Placental thickness in late pregnancy

The late pregnancy is a critical period for everyone, because the woman will soon be about to give birth, so the body may encounter various problems at this time. The thickness of the placenta in the late pregnancy determines the state of the child's development in the uterus. Some relevant knowledge about the placenta requires a correct understanding and comparison to know what kind of grading of the placenta is?

The placenta is a transitional organ that grows from the embryo's embryonic membrane and the mother's endometrium during pregnancy in metatherian and eutherian mammals and is used to exchange substances between mother and child. The fetus develops in the uterus and relies on the placenta to obtain nutrition from the mother, while both parties maintain a considerable degree of independence. The placenta also produces a variety of hormones to maintain pregnancy and is an important endocrine organ.

Some reptiles and fish also reproduce by giving birth to their offspring live. The embryo grows some auxiliary structures such as yolk sac and gill filaments that are closely integrated with the maternal tissues to achieve the exchange of substances between mother and child. This structure is called a pseudoplacenta.

There are two independent circulatory systems in the placenta, one for the fetus and the other for the mother (even if it develops to the sinusoidal endothelial type, such as in the late rabbit embryo, there is still a layer of endothelial cells separating the two sides). The chorion can be regarded as a semipermeable membrane, and the area in which all the villi are in contact with the maternal blood is 7 to 14 square meters; when the maternal blood flows in the gaps between the villi and the fetal blood flows in the villi, substances can be exchanged.

Ultrasound grading of the placenta

Placental ultrasound grading is one of the important indicators for evaluating placental function. The placenta is divided into four grades, namely 0, I, II, and III, according to the echo and morphology of the chorionic plate, placental parenchyma and basal plate at different stages of pregnancy. This is a method that relies on the different grayscales of ultrasound images to make judgments with the naked eye. It is somewhat subjective and there are certain differences between different operators.