There is no single dilation measurement that defines active labor, as the transition varies between individuals and pregnancies. However, medical guidelines typically recognize labor progression in stages. Early labor usually begins around 0–3 centimeters of cervical dilation, often with irregular contractions. Active labor is generally considered to begin around 3–4 centimeters of dilation, when contractions become more frequent, stronger, and more regular. The transition phase, the most intense part of labor, typically occurs at 8–10 centimeters of dilation. Full dilation of 10 centimeters indicates the cervix is completely open and pushing (second stage) can begin. However, the relationship between dilation and labor progression is not perfectly linear. Some people progress quickly through early dilation with mild contractions, while others experience painful contractions before significant dilation occurs. Healthcare providers assess labor readiness by evaluating the whole clinical picture—including contraction strength and frequency, cervical consistency and effacement (thinning), and fetal position—not dilation alone. Additionally, false labor (Braxton-Hicks contractions) can cause dilation without active labor beginning. If you're experiencing contractions or think you might be in labor, contact your healthcare provider for guidance rather than relying on dilation measurements alone.