Generative
Olga Yakusheva & Jason Fletcher
Review of Economics and Statistics, forthcoming
Abstract:
We examine peer effects in teen childbearing among close friends, using miscarriages as a natural experiment. We use 775 women from the core sample of Add Health who had a friend with a teen pregnancy. We find a sizable negative treatment effect – a close friend's teen birth is associated with a 6 percentage point reduction in the likelihood of own teen pregnancy and childbearing. There is evidence that this effect operates through a learning mechanism by changing beliefs regarding early childbearing. Effects of teen pregnancy prevention policies may be partially offset by reductions in the opportunities for social learning.
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The Consequences of Teenage Childbearing Before Roe v. Wade
Kevin Lang & Russell Weinstein
NBER Working Paper, November 2013
Abstract:
Using data from three cycles of the National Survey of Family Growth, we investigate whether there were adverse consequences of teenage childbearing in the 1950s and 1960s, when most abortions were illegal, and access to the pill was limited. We find negative effects of teen motherhood on the likelihood of obtaining at least 12 years of education and on the number of marriages. We find positive effects of teen motherhood on family income, and, unsurprisingly, on the number of children. These effects are heterogeneous by predicted education. For those with high levels of predicted education, giving birth does not affect educational attainment but increases the probability of being divorced. For those predicted to be on the margin of high school completion, giving birth has strong negative effects on 12th grade completion and age at first marriage, while increasing the probability of never having married. In general, for less advantaged teens, motherhood appears to have increased expected family income but also the risk of not graduating from high school and never marrying. We find surprisingly little evidence that births affected teens conceiving pre- and post-marriage differently.
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Sara Vasilenko, Derek Kreager & Eva Lefkowitz
Journal of Research on Adolescence, forthcoming
Abstract:
Although sexual risk behavior occurs in a dyadic context, most studies of adolescent sexual behavior focus on individuals. This study uses couple data (N = 488 couples) from the National Longitudinal Study of Adolescent Health to examine how partners' contraceptive attitudes correlate over time and whether male or female partners' attitudes are better predictors of condom use. Net of their own prior attitudes, partners' prior attitudes predicted both male and female adolescents' Wave 2 attitudes. This association was stronger for female than for male adolescents, suggesting that female attitudes were influenced more by males' prior attitudes than vice versa. When entered together, only male adolescents' attitudes predicted dyadic condom use. Findings suggest that male partners may have greater influence on adolescent contraceptive decisions and that prevention programs should emphasize the relational context of sexual behavior.
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What a Difference a Day Makes: Quantifying the Effects of Birth Timing Manipulation on Infant Health
Lisa Schulkind & Teny Maghakian Shapiro
Journal of Health Economics, January 2014, Pages 139–158
Abstract:
Scheduling births for non-medical reasons has become an increasingly common practice in the United States and around the world. We exploit a natural experiment created by child tax benefits, which rewards births that occur just before the new year, to better understand the full costs of elective c-sections and inductions. Using data on all births in the U.S. from 1990 to 2000, we first confirm that expectant parents respond to the financial incentives by electing to give birth in December rather than January. We find that most of the manipulation comes from changes in the timing of c-sections. Small birth timing changes, even at full-term, lead to lower birthweight, a lower Apgar score, and an increase in the likelihood of being low birthweight.
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Jeff Dennis & Stefanie Mollborn
Social Science Journal, December 2013, Pages 625–634
Abstract:
This study considers how low birth weight (LBW) prevalence varies by race/ethnicity and maternal age and explores mechanisms that explain disparities. Results show that maternal age patterns in LBW risk for African Americans differ from Whites and foreign- and U.S.-born Hispanics. Background socioeconomic disadvantage, together with current socioeconomic status and smoking during pregnancy, explain almost all of the LBW disparity between white teenage mothers and their older counterparts. These findings suggest that social disadvantage is a primary driver in unfavorable birth outcomes among white teenage mothers compared to older white mothers. Alternatively, background disadvantage and other social characteristics explain very little of the LBW disparities among African Americans and U.S.- and foreign-born Hispanics. Overall, these results indicate LBW disparities by maternal age are a complex product of socioeconomic disadvantage and current social and behavioral factors, such that LBW risk does not operate uniformly by race/ethnicity or maternal age.
