Smarter Decisions,
Better Care
UpToDate synthesizes the most recent medical information into evidence-based practical recommendations clinicians trust to make the right point of care decisions.
For more information, click below.
Subscribers log in here
Related articles
| AuthorsFrank Silverman, MDEran Bornstein, MD | Section EditorCharles J Lockwood, MD | Deputy EditorVanessa A Barss, MD |
Topic Outline
INTRODUCTION
The third stage of labor refers to the interval from the delivery of the baby to the separation and expulsion of the placenta. The major complication associated with this period is postpartum hemorrhage (PPH), which is the most common cause of maternal morbidity and mortality in developing countries. Even in developed countries, although maternal mortality rates are much lower, PPH remains a major concern [1]. It ranks just behind thromboembolic events and hypertensive disease as a common cause of maternal death in women whose pregnancies continue beyond 20 weeks.
Some clinicians also recognize a fourth stage of labor, which begins at the delivery of the placenta and lasts for an arbitrary period of time afterward. This very early postpartum period is associated with maternal complications from hemorrhage, fluid shifts, and embolism.
THIRD STAGE PHYSIOLOGY
Normal placental separation — Placental separation occurs due to shearing of the placental surface when the uterus contracts after the infant is delivered. Signs of placental separation include a gush of blood, lengthening of the umbilical cord, and anterior-cephalad movement of the uterine fundus, which becomes firmer and globular after the placenta detaches. Placental expulsion follows as a result of a combination of events including spontaneous uterine contractions, downward pressure from the developing retroplacental hematoma, and an increase in maternal intraabdominal pressure. (See "Overview of postpartum care", section on 'Uterine involution'.)
The changes in the uteroplacental unit during placental separation have been classified as [2]:
Subscribers log in here