In plain words
Dilation is the widening of the cervix, the neck of the uterus, during labor. It is measured in centimeters, from zero, which is closed, to ten, which is fully open. A provider checks dilation with a gentle exam. Dilation often happens gradually over many hours, and it can speed up in . Some mothers are told a number early and then find the progress slower than expected. Dilation is one sign of labor, but it is not the only one. Contractions, the baby's position, and the mother's comfort all matter. A check is a snapshot, and many people stay at the same number for a time. Asking the team what the numbers mean in a specific birth can help the mother feel more in the know.
The deeper version
Cervical dilation is the progressive opening of the internal os during the first stage of labor. Friedman (American Journal of Obstetrics and Gynecology, 1954) described the sigmoid labor curve in primiparas, establishing the active phase starting near 4 centimeters and an expected rate of dilation that later studies revised. Zhang and colleagues, from the Consortium on Safe Labor (Obstetrics and Gynecology, 2010), documented contemporary patterns in spontaneous labor with normal neonatal outcomes, showing slower early dilation and a later active phase than the . ACOG Practice Bulletin 49 (2003) on dystocia and set criteria for abnormal progress. The main controversy concerns labor duration thresholds and whether using a curve to define arrest increases intervention rates.
Where it comes up
What mothers here say about dilation
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Sources
- Zhang J et al., Consortium on Safe Labor — Contemporary patterns of spontaneous labor with normal neonatal outcomes. Obstetrics and Gynecology, 2010
- Friedman EA — Primigravid labor: a graphicostatistical analysis. American Journal of Obstetrics and Gynecology, 1954