The term fetal station can be a hard term to grasp and truly understand. Let’s dig into this often poorly explained mystery and see if we can outline some clear, hard facts and demystify the definition.
Station refers to how far down the baby's head has descended into the mother's pelvis. It is measured from -5 to +5.
The 0 point of this measuring stake is the ischial spines. Simply put, the ischial spine is (usually) the most narrow part of the pelvis.
See the pointy spines that protrude toward the middle of the pelvis that the dotted line is running through? Those are the ischial spines. That is the 0 mark. When baby’s head is above that imaginary line, it is called unengaged and can be measured from -5 (5 centimeters above the ischial spines) to -1 (1 centimeter above the ischial spines).
If baby’s head is higher than a -5 station, it is called “floating”.
When the top of baby’s head reaches the 0 station, it is called engaged. This can happen any time during the last month of pregnancy or even during labor.
Once the baby’s head moves past the ischial spines, it is measured from +1 (1 centimeter past the spines) to +5 (crowning).
Ischial spines = narrowest part of the pelvis
Station is measured in relation to the ischial spines, with negative numbers being above and positive numbers below the ischial spines.
The purpose of measuring baby’s station is to tell how far through (or above) the pelvis baby is.
Birth terms can be intimidating and confusing, but usually they are quite simple when broken down. In my next article on birth terms we’ll talk about another commonly confused definition!