Sikiöajan

Sikiöajan refers to the fetal stage of development, which begins after the embryonic period and continues until birth. In humans, this period typically spans from the ninth week of gestation to the time of delivery. During the fetal stage, the major organs and body systems that were formed during the embryonic period continue to grow and mature.

The fetal stage is characterized by rapid growth in size and weight. Organs become more complex and begin to function. For example, the digestive system starts to produce digestive juices, and the kidneys begin to excrete urine. The nervous system continues to develop, with the brain growing significantly and developing more intricate connections.

By the end of the fetal stage, the fetus has a recognizable human form. External features like fingers, toes, and facial features are fully developed. Internal organs are in place and increasingly capable of performing their functions. Movement becomes more pronounced as muscles develop, and the fetus may start to kick and turn.

The length of the fetal stage can vary, with full-term pregnancies typically lasting around 40 weeks from the last menstrual period. Premature birth occurs when a baby is born before 37 weeks of gestation. The fetal stage is a critical period for the development of a healthy, viable infant.