As with the relationship between child survival and fertility, the interplay between health and education is complex. As mentioned earlier, more-educated mothers tend to have fewer and healthier children. Moreover, the returns from education in terms of increased wages or agricultural output give heads of households the financial opportunity to promote their own health and that of their children. David Barker, a British physician who noted a correlation between low birth weight and cardiovascular health in midlife, put forward the fetal origins hypothesis that the in utero environment has important consequences for health and cognitive abilities later in life. Several epidemiologists have since confirmed this association. 26 Almond, 27 an economist at Columbia, used the natural experiment of the 1918 Spanish influenza epidemic to assess the impact of fetal health on educational and labor outcomes. Pairing data from the pandemic with those from the 1960 to 1980 decennial US censuses, Almond 27 found that cohorts in utero during the pandemic displayed reduced educational attainment, increased rates of physical disability, lower income, and lower socioeconomic status compared with other birth cohorts. Similarly, Miguel and Kremer 28 analyzed a randomized control trial of deworming in Kenyan schools at the facility level designed to capture the positive externalities associated with reducing the transmission of helminths. Miguel and Kremer 28 found that the program reduced absenteeism from school by one-quarter, although there was no significant effect on test scores. A series of follow-up studies have shown that those who received deworming for a longer period of time enjoy higher wages years later. Taken together, these results suggest that health investments, especially early in life, affect educational attainment.