Hanbo Wu

Publications

Wu, Hanbo, and Luca Maria Pesando. 2026. “No Evidence that Anti-Domestic Violence Laws Reduce Violent Child Discipline in sub-Saharan Africa.” Social Science & Medicine 401:119335.

Albeit rarely recognized as such in existing legislation, violent child discipline is a clear form of domestic violence (DV) with enduring consequences for child well-being. This study merges household survey data from 27 sub-Saharan African countries with World Bank data on law implementation to investigate whether broad DV legislation introduced since the mid-2000s has curbed violent parenting practices. Using a quasi-experimental approach to compare childrearing practices and attitudes between countries with and without anti-DV laws, before and after law implementation, we document a robust increase in violent child discipline—mainly driven by emotional punishment—and a higher endorsement of harsh parenting practices following the introduction of these laws. These adverse effects are attenuated in countries with higher income inequality, where the laws appear to play more of a “protective” role. Our findings underscore the unintended consequences when anti-DV legislation is enacted without a specific target for child protection.

Wu, Hanbo. 2025. “Does Exposure to Armed Conflict Affect Women’s Attitudes Toward Intimate Partner Violence? Evidence from Vietnam.” Journal of Population Economics 38(4):78.

This study combines individual-level survey data and province-level data on wartime bombing to assess the long-term impact of the Vietnam War on Vietnamese women’s attitudes toward intimate partner violence (IPV). To establish a causal link, I use a province’s distance to the arbitrarily drawn border between North Vietnam and South Vietnam as an instrument for bombing intensity in that province. I find that women living in heavily bombed provinces are more likely to accept IPV. The instrumental variable estimates are greater in magnitude than the ordinary least squares estimates across various specifications. Exposure to bombing does not seem to make women more tolerant of IPV through education or marital matching. Instead, some suggestive evidence indicates that the normalization of and desensitization to violence in the domestic sphere as well as war trauma likely play an important role in explaining the effect of conflict exposure on the justification of IPV.

Wu, Hanbo, and Luca Maria Pesando. 2025. “Demographic Convergence in Marriage Timing: Intersecting Gender and Educational Expansion.” Demographic Research 52(14):415–444.

Background: Considering the massive educational expansion and dramatic changes in marriage timing the world is undergoing, this study explores whether the timing of marriage has become increasingly similar across countries amid educational expansion at different levels.Objective: First, we focus on convergence in marital timing, a core family demography indicator often overlooked in the convergence literature. Second, we shift the focus from demographic convergence over time to convergence over educational expansion. Third, we incorporate a gender perspective into the analysis, taking into consideration gender differences in educational expansion and union formation.Methods: We combine time-series data from 1950 to 2015 covering 144 countries from two data sources: (1) sex-specific singulate mean age at marriage (SMAM) from World Marriage Data; (2) sex-specific educational attainment by age from Barro and Lee. Methodologically, we explore whether convergence in marriage indicators has occurred over educational attainment by testing for β-convergence.Results: Age at marriage has strongly converged over measures of educational attainment, with far stronger convergence among women. We uncover two types of educational gradients: (1) convergence is stronger the higher the level of education (tertiary > secondary > primary); (2) within each level, completion of education contributes more to convergence in SMAM relative to just attendance.Conclusions: The study is unique in showing that convergence in SMAM masks fundamental heterogeneity, pointing to the growing importance of secondary and tertiary education worldwide. Relatedly, results call for a shift in policy focus from school attendance to successful school cycle completion.Contribution: Findings provide important insights for addressing key challenges in global development and demography.

Wu, Hanbo, and Luca Maria Pesando. 2024. “Educational Boundaries Explain Strength and Variation in Global Fertility Convergence.” Scientific Reports 14:27323.

This paper shows that the level and timing of fertility are converging strongly over different measures of educational attainment using 65 years of data from 146 countries. Global convergence patterns are primarily driven by high-income societies, while sub-Saharan Africa is the world region that is converging most slowly, if not converging at all. Most importantly, levels of education matter heavily for explaining strength and variation in global fertility convergence, with two intersecting educational gradients suggesting: (i) stronger convergence over tertiary education followed, in turn, by secondary and primary; (ii) stronger convergence over education completed relative to education attended. Our findings provide important insights for addressing key challenges in global development and demography, and for informing policymakers as they evaluate the suitability of specific educational policies aimed at further narrowing inequalities between societies—such as supporting higher education as well as the successful completion of targeted educational cycles.

Wu, Hanbo. 2022. “The Effect of Maternal Education on Child Mortality in Bangladesh.” Population and Development Review 48(2):475–503.

This paper examines the effect of maternal education on child mortality in Bangladesh by exploiting quasi-experimental variations in the duration of exposure to a school stipend project for identification. Results from the instrumental variable estimation indicate that an additional year of maternal schooling reduces both under-five and infant mortality by about 20 percent. The findings are statistically significant and robust to a number of model specifications, including survival models controlling for right censoring of child mortality. Analysis of potential mechanisms suggests that maternal education reduces child mortality through greater wealth and literacy, positive assortative mating, lower fertility, delayed marriage and childbearing, greater health-related knowledge, better health-seeking behaviors, and female empowerment, but not through female employment.

Wu, Hanbo. 2021. “Maternal Stress and Sex Ratio at Birth in Sweden over Two and a Half Centuries: A Retest of the Trivers–Willard Hypothesis.” Human Reproduction 36(10):2782–2792.

