The First 1000 Days of Life Determine Health for a Lifetime

The first 1000 days of life, from conception to two years of age, have become the most determinant period in the human biological architecture. Factors such as nutrition, stress, the social environment, and epigenetic changes in the egg and sperm decisively influence development. This concept has been supported by large-scale historical studies, such as the Dutch Hunger Winter during the Nazi occupation between 1944 and 1945, the siege of Leningrad, and the Chinese food crisis between 1959 and 1961. Decades later, people exposed to malnutrition during the perinatal period showed a greater predisposition to obesity, diabetes, hypertension, and cardiovascular disease. Changes in diet and the incorporation of physical exercise in women with obesity significantly reduced metabolic damage in their children, confirming that early programming is not irreversible. The DOHaD approach establishes that we are not just genetics, but the result of the interaction between genes and environment from very early stages. This forces the kidney to work under overload throughout life, which increases the probability of hypertension and kidney disease at an early age. The work directed by Zambrano González provided high-impact experimental evidence by demonstrating that insulin resistance can be transmitted transgenerationally, even when children receive adequate nutrition throughout their lives. Their animal models confirmed that maternal obesity leaves a persistent metabolic footprint, associated with less longevity and a higher risk of metabolic disorders in offspring, even under controlled diets. At the same time, their studies showed that intervening before pregnancy or during gestation can modify this biological destiny. Within this framework, the research of Elena Zambrano González, a professor at the Faculty of Chemistry of UNAM and the Department of Reproductive Biology of the National Institute of Medical Sciences and Nutrition Salvador Zubirán (INCMNSZ), has demonstrated that the nutrition, environment, and metabolic state of the parents—especially the mother—can program the health, disease, and life expectancy of the offspring and even of future generations. This field of knowledge, known as Developmental Origins of Health and Disease (DOHaD), has transformed the way modern medicine understands the appearance of chronic diseases, aging processes, and biological inheritance. The stage that defines all of life From a scientific perspective, the first 1000 days constitute a critical window of biological plasticity, in which the developing organism adjusts its organs, systems, and metabolism to the conditions of the environment. If that environment is adverse—due to malnutrition, maternal obesity, stress, or nutritional deficiencies—those adaptations can become permanent risk factors. One of the clearest examples is observed in renal development. Humans are born with about one million nephrons per kidney, but when the mother goes through severe malnutrition or metabolic instability, the fetus can develop with fewer functional units. The first 1000 days emerge as the most critical stage of human development.