What does a placenta thickness of 28 mm mean?

During pregnancy, pregnant mothers need to check many indicators to judge the development of the fetus. The thickness of the placenta will change with the duration of pregnancy, and the thickness of the placenta has different standards in different periods. If the placenta is too thick or too thin, you should pay attention to your daily nutritional intake. So, what does a placenta thickness of 28mm mean? This indicates that the pregnant mother is in the second trimester of pregnancy.

The normal [full-term] placental thickness measured by B-ultrasound is 3.6-3.8 cm, usually not exceeding 5 cm. Under abnormal circumstances, the placenta may be enlarged. Conditions such as blood type incompatibility and diabetes can cause the placenta to be thicker than 5cm. Placental thickening generally indicates complications of the pregnant woman and some abnormalities in the growth of the fetus in the uterus. (The normal thickness of the placenta during pregnancy should be between 25 and 50 mm) The membranous placenta is characterized by a large and thin placenta, which is prone to bleeding in the second trimester of pregnancy. If the placenta is small, it can lead to intrauterine growth retardation of the fetus and low birth weight at full term.

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.