This study uses maternal fasting during the Islamic holy month of Ramadan as a natural experiment for evaluating the long-term effects of prenatal nutrition. Because the timing of Ramadan varies by year, we can disentangle the effect of fasting from seasonal effects (e.g. weather, virus exposure). We use the 2002 Uganda Census which collects information on a range of adult outcomes (e.g. disability, education, illiteracy) for a large sample of Muslims and non-Muslims. We find the occurrence of Ramadan nine months before birth increases the likelihood among Muslims of having a disability in adulthood by 20 percent (p =0.03). Effects are found for blindness, deafness, disability involving the lower extremities, and mental retardation. No corresponding effect is found among non-Muslims. We also find that cohorts exposed to Ramadan in utero had lower sex ratios (fewer males relative to females). This suggests maternal fasting may increase attrition of male fetuses and is consistent with previous studies linking maternal famine exposure to reductions in the sex ratio. We find no evidence that negative selection in conceptions during Ramadan accounts for our results.
--Douglas Almond and Bhashkar Mazumder, "Prenatal Nutrition and Adult Outcomes: The Effect of Maternal Fasting During Ramadan"