Baby station refers to the relationship of the top of the baby’s head or the presenting part to the level of the ischial spines. Baby station is measured by vaginal exams by your health care provider. Your doctor can feel two bony prominences through the vaginal wall. It is called ischial spines. Baby station is measured in positive and negative numbers. These numbers is measured in centimeters. For example -5 is a floating baby and +5 is crowning.
Baby station numbers:
1. Negative numbers during labor: If the baby’s head is above the ischial spines it is a negative number. For example -1 means baby’s head is 1 centimeters above the spines and -2 means baby’s head is 2 centimeters above the ischial spines. Negative numbers above -3 means fetal head is unengaged or floating.
2. Positive numbers during labor: If the baby’s head is below the ischial spines it is a negative number. For example +2 means baby’s head is 2 centimeters below the ischial spines. +1 means baby’s head is 1 centimeters below the ischial spines. Positive numbers above +3 to +5 means fetal head is crowning and it is time to deliver the baby.
3. Zero station: 0 station means the top of the fetal head is said to be engaged in the pelvis. Fetal head is engaged, because the widest portion of the fetal head has entered the opening of the birth canal.
4. Engagement: Women have their first baby describe deep engagement 0 or +1 for weeks prior to the onset of labor. Women who have 2nd or 3rd baby may not engage below -2 until they are in labor.
The station of the baby refers to the progress of the baby through the pelvis. Your doctor will try to estimate where the baby’s head is in relation to the ischial spines of the pelvis. Sometimes they will also use a cervial exam to determine the position of the baby.