The placenta is divided into anterior and posterior walls, with the posterior wall being a normal location for the placenta, which is unrelated [to preterm birth]. Generally, there is a hereditary tendency for preterm birth, and it is more likely to occur in individuals with certain physical constitutions or in cases of twin pregnancies. Additionally, people with gestational diabetes are also prone to preterm birth. Therefore, the posterior wall of the placenta has no correlation with preterm birth. Conditions like placenta previa or premature placental detachment are placental positions that can lead to preterm birth issues, and some people may experience preterm birth under these circumstances.