The latent phase (latent labor) begins when the mother feels regular
uterine contractions accompanied by slow cervical dilation.
In the past the active phase (active labor) has been defined as beginning when the cervix is dilated to
3 to 4 cm in the presence of uterine contractions. However, data from the
Consortium on Safe Labor study suggests that
in a present day population, 6 cm rather than 4 cm of cervical dilation may
be a more appropriate landmark for the start of the active phase [2,3].
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.
First-stage arrest may be diagnosed if there is :
For spontaneous labor:
6 cm or greater dilation with membrane rupture AND
4 hours or more of adequate contractions (e.g., > 200 Montevideo units) OR
6 hours or more if contractions inadequate with no cervical change
For induced labor:
6 cm or greater dilation with membrane rupture or 5 cm or greater without
membrane rupture AND
4 hours or more of adequate contractions (e.g., > 200 Montevideo units) OR
6 hours or more if contractions inadequate with no cervical change [4].
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.
Second-stage arrest may be diagnosed if there has been
"No progress (descent or rotation) for
4 hours or more in nulliparous women with an epidural
3 hours or more in nulliparous women without an epidural
3 hours or more in multiparous women with epidural
2 hours or more in multiparous women without an epidural"[4]
The third stage begins with delivery of the infant and ends with expulsion
of the placenta. The third stage may last up to 30 minutes.
REFERENCES:
1.
Dystocia and augmentation of labor. ACOG Practice Bulletin No. 49. American
College of Obstetricians and Gynecologists. Obstet Gynecol 2003;102:1445–54.
2. Zhang J, Landy HJ, Branch W, et al. Contemporary Patterns of Spontaneous Labor with Normal Neonatal Outcomes. Obstet Gynecol. 2010;116:1281–1287 PMID:21099592
3. Zhang J, et. al., Reassessing the labor curve in nulliparous women.
Am J Obstet Gynecol. 2002 Oct;187(4):824-8.PMID:12388957
4.
Spong CY, et. al. Preventing the first cesarean delivery: summary of a joint
Eunice Kennedy Shriver National Institute of Child Health and Human Development,
Society for Maternal-Fetal Medicine, and American College of Obstetricians and
Gynecologists Workshop. Obstet Gynecol. 2012 Nov;120(5):1181-93. doi
http://10.1097/AOG.0b013e3182704880. PMID: 23090537
