What typically occurs due to renal agenesis?

The occurrence of renal agenesis, a condition where one or both kidneys fail to develop, typically leads to the compression of fetal structures. This is primarily due to the reduced amount of amniotic fluid, a result of decreased urine output from the absent or underdeveloped kidney. In fetal development, amniotic fluid is crucial for cushioning the baby and allowing space for normal growth. When there is less amniotic fluid, as often seen in renal agenesis, the outward pressure on the surrounding fetal structures can lead to various complications, including limb deformities and facial deformities.

While other choices may seem plausible in a general context, they do not align with the physiological implications of renal agenesis. There is no development of additional kidneys, as the condition specifically involves the failure of kidney development. Moreover, urine output is decreased rather than increased, and fetal swallowing is not enhanced in this situation due to the lack of amniotic fluid. Thus, the compression of fetal structures is the most characteristic and significant consequence of renal agenesis.