La estación se refiere a hasta qué punto abajo en el canal del parto el bebé ha viajado y es medido desde -3 hasta +3.
https://muyfitness.com/que-significa-tener-el-60-borrado-el-...

Fetal station is a measurement of how far the baby has descended in the pelvis, measured by the relationship of the fetal head to the ischial spines (sit bones).Jun 21, 2019
Your Baby's Fetal Station in the Pelvis - Verywell Family
https://www.verywellfamily.com/your-babys-station-2759017

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Note added at 14 mins (2019-07-25 15:20:25 GMT)
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Station

During the last month, your doctor will estimate how far the baby's head has moved down into (engaged) the pelvis. This is measured in "stations." A baby is at –3 station when the head is above the pelvis and at 0 station when the head is at the bottom of the pelvis (fully engaged). The baby is at +3 station when the head is beginning to emerge from the birth canal (crowning).
https://myhealth.alberta.ca/Health/pages/conditions.aspx?hwi...

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Note added at 1 hr (2019-07-25 16:28:11 GMT)
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So in this case, "Estación: f-3" means that the baby is at -3 station. I imagine the f stands for feto: I have found examples of fetus but I think "baby" is the term used here:
"examination revealed the patient to be 1 cm. dilated, 80% effaced, and the fetus at -3 station."

Dilation, Effacement, Station | MedTwice
https://medtwice.com/dilation-effacement-station/
Jun 4, 2012 - A baby at -3 station is still very high in the pelvis and not close to delivery. If the baby's head is at +4 station it is essentially delivered.

"She was 1 cm dilated and 50% effaced, with the baby at -3 station."

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Note added at 1 hr (2019-07-25 17:03:03 GMT)
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+3 makes more sense.