Human Fetus at 40 Weeks in the Womb (Asian Skin)

Description

At 40 weeks of gestation the fetus fills nearly the whole uterine cavity, shown here lying on its side within a translucent amniotic sac surrounded by amniotic fluid. The body is held in the characteristic flexed attitude: hips and knees drawn up, arms folded across the chest, hands and feet close to the trunk with fully formed digits, nails and plantar creases. The head is large and rounded, covered with pigmented scalp hair, with well-modelled external ears, closed eyelids and a plump, subcutaneous-fat-filled face and limbs. The umbilical cord loops between the lower limbs, its coiled vessels visible through the covering, and the vascular uterine wall with adjacent placental tissue frames the sac. Term anatomy of this kind underlies obstetric assessment in the final weeks of pregnancy. Fetal lie, presentation and attitude determine the mechanism of labour, and a cephalic presentation with a flexed head presents the smallest suboccipitobregmatic diameter to the pelvic inlet, whereas a non-cephalic lie prompts consideration of external cephalic version or caesarean delivery. The relationship of the cord to the fetal limbs and presenting part is relevant to cord entanglement and to the risk of prolapse when the membranes rupture. Well-developed subcutaneous fat, mature skin and abundant scalp hair are the markers clinicians use to gauge maturity at birth, while the volume of amniotic fluid remains a routine sonographic surveillance parameter. The image suits obstetrics and midwifery teaching on term fetal presentation and the onset of labour, embryology and developmental anatomy courses tracking growth across the third trimester, and antenatal education for expectant parents approaching their due date. Publishers of pregnancy atlases, prenatal apps, ultrasound training resources and clinic waiting-room material can pair it with earlier weeks in the same series to show comparative growth. Anatomical accuracy verified by SciePro's Medical Advisory Board.