Figure 2, Key Figure. Impact of glucocorticoids on reproductive physiology.

The impact of glucocorticoids on reproductive physiology is dependent on dose and timing. Both excess and insufficient levels of glucocorticoids result in reproductive dysfunction, though occurring through differing pathophysiology. The timing of exposure also dictates the relative benefit or harm of glucocorticoid exposure. The example is provided in which early exposure to high levels of glucocorticoids may inhibit endometrial receptivity, although physiological levels of glucocorticoids may be required for this process. Excess glucocorticoid exposure during early is associated with reduced placental weight and fetal size. However, glucocorticoid signaling in the third trimester is required for fetal development. Timing of exposure also plays a role in fetal programming of postnatal development, with more profound influence occurring as a result of elevated glucocorticoids during the first and second trimester.