Tim Cejka

Using administrative tax records, two large-scale nationally representative surveys, and a purpose-built household survey from Pakistan, we estimate the long-run effects of prenatal Ramadan fasting. Maternal fasting reduces birth weight, educational attainment, and adult earnings, with average ATT effects approximately 2.5 times larger than ITT estimates. We document three novel findings. First, exposure and fasting rates do not vary by socioeconomic status, yet impacts concentrate among poorer households, implying a poverty penalty in consequences of early-life shocks. Second, exposure transmits intergenera-tionally through both maternal and paternal lines. Third, effects vary by trimester in patterns consistent with developmental biology. Back-of-the-envelope calcula-tions suggest this single mechanism permanently lowers Pakistan's steady-state GDP by approximately 1.5% or by $5.6 billion annually.