The latent phase (latent labor) begins when the mother feels regular uterine contractions accompanied by
slow cervical dilation. Latent labor may last up to 20 hours in women who have never given birth to a child, and 14 hours in women who have given birth to a child in
the past. Latent labor ends when the cervix is about 3 to 4 centimeters.
The active phase (active labor) begins when the cervix is dilated to 3
to 4 cm in the presence of uterine contractions. During the active phase
uterine contractions become more frequent, the cervix dilates more quickly,
and the baby descends into the pelvis.
As the mother transitions from the end of the first stage of
labor to the beginning of the second stage of labor her contractions may become
more frequent and intense. During transition the mother may experience shaking,
shivering, nausea, and vomiting. The active phase ends when the cervix has
completely dilated to 10 centimeters.
The Second Stage
The second stage of pregnancy begins when the cervix is fully dilated.
The mother will usually feel a strong pressure in her rectum and an urge to push.
As the infant's scalp becomes visible the mother will also feel burning and
stinging. Loss of bowel or bladder control during the second stage is common. The second
stage ends with delivery of the infant.
The second stage usually lasts up to 2 hours in nulliparous women and 1 hour
in multiparous women. The "normal" second stage may last up to one hour longer
in women who have received regional anesthesia (an epidural).