Australia (2.33) compared to major cities (1.82). In this paper, we examine 2 explanations for this pattern: the compositional hypothesis and the contextual hypothesis. Using event-history methods with joint modelling to investigate parity progression, we find that after taking into account differences in age, country of birth, indigenous status, relationship status, education levels, and economic activity, women living in smaller towns in regional Australia are more likely to have a first, second, and third birth. Further, there is lower propensity to have a first child in inner or middle city areas that are characterized by smaller and more expensive housing than suburban or regional areas.
Although fertility is positively correlated across generations, the causal effect of children’s experience with larger sibships on their own fertility in adulthood is poorly understood. With the sex composition of the two firstborn children as an instrumental variable, we estimate the effect of sibship size on adult fertility using high-quality data from Norwegian administrative registers. Our study sample is all firstborns or second-borns during the 1960s in Norwegian families with at least two children (approximately 110,000 men and 104,000 women). An additional sibling has a positive effect on male fertility, mainly causing them to have three children themselves, but has a negative effect on female fertility at the same margin. Investigation into mediators reveals that mothers of girls shift relatively less time from market to family work when an additional child is born. We speculate that this scarcity in parents’ time makes girls aware of the strains of life in large families, leading them to limit their own number of children in adulthood.
Did mandatory busing programs in the 1970s increase the school achievement of disadvantaged minority youth? Does obtaining a college degree increase an individual's labor market earnings? Did the use of the butterfly ballot in some Florida counties in the 2000 presidential election cost Al Gore votes? If so, was the number of miscast votes sufficiently large to have altered the election outcome? At their core, these types of questions are simple cause-and-effect questions. Simple cause-and-effect questions are the motivation for much empirical work in the social sciences. This book presents a model and set of methods for causal effect estimation that social scientists can use to address causal questions such as these. The essential features of the counterfactual model of causality for observational data analysis are presented with examples from sociology, political science, and economics.
We estimate how parenthood affects hourly wages using panel data for Norwegian employees in the years 1997–2007. Though smaller than for most other OECD countries, we find substantial wage penalties to motherhood, ranging from a 1.2 % wage reduction for women with lower secondary education to 4.9 % for women with more than four years of higher education. Human capital measures such as work experience and paid parental leave do not explain the wage penalties, indicating that in the Norwegian institutional context, mothers are protected from adverse wage effects due to career breaks. We do however find large heterogeneity in the effects, with the largest penalties for mothers working full time and in the private sector. Contrary to most studies using US data and to previous research from Norway, we find a small wage penalty also to fatherhood. Also for men, the penalty is greater for those who work full time and in the private sector. A substantial share of the fatherhood wage penalty is explained by paternity leave.
This study builds on the peer effects in adolescent fertility literature by examining close friends and using miscarriages as a natural experiment to reduce potential confounding due to peer selection, simultaneity of peer influence, and shared environment. Our identifying assumption is that, conditional on a friend's pregnancy, the occurrence of a friend's miscarriage is an exogenous negative fertility shock that is uncorrelated with the unobservable factors. The study utilizes fertility and friendship nominations data from the core sample of Add Health. A total of 838 women had a friend with at least one teen pregnancy; of whom 647 had a friend who had a teen birth and 172 had a friend whose pregnancy ended in a miscarriage. A series of balancing and falsification tests support our identifying assumption of no correlation between the woman's characteristics and the occurrence of a friend's miscarriage in the pregnant friend subsample. The results suggest the existence of a sizable negative local treatment effect on teen childbearing among best friends. Multinomial logistic regression and IV results with controls for own and friend's fertility history, extensive set of socio-demographic controls, local peer network structure, and school-level fertility measures suggest that a friend's teen birth is associated with a 7-11 percentage point reduction in the likelihood of own teen childbearing. There is also evidence that this effect operates through a learning mechanism by changing attitudes toward early childbearing and reducing unwanted pregnancies.