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Be Fruitful and Multiply? Moderate Fecundity and Long-Run Reproductive Success
Oded Galor & Marc Klemp
Brown University Working Paper, December 2013
Abstract:
This research presents the first evidence that moderate fecundity maximized long-run reproductive success within the human species. Exploiting an extensive genealogy record for nearly half a million individuals in Quebec during the seventeenth and eighteenth centuries, the study traces the number of descendants of early inhabitants in the subsequent four generations. Using the time interval between the date of marriage and the first live birth as a measure of reproductive capacity, the research establishes that while a higher fecundity is associated with a larger number of children, an intermediate level maximizes long-run reproductive success. The finding further indicates that the optimal level of fecundity was below the population median, suggesting that the forces of natural selection favored individuals with a lower level of fecundity. The research lends credence to the hypothesis that during the Malthusian epoch, natural selection favored individuals with a larger predisposition towards child quality, contributing to the onset of the demographic transition and the evolution of societies from an epoch of stagnation to sustained economic growth.
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Ilona Nenko, Adam Hayward & Virpi Lummaa
Proceedings of the Royal Society: Biological Sciences, 22 January 2014
Abstract:
Individual variation in nutritional status has direct implications for fitness and thus is crucial in shaping patterns of life-history variation. Nevertheless, it is difficult to measure in natural populations, especially in humans. Here, we used longitudinal data on individual life-histories and annual crop yield variation collected from pre-industrial Finnish populations experiencing natural mortality and fertility to test the validity of first birth interval (FBI; time between marriage and first birth) as a surrogate measure of nutritional status. We evaluated whether women with different socio-economic groups differ in length of FBI, whether women of poorer socio-economic status and experiencing lower crop yields conceive slower following marriage, and whether shorter FBI is associated with higher lifetime breeding success. We found that poorer women had longer FBI and reduced probability of giving birth in months with low food availability, while the FBI of richer women was not affected by variation in food availability. Women with shorter FBI achieved higher lifetime breeding success and a faster reproductive rate. This is, to our knowledge, the first study to show a direct relationship between environmental conditions and speed of childbirth following marriage, highlighting the value of FBI as an indicator of nutritional status when direct data are lacking.
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The Apparent Failure of Russia's Pronatalist Family Policies
Tomas Frejka & Sergei Zakharov
Population and Development Review, December 2013, Pages 635–647
Abstract:
Russia has a history of pronatalist policies dating back to the 1930s. Two sets of pronatalist measures were implemented during the past 40 years. The one designed in the early 1980s proved to be a clear failure. Instead of raising fertility, completed cohort fertility declined from 1.8 births per woman for the 1960 birth cohort to 1.6 for the 1968 cohort. The government of President Putin became concerned with the dire demographic conditions of high mortality and low fertility in Russia in the 1990s and early 2000s. A comprehensive set of pronatalist measures came into effect in January 2007. The period total fertility rate increased from 1.3 births per woman in 2006 to 1.6 in 2011, which the authorities view as an unqualified success. An unbiased demographic evaluation as well as analyses of Russian experts reveals that apparently the measures mainly caused a lowering of the age at birth and shortening of birth intervals. It appears that any real fertility increase is questionable, i.e. cohort fertility is not likely to increase appreciably. The recent pronatalist measures are likely to turn out to be a failure.
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Vikesh Amin & Jere Behrman
Journal of Population Economics, January 2014, Pages 1-31
Abstract:
Using data on monozygotic (MZ) (identical) female twins from the Minnesota Twin Registry, we estimate the causal effect of schooling on completed fertility, probability of being childless, and age at first birth using the within-MZ twins methodology. We find strong cross-sectional associations between schooling and the fertility outcomes, and some evidence that more schooling causes women to have fewer children and delay childbearing, though not to the extent that interpreting cross-sectional associations as causal would imply. Our conclusions are robust when taking account of (1) endogenous within-twin pair schooling differences due to reverse causality and (2) measurement error in schooling. We also investigate possible mechanisms and find that the effect of women’s schooling on completed fertility is not mediated through husband’s schooling but may be mediated in part through age at first marriage.
