A fetus with a biparietal diameter of 9.0cm is probably after 37 weeks of gestation and weighs about 2800g, but it is not absolute and there are differences between individuals. Fetal biparietal diameter refers to the length of the widest part of the fetus between the right and left sides of the head, biparietal diameter 9.0cm fetus is mostly after 37 weeks of pregnancy, weighing about 2800g. Biparietal diameter to determine the size of the development of the fetus, is a reference data, calculated weight, is only a rough calculation of the value, there will be a certain degree of error, the development of each fetus is not the same, there are differences is normal. More than 37 weeks of the fetus that is full-term, the biparietal diameter of 9cm is a normal phenomenon, but also do a good job of pregnancy and obstetrics to observe every week, the fetal head circumference will continue to grow, easy to labor and delivery of difficult phenomena. After pregnancy to do a good job of pregnancy obstetric examination, can be specific understanding of the normal development of the fetus in the uterus.