The fetal origins hypothesis proposed by Barker (1992) posits that ”certain chronic conditions later in life can be traced to the course of fetal development.” Inadequate in utero nutrition could ”program” a fetus to prioritize brain growth at the expense of
other organs and tissues. Correspondingly, certain chronic health conditions such as diabetes, stroke, and heart problems in middle or old age can be traced back to the fetal environment.
A considerable amount of evidence in the medical literature supports this hypothe-sis. Ozanne and Hales (2004) find that the lifespan of experimental mice is significantly shortened if the postnatal period of growth is accelerated to compensate for reduced growth in utero. Langley-Evans (2001) indicates that poor early fetal conditions result in increased vascular resistance and hypertension. Brown et al. (2004) also suggest that poor early fetal conditions increase the risk of schizophrenia. In addition, epidemio-logical evidence from studies of famine episodes is notable. This series of studies shows that cohorts in utero during the Dutch famine suffered from coronary heart dis-ease morbidity and various other health deteriorations in their middle age (Roseboom et al., 2000; Roseboom et al., 2001; Ravelli et al., 2005).
The fetal origins hypothesis has also attracted the interest of economists. In addi-tion to health condiaddi-tions in adulthood, economists are curious whether early-life health conditions are related to a person’s social and economic outcomes. Case, Fertig, and Paxson (2005) find that a low birth weight and mother’s smoking during pregnancy are related to poor academic achievement and poor health in adulthood. Moreover, health in childhood is associated with adult socioeconomic status.
The aforementioned evidence confirms a strong correlation between early-life health and long-term outcomes. However, it is not easy to determine the causality between them. The main challenge in estimating the effect of early-life health conditions is mainly due to omitted confounders, such as socioeconomic conditions. To cope with this identification problem, Almond (2006) investigates the long-term impact of the 1918 influenza pandemic in the United States. The author uses the abrupt and un-expected attribute of the 1918 influenza pandemic as a natural experiment to test the fetal origins hypothesis. He shows that compared with those born just before or after the epidemic, cohorts in utero during the peak of the influenza pandemic presented
lower educational attainment, lower income, lower socioeconomic status, higher dis-ability rates, and higher transfer payments. Similarly, Schwandt (2014) also finds that in utero exposure to seasonal influenza in Denmark is associated with worse health at birth, a lower labor market participation rate and earnings, and higher rates of welfare dependence.
Chen and Zhou (2007) use a difference-in-differences strategy to test the long-term effects of early-life malnutrition and find that cohorts exposed to the China’s Great Famine in early childhood were significantly shorter, worked fewer hours and had lower income in adulthood. Lee (2014) indicates that prenatal exposure to the Korean War led to lower educational attainment and labor market performance and a higher rate of disability later in life. Moreover, using the difference-in-differences method, Lee finds that the adverse effect of the Korean War was larger for people whose places of birth were more seriously ravaged by the war.
Recently, a series of studies has utilized exposure to malaria as a health shock in early life to clarify the importance of early-life health conditions through different identification strategies. In some of these studies, researchers estimate the malaria risk using epidemiological theories that indicate that malaria risk is principally determined by environmental factors. For example, Hong (2007) utilizes environmental factors such as rainfall, temperature, and elevation to estimate the malaria risk of counties in the United States that do not have reliable data from the 1850s. The author indicates that malaria exposure in childhood resulted in shorter height because of malnutrition and higher susceptibility to infections due to immune disorders.
Barreca (2010) utilizes the instrumental variables strategy to estimate the long-term impact of in utero and postnatal exposure to malaria in the early twentieth-century United States. The author uses variation in ”malaria-ideal” temperatures that are fa-vorable to malaria transmission as an instrument for malaria exposure and suggests that in utero and postnatal exposure to malaria resulted in noticeably lower
educa-tional attainment and higher rates of poverty later in life.1 For example, schooling decreases by close to half a year with ten additional malaria deaths per 100,000, and early-life malaria exposure can explain approximately 25 percent of the difference in long-term educational attainment between cohorts born in malaria-infested states and non-infested states. Chang et al. (2014) employ other climatic factors such as rain-fall, rainy days, relative humidity and wind speed to instrument for malaria deaths.
Combining historical data for Taiwan during Japanese colonization and current data, the authors find that people exposed to a higher malaria risk around their birth period exhibited worse cognitive functions and a higher risk for cardiovascular disease in old age.
Furthermore, a series of studies examines countries that historically suffered from malaria but eliminated the disease early in the twentieth century, and employs pre-eradication geographic variation in malarial intensity within the country and cohort exposure based on the timing of the national anti-malaria campaign. For instance, uti-lizing malaria eradication campaigns in Sri Lanka in the 1940s and in Paraguay in the 1960s as quasi experiments, Lucas (2010) estimates malaria’s effect using a standard difference-in-differences method and demonstrates that malaria eradication increased levels of educational attainment and literacy. Barofsky et al. (2011) also show that malaria eradication in Uganda in the 1950s led to improvements in schooling and lit-eracy. However, Cutler et al. (2010) find that malaria eradication in India in the 1950s had no effect on educational attainment but had a positive influence on economic status for prime-age men. Similarly, Venkataramani (2012) indicates that malaria eradication around the birth year in Mexico in the 1950s resulted in better performance on adult cognition tests and higher consumption expenditures for men, but it had no influence on schooling.2 Bleakley (2010) uses the malaria eradication campaigns in the United
1One concern of this study is whether ”malaria-ideal temperatures” is a sufficiently strong instru-ment. The F-statistic in the first stage is nearly 9.6 in Barreca’s main specification, which to a certain extent mitigates the weak instrument issue.
2The magnitude of the effect for men found by Venkataramani (2012) is larger than that for women,
States, Brazil, Colombia, and Mexico to measure the impact of childhood exposure to malaria on labor productivity. The author shows that, compared with non-malarious areas, cohorts born after eradication had higher income as adults than the former co-horts in malarious areas. Hong (2013) also finds that the anti-malaria campaign in the U.S. in the 1920s was effectual in decreasing work disability later in life.
Table 2.1 summarizes the effects of malaria on education and economic outcomes in the aforementioned research. As Table 2.1 shows, malaria exposure in early life has negative effects on one’s socioeconomic outcomes but has an ambiguous effect on ed-ucational attainment. Moreover, existing studies mainly consider the effect on educa-tional attainment and economic outcomes such as income and poverty later in life, but not on marriage outcomes. To provide more abundant evidence of the importance of early-life health conditions, this paper uses the eradication campaign in Taiwan in the 1950s to estimate the long-term impacts of early-life (in utero and postnatal) exposure to malaria on own educational attainment, income, and spousal educational attainment, which is a marriage-related outcome that has never been discussed in previous studies.
In the next section, we introduce some background information on malaria and the eradication campaign in Taiwan.