What is the common position of the fetus in vertex presentation?

In vertex presentation, the common position of the fetus is head down. This means that during labor, the baby's head is the first part to enter the birth canal. This position is the ideal and most common for vaginal delivery as it allows the widest part of the baby's body, the head, to present first, facilitating a more straightforward delivery process. Being in a head-down position allows the baby to navigate the curves of the mother's pelvis more effectively during labor, promoting safety for both the mother and the fetus. This is contrasted with other presentations, such as feet first, sideways, or shoulder down, which can complicate delivery and may necessitate alternative interventions such as cesarean delivery.