Individual outcomes are highly correlated with group average outcomes, a fact often interpreted as a causal peer effect. Without covariates, however, outcome-on-outcome peer effects are vacuous, either unity or, if the average is defined as a leave-out mean, determined by a generic intraclass correlation coefficient. When pre-determined peer characteristics are introduced as covariates in a model linking individual outcomes with group averages, the question of whether peer effects or social spillovers exist is econometrically identical to that of whether a 2SLS estimator using group dummies to instrument individual characteristics differs from OLS estimates of the effect of these characteristics. The interpretation of results from models that rely solely on chance variation in peer groups is therefore complicated by bias from weak instruments. With systematic variation in group composition, the weak IV issue falls away, but the resulting 2SLS estimates can be expected to exceed the corresponding OLS estimates as a result of measurement error and for other reasons unrelated to social effects. Research designs that manipulate peer characteristics in a manner unrelated to individual characteristics provide the most compelling evidence on the nature of social spillovers. As an empirical matter, designs of this sort have mostly uncovered little in the way of socially significant causal effects.
This article investigates the causal relationship between the number of biological children and mental health of elderly Europeans. Specifically, we ask whether additional children improve or threaten parents' mental health status. The identification of causal effects draws on two natural experiments that exogenously increase the number of children: multiple births and the sex composition of the first two children. This setup allows us to identify the effect of expected and desired as well as the effect of unexpected additional children on mental health. For women, we find conflicting evidence regarding the effect of additional children on mental health, and we only find a negative effect of having additional children on mental health using multiple birth at the second pregnancy as instrument. Thus, it takes a rare and somewhat particular situation to uncover the negative effect. There is no evidence for a causal effect of additional children on the probability to suffer from depression for elder men.
Using panel data (N=1.679 married and cohabiting couples), this paper investigates the presence and causal mechanisms of social contagion processes regarding first births. Results confirmed the hypothesized positive association between the number of network members (friends, acquaintances, siblings) with young children and the respondents' transition rate into parenthood, particularly among younger couples. Several potential intervening mechanisms underlying this social contagion effect were tested. First, evidence was found for observational learning processes in which Ego obtained information on the joys and challenges of parenthood from network members with children. Second, childless respondents tended to feel pressured from couples with children in the network to start a family. Third, results supported the notion of social opportunity costs in that the anticipated loss of social ties after becoming a parent was more likely the fewer parents there were in the network. All three mechanisms exerted a positive impact on both fertility intentions and behavior. Panel regression models relying on intraindividual change scores showed that social learning was the most robust mechanism. An additional indirect test for causality suggested that the findings were unlikely to merely reflect parental status homophily (i.e., selection effects).
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We estimate peer effects in paid paternity leave in Norway using a regression discontinuity design. Coworkers and brothers are 11 and 15 percentage points, respectively, more likely to take paternity leave if their peer was exogenously induced to take up leave. The most likely mechanism is information transmission, including increased knowledge of how an employer will react. The estimated peer effect snowballs over time, as the first peer interacts with a second peer, the second peer with a third, and so on. This leads to long-run participation rates which are substantially higher than would otherwise be expected.
Using multiple births as source of variation, we study the impact of fertility on the overall wellbeing of mothers. First, using US Census data for the year 1980, we study the impact of number of children on family arrangements, welfare participation and poverty status. Second, using the National Health Interview Survey (NHIS) for the period 1982-2003, we study the impact on a series of health risk factors. The findings reveal, first, that an increase in family size increases the likelihood of marital breakdown. Second, we find evidence that mothers facing an increase in family size are not only more likely to live with other family members such as grandparents, aunts and uncles, they are also more likely to receive help from welfare programs. Third, consistent with an increase in welfare participation, families (mothers) are more likely to fall below the poverty line, and they face a reduction in total family income. The results using NHIS confirm a negative impact of fertility on marriage stability and an increase in welfare participation measured by the likelihood of using Medicaid and for some samples a reduction in the take-up of private health insurance. Finally, we find evidence that a shock in fertility increases the likelihood of mothers suffering from high blood pressure and becoming obese.
