Human Fetus at 21 Weeks in the Womb (Asian Skin)

Description

A fetus of approximately 21 weeks gestational age floats in a lateral, flexed posture within the translucent amniotic sac, suspended in amniotic fluid. The head remains proportionally large relative to the trunk, with the frontal bossing of the cranial vault, closed eyelids, a formed nasal tip and lips, and a clearly modelled external ear (auricle) against the side of the skull. One hand is drawn up toward the mouth with individual digits distinguishable, while the lower limbs are flexed at the hips and knees and the feet cross in front of the body. The umbilical cord inserts at the umbilicus and displays the spiral of two umbilical arteries around the single umbilical vein, coursing posteriorly to the placental disc seated on the vascular uterine wall. Week 21 sits within the mid-second-trimester window in which detailed anatomical ultrasound survey is performed, making this the reference appearance for biparietal diameter, head and abdominal circumference, femur length, and assessment of the limbs, face and profile. The rendering also illustrates structures central to obstetric care: cord coiling and vessel number, placental site relative to the uterine wall, and amniotic fluid volume surrounding the fetus. Fetal movement, swallowing and hand-to-mouth activity are established by this stage, and the periviable threshold approaches only in the weeks that follow, which shapes counselling around preterm birth. The image supports obstetric and midwifery teaching, embryology and developmental anatomy courses, and antenatal classes where expectant parents follow week-by-week growth. It works equally well as a figure in textbooks and journal articles, in ultrasound training material comparing sonographic planes with true fetal anatomy, and in clinic displays, apps and pregnancy publications produced by health agencies. Presented as one frame of a continuous weekly series, it allows direct visual comparison with adjacent gestational ages. Anatomical accuracy verified by SciePro's Medical Advisory Board.