The fetal membranes are the external structures that protect and ensure the viability of the fetus during intrauterine development. The presence of fetal membranes is one of the main signs that the fetus belongs to a living embryo or fetus. If the outer membranes cease to exist, it can lead to fetal death and complications during pregnancy.
The formation of the fetus occurs over several months, during which the fetal tissues are covered with more and more new membranes. This process begins already in the early stages of pregnancy and continues until the moment of birth. In total, there are 4 layers of the membrane: amniotic membrane, chorionic membrane