Fetal head articulation, also known as fetal head entry, describes the process of fetal descent toward the maternal pelvis and is one of the requirements for natural vaginal delivery of the fetus. Fetal head articulation means that the biparietal diameter of the fetal head enters the pelvic inlet plane during labor, and the lowest point of the fetal head skull is close to or reaches the level of the sciatic spine, usually the fetal head enters the pelvic inlet in a semi-prone flexed state, articulating with the occipital frontal diameter. Most primiparous mothers are articulated 1-2 weeks before the expected date of delivery, and menstruating mothers are articulated after the start of labor, but there are individual differences between each woman and the time of articulation will be relatively different. If there is less movement, the fetal head articulation will appear relatively late in the pregnancy and may occur after the formal labor. However, if the fetal head is still not in the pelvis after the official delivery, cephalopelvic disproportion, oversized fetus or maternal pelvic abnormalities are considered. It is recommended to check the ultrasound for umbilical cord bypass, biparietal diameter and measure the pelvic diameter to see if the pelvis is small. If there is cephalopelvic disproportion, a cesarean delivery should be considered.