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Fertility and Social Interaction at the Workplace: Does Childbearing Spread Among Colleagues?
Thomas Leopold, Henriette Engelhardt & Sebastian Pink
Advances in Life Course Research, forthcoming
Abstract:
This research investigates whether colleagues’ fertility influences women's transitions to parenthood. We draw on Linked-Employer-Employee data (1993 - 2007) from the German Institute for Employment Research comprising 33,119 female co-workers in 6,579 firms. Results from discrete-time hazard models reveal social interaction effects on fertility among women employed in the same firm. In the year after a colleague gave birth, transition rates to first pregnancy double. This effect declines over time and vanishes after two years. Further analyses suggest that the influence of colleagues’ fertility is mediated by social learning.
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E.J. Steele et al.
Human Reproduction, January 2014, Pages 155-160
Study question: Does time in casual employment (while not studying full time) affect the likelihood of a woman having a child by age 35?
Study design, size, duration: A retrospective cross-sectional component (n = 663) was added to an existing study based on a cohort of women born during 1973–1975. An event history calendar instrument was used to obtain data regarding a range of life domains over a 20-year period.
Participants/materials, setting, methods: Using data from the Life Journeys of Young Women Project carried out in Adelaide, South Australia, Cox proportional hazards models were applied to investigate the research questions.
Main results and the role of chance: The likelihood of childbirth by around age 35 was reduced for every year spent in casual employment, irrespective of socioeconomic status, partner's education and parents' birthplace. The likelihood was reduced by 8, 23 and 35% for 1, 3 and 5 years spent in casual employment, respectively.
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Lauren Ralph et al.
Journal of Adolescent Health, forthcoming
Purpose: Despite the prevalence of laws requiring parental involvement in minors' abortion, little is known about the effect of parental involvement on minors' abortion decision making and anticipated coping after abortion.
Methods: We analyzed data from medical charts and counseling needs assessment forms for 5,109 women accessing abortion services at a clinic in 2008, 9% (n = 476) of whom were minors aged 17 years and under. We examined differences in abortion characteristics, including parental and partner involvement, between minors and adults, and used multivariate logistic regression models to examine predictors of parental involvement and support, confidence in the decision, and anticipated poor coping among minors.
Results: Most minors reported that their mothers (64%) and partners (83%) were aware of their abortion. Younger age was associated with increased odds of maternal awareness and reduced odds of partner awareness. Compared with adults, minors were more likely to report external pressure to seek abortion (10% vs. 3%), and mothers were the most common source of pressure. Minors overall had high confidence in their decision and anticipated feeling a range of emotions post-abortion; minors who felt pressure to seek abortion were less likely to report having confidence in their decision (odds ratio = .1) and more likely to report anticipating poor coping (odds ratio = 5.6).
Conclusions: Most minors involve parents and partners in their decision making regarding abortion, and find support from these individuals. For a minority, experiencing pressure or lack of support reduces confidence in their decision and increases their likelihood of anticipating poor coping after an abortion.
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Sebastian Klüsener, Karel Neels & Michaela Kreyenfeld
Population and Development Review, December 2013, Pages 587–610
Abstract:
Countries in Northwestern Europe, including Belgium, report cohort fertility levels of close to two children per woman; whereas Central European countries, such as Germany, have levels of around 1.6 children. In seeking to explain these differences, some scholars have stressed the role of the social policy context, while others have pointed to variation in fertility-related social norms. But because these influences are interdependent, it is difficult to isolate their effects on fertility trends. This study attempts to disentangle these two factors by drawing on a quasi-natural experiment. After World War I Germany was compelled to cede the Eupen–Malmedy territory to Belgium. The population of this region has retained its German linguistic identity, but has been subject to Belgian social policies. We examine whether the fertility trends in this German-speaking region of Belgium follow the Belgian or the German pattern. Our findings indicate that they generally resemble the Belgian pattern. This suggests that institutional factors are important for understanding the current fertility differences in Western Europe.
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Ashley Barr et al.
