First Stage

How contractions change and intensify across stages

How contractions change and intensify across stages

Contractions as a physiologic signal A uterine contraction is a coordinated tightening and relaxation of myometrial muscle fibers. In late pregnancy, the uterus becomes increasingly responsive to hormonal and mechanical signals, including oxytocin activity, prostaglandins, cervical stretching, and fetal pressure. Not every contraction means labor has begun. Braxton Hicks or prodromal contractions can be uncomfortable […]

Why dilation speeds up in active labor

Why dilation speeds up in active labor

Active labor is a physiologic turning point The first stage of labor is the period in which the cervix dilates from closed or minimally open to fully dilated, typically described as 10 centimeters. It is commonly divided into latent or early labor, active labor, and the transition phase. The exact boundary between early and active […]

Effacement and full dilation explained

Effacement and full dilation explained

What effacement means Effacement is the thinning, softening, and shortening of the cervix as it prepares for birth. In late pregnancy, the cervix is usually relatively firm, long, and closed. As labor physiology begins, the cervix remodels: collagen fibers loosen, tissue water content changes, inflammatory mediators increase locally, and the lower uterine segment gradually draws […]

Cervix changes and dilation from 0 to 10 cm

Cervix changes and dilation from 0 to 10 cm

What cervical dilation measures Cervical dilation is the estimated diameter of the cervical opening, measured in centimeters during a vaginal examination. At 0 cm, the cervix is closed. At 10 cm, it is considered completely dilated, meaning the cervix no longer forms a significant barrier between the uterus and the vagina. This complete dilation marks […]

Difference between early active and transition labor

Difference between early active and transition labor

The first stage of labor: one continuum with three recognizable phases The first stage of labor begins when true labor contractions cause progressive cervical change and ends when the cervix is fully dilated, usually described as 10 cm. Within this stage, clinicians and birth educators often describe early labor, active labor, and transition labor. These […]

Early active and transition phases explained

Early active and transition phases explained

The first stage of labor: the shared framework The early, active, and transition phases are subdivisions of the first stage of labor. This stage begins when labor contractions create progressive cervical change and ends when the cervix is fully dilated to 10 centimeters. Cervical dilation describes the opening of the cervix, while cervical effacement describes […]

First stage of labor explained

First stage of labor explained

What the first stage of labor means Clinically, the first stage of labor starts when labor contractions become regular enough to cause progressive cervical change. That change includes both softening and thinning of the cervix, known as cervical effacement, and opening of the cervical os, known as dilation. The stage ends only when the cervix […]