There is relatively little research on peer effects in teenage motherhood despite the fact that peer effects, and in particular social interaction within the family, are likely to be important. We estimate the impact of an elder sister’s teenage fertility on the teenage childbearing of their younger sister. To identify the peer effect we utilize an educational reform that impacted on the elder sister’s teenage fertility. Our main result is that within families, teen births tend to be contagious and the effect is larger where siblings are close in age and for women from low resource households.
Individual-level retrospective data from the Family and Occupation Survey of 1988 are used to estimate the effects of various employment variables on the third-birth rates among post-war Norwegian birth cohorts. Women who appear to have a strong work orientation, and may face relatively high opportunity costs of childbearing, do not have particularly low probability of advancing to parity three. This is consistent with previous Swedish and British studies, and lends some support to the view that other factors than stronger employment preferences and increased job opportunities have been largely responsible for the second demographic transition in Europe.On utilise ici des donnes rtrospectives individuelles, issues de l'enqute sur la Famille et la Profession de 1988, pour estimer les effets de diverses variables concernant l'emploi sur les taux de fcondit de rang trois de cohortes norvgiennes nes aprs la guerre. Les femmes qui semblent avoir une forte orientation vers la vie active, et qui peuvent faire face des cots relativement levs pour leurs enfants, n'ont pas une probabilit particulirement basse d'avoir un troisime enfant. Ce rsultat est en accord avec des tudes sudoises et anglaises antrieures, et donne quelque appui la thse selon laquelle d'autres facteurs qu'un attrait plus fort vers la vie active et des offres d'emploi croissantes, ont t la cause principale de la seconde transition dmographique en Europe.
Although estimates of the fertility-labor supply relationship abound, a full appreciation of the interpretation of such estimates has been lacking, regardless of the empirical strategy employed. This paper attempts to elucidate, within the context of a life-cycle decision-making process, the information contained in the estimated association between fertility and labor supply as calculated from "single" and "simultaneous-equations" estimation techniques. We also present a statistical methodology based upon the occurrence of twins in the first pregnancy and provide estimates, using that methodology, of the extent to which women's life-cycle labor supply decisions respond to exogenous (and, in this case, unanticipated) extra children.
There is subnormal dispersion in the distributions of the combinations of the sexes in some samples of litters of pigs, rabbits and mice. For instance, consider litters of exactly size 8. As contrasted with binomial expectation, there are too many with exactly 4 males and 4 females, and too few unisexual litters. It is argued that this supports the hypothesis (independently proposed by the author and by Guerrero) that P, the probability that a zygote will be male, varies with the time at which it is formed within the cycle. It is noted that data of Kaufman seem to support the hypothesis.
An analysis of the educational attainment of more than 10,000 members of the 1966 cohort of births in Northern Finland found that 25% of the young men born following an unwanted pregnancy failed to attain any more education than the nine years of compulsory schooling, compared with 18% of those born as a result of a mistimed pregnancy and 14% from a wanted one. The comparable proportions for women in the cohort were 19%, 13% and 9%, respectively. A binary regression analysis that controlled for family background variables indicates that unwantedness increased the risk that men would not go on to upper secondary school by 6.0 percentage points and that women would not by 6.3 percentage points. The statistical interaction between large family size and unwantedness showed an increased risk of low educational attainment among the young men; neither large family size nor other family background variables could explain the association between unwantedness at birth and comparatively little schooling among the women.