STUDY QUESTION: Is there a negative relationship, as predicted in the Trivers–Willard hypothesis (TWH), between the intensity of maternal stress and sex ratio at birth (SRB).SUMMARY ANSWER: Using a comprehensive data set with multiple indicators of maternal stress, most measures of stress show no statistically significant association with SRB over a period spanning 243 years, indicating no support for the TWH. WHAT IS KNOWN ALREADY: Evolutionary biologists have proposed a widely discussed hypothesis that women in poor and stressful conditions during pregnancy are more likely to give birth to girls, and exposure to stressful events may therefore lead to a reduction in sex (male-to-female) ratio at birth. The empirical evidence so far is mixed. STUDY DESIGN, SIZE, DURATION: Annual time series data, spanning 243 years between 1749 and 1991 for Sweden at the national level, were drawn from multiple sources. The outcome is defined as the percentage of male births relative to all births in Sweden in a given year. The covariates include a set of economic and climatic variables as proxies for maternal stress. PARTICIPANTS/MATERIALS, SETTING, METHODS: We conduct a series of ARIMA (autoregressive integrated moving average) models to examine the relationship between maternal stress and SRB during three periods: 1749–1991, 1749–1861 and 1862–1991. MAIN RESULTS AND THE ROLE OF CHANCE: In 1749–1991, economic proxies for maternal stress showed no statistically significant association with SRB. In 1749–1861, two indicators were significantly associated with SRB, but the coefficients were opposite in direction to the TWH. In 1862–1991, five out of six covariates showed no significant association with SRB. An additional analysis found no significant correlation between sex ratio of stillbirths and all covariates in 1862–1991. Our results are incompatible with the TWH and suggest that previous findings in support of the TWH are not robust. LIMITATIONS, REASONS FOR CAUTION: This study provides population-level evidence that may not necessarily reflect the nature of all individuals due to the ecological fallacy. The time series analysed in this study are annual data, and we cannot examine the potential seasonality due to the lack of disaggregated monthly data. Our findings may not be generalised to the contexts of extreme maternal stress conditions such as famine and war. WIDER IMPLICATIONS OF THE FINDINGS: The results from existing studies in this topic may be speculative, and additional research with more comprehensive design, data and covariates is needed to reconsider the robustness of previous findings.

Working Papers

Pesando, Luca Maria, Hanbo Wu, Ewa Batyra, and Orsola Torrisi. “The (Unintended) Consequences of Changing Polygyny Legislation.” Revise and Resubmit at Demography.

Across Africa, shifts in the legal status of polygyny – from prohibition to liberalization – are rapidly transforming the institutional landscape of marriage. Yet, the effects of these legal reforms and their implications for women’s outcomes remain poorly understood. This study is the first to examine the consequences of recent legislative changes in three diverse African countries (Benin, Kenya, and Nigeria). Drawing on Demographic and Health Surveys (DHS) and employing an event-study design, we find that in Nigeria the legalization of polygyny was followed by an increase in polygynous unions, particularly among rural, less-educated, Muslim women. Conversely, while changes in the legal status of polygyny had limited effects on its incidence in Benin and Kenya – where a ban and a liberalization were, respectively, implemented – we find evidence of changes in decision-making power for women in polygynous unions. In particular, the ban in Benin was associated with a decline in women’s decision-making power, especially regarding household purchases. Conversely, the legalization of polygyny in Kenya was followed by an increase in decision-making power. Our findings provide important evidence of the complex, often unanticipated and divergent consequences of top-down legal reforms into the sphere of marriage. Importantly, they underscore the nuanced and constantly evolving nature of this institution, cautioning against reductive views that depict polygyny as a uniformly oppressive institution perpetuating patriarchal structures.

Wu, Hanbo. “How Do Contradictory Policies Reshape Educational and Labor Market Outcomes? The Case of Education Reforms in Vietnam.” Revise and Resubmit at Research in Social Stratification and Mobility.

At the turn of the 1990s, the Vietnamese government launched two education reforms: a secondary school tuition fee system that increased the costs of education and a compulsory primary schooling law that reduced barriers to education. I examine how these two contradictory policies reshape educational and labor market outcomes, with a focus on individuals who were exposed to both policy shocks. I find that tuition fee reform decreases individual years of schooling, while compulsory schooling law increases it. For those exposed simultaneously to both policies, the beneficial effect of the latter outweighs the adverse effect of the former, resulting in an overall improvement in educational attainment. This favorable joint effect is especially pronounced among disadvantaged groups, such as rural residents, women, and ethnic minorities. Moreover, the two policies together enhanced intergenerational educational persistence, but their effects on labor market outcomes are less consistent. These findings advance our understanding of how the interaction of concurrent policies reduces or reinforces socioeconomic inequality.

Wu, Hanbo. “Gender Revolution amid Gender Inequality? Uncovering the Multidimensional Complexity of Gender Ideology in Contemporary India.” Under Review.

Sociologists have challenged the assumption that gender ideology falls along a single continuum with traditionalism at one end and egalitarianism at the other. Using latent class analysis with nationally representative data, this article is the first to document the multidimensional structure of gender ideology in India, where gender inequality is a profound and prolonged issue. I find that fully egalitarian class and traditional class account for 8% and 19% of the sample, respectively, while the rest of the sample are divided into four classes that combine traditionalism and egalitarianism in different domains, reflecting the widespread multidimensionality of gender ideology in modern India. In particular, I show that individuals in these ambivalent classes generally favored the dual-breadwinner model, women’s participation in household decision-making and politics, and men’s involvement in domestic work. But at the same time they held traditional beliefs emphasizing male primacy in intimate relationships, labor market, and cultural traditions like handling parents’ funerals. The findings indicate some signs of gender revolution taking place in India, but social norms enhancing patriarchy made configurations of gender role attitudes rather complex.

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