The placenta is located at the lower edge of the posterior wall about 19mm from the endocervical opening at 16 weeks of pregnancy.

At 16 weeks of pregnancy the placenta is located on the lower edge of the posterior wall about 19mm from the endocervical opening at this point in gestation there is no danger, but the pregnant woman should have regular obstetric examinations to observe the placenta.
The placenta is attached to the lower part of the uterus, and the edge is less than 2cm from the endocervical opening as hypoplastic placenta. If the placenta is found to be low in the middle of pregnancy, it usually does not need special treatment, and there is no danger to the pregnant woman at this time. However, it is considered an abnormal situation, and pregnant women should pay attention to the changes of the placenta during the labor and delivery examination afterwards.
Generally with the increase of pregnancy weeks, the lower part of the uterus gradually stretches, and the situation of placenta hypoplasia will improve. However, it is also possible that the placenta will gradually move towards the cervical opening. If the lower edge of the placenta reaches or covers the opening of the cervix after 28 weeks of pregnancy, it is classified as placenta praevia, which can have an effect on the pregnancy and labor.
Pregnant women should undergo regular checkups during pregnancy. If there is any abnormality, they need to consult a doctor and take care of it under the doctor’s guidance.