At what gestational week do fetal kidneys begin to produce urine?

Fetal kidneys begin to produce urine around the 16 to 17-week gestation period. This process is a significant milestone in fetal development, as the production of urine contributes to the amniotic fluid volume, which is essential for fetal lung development and overall growth. Before this stage, the fetal kidneys undergo development and maturation, but they do not start functioning in terms of urine production until the specified gestational weeks. This capability is critical for the maintenance of a healthy intrauterine environment, and it reflects the progressive complexity of fetal organ systems as the pregnancy advances.