Publications
Works in Progress
- Working PaperHow, When, and Where Does the Opportunity Gap Open Up in the Netherlands?In , 2026
We use administrative data on a wide range of outcomes, measured between birth and the age of 35, of 4.6 million children and their parents, to document three sets of results on intergenerational mobility in the Netherlands. First, we show that the opportunity gap in the Netherlands opens up at a very young age and that many of our 55 measures of health and wellbeing, education, work and income, and housing are strongly associated with parent income, wealth, and educational attainment. These differences persist from birth through adulthood. At the top (90th percentile) of the parent income distribution, children are on average 42% less likely to be small for gestational age at birth, 396% more likely to obtain a high primary school test score, 351% more likely to attend university, 75% less likely to experience young parenthood and 65% less likely to claim disability benefits at the age of 35, and compared with children at the bottom (10th percentile) of the parent income distribution. On average, a 10 percentage point increase in parent income is associated with a 2.8 percentage point increase in a child’s income. This means that the Netherlands has the lowest relative intergenerational income mobility of all developed countries for which this was measured, after the U.S. and the UK. Second, we document substantial spatial variation in the degree of absolute income mobility, measured as the mean income rank of 35-year-old children of parents at the 25th percentile of the parent income distribution. The distribution of absolute mobility across neighborhoods in the Netherlands is narrower than in the U.S. Third, we correlate our estimates of absolute upward mobility with various municipal-level characteristics and find higher rates of upward mobility in rural areas than in urban areas, lower rates of upward mobility in areas with a high share of voters on the left of the political spectrum, and lower rates of upward mobility in areas characterized by greater neighborhood and classroom segregation. We make our results publicly available as data sets and through two interactive websites, https://opportunitygap.nl/ and https://opportunitymap.nl/.
@incollection{lam2026mobility, title = {How, When, and Where Does the Opportunity Gap Open Up in the Netherlands?}, author = {Lam, Helen and Ravesteijn, Bastian and Van De Kraats, Coen and Van Kesteren, Erik-Jan}, year = {2026}, } - Working PaperImproved Targeting to Prevent Adverse Birth Outcomes using Big Data in the NetherlandsHelen Lam, and Bastian RavesteijnIn , 2026
A strong link has been documented between adverse birth outcomes and compromised health from early childhood to adulthood. Hence, policymakers may consider targeting their policies toward specific geographic areas and demographic groups with a high incidence of adverse birth outcomes. In this paper, we document the association between adverse birth outcomes and a wide range of sociodemographic circumstances by linking the universe of all 1,500,690 births in the Netherlands between 2008 and 2016 to administrative data on home addresses, household incomes, and migration backgrounds of parents. We present three sets of results. First, birth outcomes in the Netherlands vary substantially by parental income: 19.1 percent of low-income births are small-for-gestational-age (SGA) versus 8.5 percent of high-income births; 8.2 percent of low-income births are preterm versus 5.5 percent of high-income births; and the infant mortality rate is 1.1 percent among low-income births versus 0.4 percent among high-income births. Second, we observe substantial geographic variation in birth outcomes among low-income parents, defined as parents with an income at the 25th percentile of the parental income distribution, or € 54,365. When compared to low-income parents in the geographic center of the Netherlands, parents with a similar income in the former mining zone in the southeast of the Netherlands were twice as likely to experience SGA births (18.4 percent versus 8.9 percent, respectively), 1.8 times more likely to experience premature births (10.3 percent versus 5.8 percent), and 2.8 times more likely to face infant mortality (1.04 percent versus 0.37 percent). Third, areas where low-income parents are more likely to experience adverse birth outcomes are characterized by relatively large shares of Roman Catholic and Muslim, but not Protestant Christian, residents; large shares of residents with an immigrant background; and large vote shares for two populist parties on the left and the right of the political spectrum. Controlling for parental income, strong geographic variation in birth outcomes persists in the Netherlands. We have developed two publicly available interactive websites to help policymakers and health professionals in targeting these policies and interventions in the Netherlands. Furthermore, we have compiled a publicly available dataset that can be used by other researchers to examine the determinants of adverse birth outcomes.
@incollection{lam2026adverse, title = {Improved Targeting to Prevent Adverse Birth Outcomes using Big Data in the Netherlands}, author = {Lam, Helen and Ravesteijn, Bastian}, year = {2026}, } - Working PaperHow Neonatal Health Shapes Human Capital: Evidence on Developmental PathwaysHelen Lam, Bastian Ravesteijn, and Hans Van KippersluisIn , 2026
Research consistently shows a strong association between birth weight and a wide range of adult outcomes, but little is known about the developmental pathways from birth through adolescence. This paper examines the relationship between birth weight and longitudinal measures of health and development throughout childhood. We link perinatal care data on the universe of 3.1 million children born in the Netherlands (2000–2020) to novel Preventive Youth Health Care data, providing detailed measures of early-life physical, cognitive, and psychosocial development. We exploit within-family variation in birth weight using sibling and twin fixed effects models. We replicate earlier findings showing that birth weight is significantly associated with early infant health indicators, positively with APGAR score, and negatively with perinatal and neonatal mortality. In terms of developmental pathways, we find lasting effects on physical health (being underweight and overweight), as well as academic performance from ages 11 to 21. In contrast, no to weakly significant associations were found for speech and language development at ages 2 and 3, and socio-emotional development (SDQ score) throughout childhood. Lastly, we find that higher birth weight is associated with lower annual hospital costs, while we find mixed evidence of an association with mental health care use. Overall, the findings highlight the lasting consequences of neonatal health conditions and point to specific pathways through which in utero conditions affect human capital outcomes.
@incollection{lam2026birthweight, author = {Lam, Helen and Ravesteijn, Bastian and Van Kippersluis, Hans}, title = {How Neonatal Health Shapes Human Capital: Evidence on Developmental Pathways}, year = {2026}, }
Other Publications
- BookchapterUrgentie: zwangerschap en kansenongelijkheid op de KansenKaartHelen Lam, and Bastian RavesteijnIn Sociale verloskunde, 2021
Kansenongelijkheid ontstaat al vóór de geboorte. In de literatuur is inmiddels veel bekend over de verbanden tussen zwangerschapsuitkomsten, sociaaleconomische status van ouders en de plek waar ouders wonen. In dit hoofdstuk kijken we naar twee zwangerschapsuitkomsten die sterk samenhangen met gezond- heid en ontwikkeling in het latere leven: een laag geboortegewicht en vroeggeboorte. De resultaten in dit hoofdstuk zijn gebaseerd op ons KansenKaart-onderzoek, waarmee wij kansenongelijkheid binnen Nederland letterlijk in kaart brengen. Naast zwangerschapsuitkomsten toont de KansenKaart een groot aantal andere uitkomsten op het gebied van gezondheid, onderwijs en economische productiviteit.
@incollection{lam2021inequality, author = {Lam, Helen and Ravesteijn, Bastian}, title = {Urgentie: zwangerschap en kansenongelijkheid op de KansenKaart}, editor = {E. A. P. Steegers, A. Waelput, P. Peeters}, booktitle = {Sociale verloskunde}, publisher = {Bohn Stafleu van Loghum}, year = {2021}, pages = {49-60}, chapter = {3}, }