The third stage of labor commences immediately after the birth of the baby and concludes with the complete delivery of the placenta and fetal membranes. While often brief, recognizing its progression and the signs of placental separation is crucial for appropriate management and the prevention of complications like postpartum hemorrhage.

Key Event: Placental Separation

The primary physiological event during the third stage is the separation of the placenta from the uterine wall. As the uterus strongly contracts and retracts (shrinks down) after the baby’s birth, the surface area of the placental attachment site diminishes. Since the placenta is relatively inelastic, this shearing force causes it to detach from the decidua basalis layer of the uterine wall.

Clinical Signs Indicating Placental Separation:

These signs suggest that the placenta has detached from the uterine wall and is ready to be expelled. Healthcare providers look for these indicators:

1. A Sudden Gush or Trickle of Dark Blood from the Vagina:

   • As the placenta separates, blood that was trapped between the placenta and the uterine wall is released.

   • The amount is usually not excessive if separation is normal.

   • This is often one of the first noticeable signs.

2. Lengthening of the Visible Portion of the Umbilical Cord:

   • As the placenta detaches and descends into the lower uterine segment or vagina, the portion of the umbilical cord protruding from the vagina will appear to get longer.

   • This is a reliable sign of placental descent.

3. Change in Uterine Shape and Position:

   • Becomes Firmer and More Globular (Rounded): After the bulky placenta has moved out of the main body of the uterus, the uterus contracts more effectively, becoming firmer and more rounded (globular) in shape when palpated abdominally.

   • Rises in the Abdomen: As the detached placenta moves into the lower uterine segment or upper vagina, the now smaller and firmer uterine fundus (top of the uterus) rises in the abdomen. It may be palpated above the umbilicus.

4. The Mother May Experience a Mild Contraction or Urge to Push (Less Consistent Sign):

   • Some women report feeling another mild contraction or an urge to bear down as the placenta descends into the vagina and stimulates pressure receptors.

   • This is not as universally experienced or as reliable as the other signs.

Other Observations During the Third Stage:

• Uterine Contractions Continue: The uterus continues to contract, although these contractions may be less intense than those experienced during the second stage. These contractions are vital for placental separation and to constrict blood vessels at the placental site, preventing excessive bleeding.

• Maternal Shivering: Some women experience shivering or tremors after delivery, which can be a normal physiological response.

Importance of Recognizing These Signs:

• Guidance for Management: These signs inform the healthcare provider when it is appropriate to apply controlled cord traction (if using active management) or when to encourage the mother to push (if using expectant management) for placental expulsion.

• Assessment of Normal Progress: The appearance of these signs within a reasonable timeframe (typically 5-15 minutes, up to 30 minutes with active management) indicates normal progress of the third stage.

• Early Detection of Problems:

  • Absence of signs of separation along with a prolonged third stage may indicate a retained placenta.

  • Excessive bleeding before or without signs of separation could indicate uterine atony or other complications.

It’s important to note that these signs are observed by the healthcare provider. The mother herself may be more focused on her newborn but might be aware of the gush of blood or the lengthening cord if informed. Continuous assessment of maternal vital signs and blood loss is paramount throughout this stage.