The lower edge of the placenta covers the internal cervical os. Before 28 weeks of gestation, this condition is referred to as a low-lying placenta, while after 28 weeks, it is termed placenta previa. It is one of the most common causes of vaginal bleeding in the third trimester and one of the serious complications of pregnancy. The exact etiology is not entirely clear, but it is associated with several factors.1. Placental abnormalities, such as abnormal shape or size, may lead to placenta previa. For instance, the incidence of placenta previa is twice as high in twin pregnancies compared to singleton pregnancies.2. Endometrial lesions or damage, such as from cesarean sections or previous uterine surgeries, which can cause endometritis or atrophic changes, may increase the risk of placenta previa.3. Delayed development of the trophoblast layer of the fertilized egg can also contribute to placenta previa.4. In vitro fertilization (IVF) and the use of ovulation-inducing drugs, which alter hormonal levels, can cause asynchronous development of the endometrium and embryo, leading to implantation in the lower uterine segment and subsequent development of placenta previa.