A long-held belief among mental health practitioners is that being born unwanted carries a risk of negative psychosocial development and poor mental health in adulthood. The Prague Study was designed to test this hypothesis. It followed the development and mental well-being of 220 children (now adults) born in 1961-63 in Prague to women twice denied abortion for the same unwanted pregnancy. The children were individually pair-matched at about age nine with 220 children born from accepted pregnancies when no abortion had been requested. This article brings together in one place the theoretical assumptions and hypotheses, the criteria for selecting the study participants and major findings from five follow-up waves conducted among the children around the ages of 9, 14-16, 21-23, 28-31 and 32-35 years, plus a sub-study of married unwanted pregnancy subjects and accepted pregnancy controls at ages 26-28. To control for potential confounding factors in data interpretation, all siblings of all subjects were included in the last two waves. It was found that differences in psychosocial development widened over time but lessened at around age 30. All the differences consistently disfavoured the unwanted pregnancy subjects, especially only children (no siblings). They became psychiatric patients (especially in-patients) more frequently than the accepted pregnancy controls and also more often than their siblings. The overall findings suggest that, in the aggregate, denial of abortion for unwanted pregnancy entails an increased risk for negative psychosocial development and mental well-being in adulthood.
The predictive content of the quantity-quality model of fertility and the empirical information required for verification under a minimal set of restrictions on the utility function is described. It is demonstrated that commodity-independent compensated price effects must be known to infer the existence of the unobservable interdependent shadow prices of the model with a relatively weak structure improsed on preference orderings. A method of using multiple birth events to substitute for these exogenous prices is proposed and applied to household data from India.
Spatial variations in family size and the neighbor's role for transition to third birth
- J Bergsvik
- T Lappegård
- T Skardhamar
Bergsvik, J., Lappegård, T., and Skardhamar, T. (2016). Spatial variations in family size
and the neighbor's role for transition to third birth. Paper presented at the Annual
Meeting of the Population Association America, Washington, D.C., USA, March 31-April 2, 2016.
The effect of sibship size on fertility in adulthood: New evidence from IV estimation
- S Cools
- R Hart
Cools, S. and Hart, R. (2017). The effect of sibship size on fertility in adulthood: New
evidence from IV estimation. Demography 53(1): 23-44. doi:10.1007/s13524-0160537-z.
Children and careers: How family size affects parents' labor market outcomes in the long run
- S Cools
- S Markussen
- M Strøm
Cools, S., Markussen, S., and Strøm, M. (2017). Children and careers: How family size
affects parents' labor market outcomes in the long run. Demography 54(5): 17731793. doi:10.1007/s13524-017-0612-0.
Parenthood wage penalties in a double income society
- S Cools
- M Strøm
Cools, S. and Strøm, M. (2017). Parenthood wage penalties in a double income society.
Review of Economics of the Household 14(2): 391-416. doi:10.1007/s11150-0149244-y.
Mellom arbeidsliv og familieliv: Hvilken betydning har arbeidsmarkedssituasjonen for om menn og kvinner velger a˚ fa˚ barn? [Between family life and work life: how does the labor market matter for childbearing decisions?
- Cools
Cools, S. and Strøm, M. (2018). Mellom arbeidsliv og familieliv: Hvilken betydning har
arbeidsmarkedssituasjonen for om menn og kvinner velgerå få barn? [Between family
life and work life: how does the labor market matter for childbearing decisions?]. Oslo:
Institute for Social Research (Rapport 2018:13).
Geographical variations in fertility and transition to second and third birth in Britain
- F Fiori
- E Graham
- Z Feng
Fiori, F., Graham, E., and Feng, Z. (2014). Geographical variations in fertility and transition to second and third birth in Britain. Advances in Life Course Research 21: 149167. doi:10.1016/j.alcr.2013.11.004.
Intergenerational transmission of fertility intentions and behaviour in Germany: The role of contagion
- M Kotte
- V Ludwig
Kotte, M. and Ludwig, V. (2011). Intergenerational transmission of fertility intentions
and behaviour in Germany: The role of contagion. Vienna Yearbook of Population
Research 9: 207-226. doi:10.1553/populationyearbook2011s207.
Is having babies contagious? Estimating fertility peer effects between siblings
- Kuziemko
Kuziemko, I. (2006). Is having babies contagious? Estimating fertility peer effects between siblings. Princeton: Princeton University (Technical report).