17 weeks pregnant placenta position anterior wall is normal, but the thickness of 20mm is not normal, pregnant women need to pay attention. Anterior placenta in 17 weeks pregnancy means that the placenta is attached to the anterior wall of the uterus, which is a normal phenomenon. Usually the placenta can also be attached to the side wall of the uterus, the posterior wall, etc., do not need to worry too much. For 17 weeks pregnant placenta thickness 20mm, is an abnormal phenomenon, normal pregnancy placenta thickness between 2.5 ~ 3.8cm, mainly related to the degree of nutritional intake, physical fitness. For 17 weeks placenta thickness of 20mm, consider the placenta is too thin, may be related to abnormal hormone levels during pregnancy, the placenta area is too large and other factors, easy to affect the supply of blood and oxygen to the fetus, and even on its growth and development, so pregnant women need to pay attention. It is recommended that the placenta in the 17th week of pregnancy with a thickness of 20mm should be further examined in detail, so that the doctor can take measures according to the actual situation.