There is a paradigm shift in science at present that indicates that the onset of many diseases, including reproductive diseases and dysfunctions, are already programmed in utero or in the early postnatal period. This new field is called the developmental basis of health and disease. Although focus has been on the role of in utero nutrition and its effects on subsequent adult-onset diseases, it is clear that exposure to environmental stressors/toxicants in utero or during early development can also increase susceptibility to disease later in life. The mechanism for this in utero and early developmental effect is thought to be altered epigenetic control of gene expression, which alters developmental programming and results in a tissue that may appear normal but is functionally compromised. Although this concept is still a hypothesis, this review addresses the current state of data relating to proving its importance and role in reproductive diseases. If the developmental basis of disease is shown to be true, then examination of the etiology of disease and prevention and intervention strategies will need to be modified to fit the new paradigm.