Journal of Youth and Adolescence, December 2013, Pages 1884-1897
Abstract:
Despite the declining rate of teen pregnancies in the United States, academic and public health experts have expressed concern over the still relatively high rate of rapid repeat pregnancies among adolescents, particularly among minority youth. Using a sample of over 300 African American female adolescents, the current study used insights from the prototype/willingness model of adolescent risk behavior to explore this risk. More specifically, it assessed the relationship between entry into unwed motherhood during mid-to-late adolescence and changes in prototypes of unmarried pregnant teens. Further, it explored the extent to which these changing prototypes accounted for young mothers’ later contraceptive expectations. We tested the possibility that social images were affected not only by personal experience (the birth of a child) but also by the family and community context in which this experience took place. The findings show that the early entrance into teen motherhood was associated with a shift toward more favorable prototypes of unwed pregnant teens, but that this was only the case for young mothers in disadvantaged contexts. Given this, prototype changes helped to explain the link between teen motherhood and contraceptive expectations only for those in disadvantaged contexts. We discuss these findings in terms of their practical and theoretical implications.
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Male microchimerism and survival among women
Mads Kamper-Jørgensen et al.
International Journal of Epidemiology, forthcoming
Background: During pregnancy, woman and fetus exchange small quantities of cells, and their persistence at later times is termed microchimerism. Microchimerism is known to substantially impact on women’s later health. This study examined the survival of women according to male microchimerism status.
Methods: Male microchimerism presence, measured as Y chromosome in peripheral blood samples, was determined in 272 women from the large Danish Diet, Cancer and Health cohort when aged 50–64 years during 1993–97. Women were followed up for cause-specific death in national Danish registers until the end of 2009. Survival was analysed using Cox regression.
Results: A total of 190 women (70%) were male microchimerism positive. During follow-up 21 women died, of whom 11 (52%) were male microchimerism positive at enrolment and 10 were negative. Of the 21 deaths, 13 (62%) were due to cancer and 5 (24%) were due to cardiovascular disease. Male microchimerism presence was associated with a reduced hazard ratio of all-cause mortality of 0.42 (95% CI 0.17–1.03). The hazard ratio of death from cancer and cardiovascular disease was 0.24 (95% CI 0.08–0.79) and 1.66 (95% CI 0.18–15.48), respectively, among male microchimerism positive compared with negative women.
Conclusions: Although the biological mechanisms are not precisely known, male microchimerism presence in peripheral blood of women is associated with substantially improved survival in women. The results also indicate that the association with male microchimerism may vary between different causes of death.
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Fertility Treatments and Multiple Births in the United States
Aniket Kulkarni et al.
New England Journal of Medicine, 5 December 2013, Pages 2218-2225
Background: The advent of fertility treatments has led to an increase in the rate of multiple births in the United States. However, the trends in and magnitude of the contribution of fertility treatments to the increase are uncertain.
Methods: We derived the rates of multiple births after natural conception from data on distributions of all births from 1962 through 1966 (before fertility treatments were available). Publicly available data on births from 1971 through 2011 were used to determine national multiple birth rates, and data on in vitro fertilization (IVF) from 1997 through 2011 were used to estimate the annual proportion of multiple births that were attributable to IVF and to non-IVF fertility treatments, after adjustment for maternal age. Trends in multiple births were examined starting from 1998, the year when clinical practice guidelines for IVF were developed with an aim toward reducing the incidence of multiple births.
Results: We estimated that by 2011, a total of 36% of twin births and 77% of triplet and higher-order births resulted from conception assisted by fertility treatments. The observed incidence of twin births increased by a factor of 1.9 from 1971 to 2009. The incidence of triplet and higher-order births increased by a factor of 6.7 from 1971 to 1998 and decreased by 29% from 1998 to 2011. This decrease coincided with a 70% reduction in the transfer of three or more embryos during IVF (P<0.001) and a 33% decrease in the proportion of triplet and higher-order births attributable to IVF (P<0.001).
Conclusions: Over the past four decades, the increased use of fertility treatments in the United States has been associated with a substantial rise in the rate of multiple births. The rate of triplet and higher-order births has declined over the past decade in the context of a reduction in the transfer of three or more embryos during IVF.