Pregnancy check at four months said it was a contour-shaped placenta, what does this mean?

Patient's question:

No

Doctor's answer:

Hello! A is an abnormal and special structure of the placenta. At the edge of the placenta, the chorion and amnion roll into a yellow ring. The blood sinuses at the edge of the placenta are particularly weak, making them prone to rupture and causing bleeding. The impact on the fetus may include conditions such as fetal intrauterine hypoxia, so it is important to undergo regular prenatal check-ups and follow the doctor's guidance to take preventive measures.