Duration of Postpartum Bleeding
Women can experience normal postpartum bleeding (lochia) for up to 6 weeks after delivery, with the heaviest bleeding occurring in the first 24 hours and gradually decreasing over time. 1
Normal Postpartum Bleeding Timeline
The American College of Radiology defines the normal postpartum bleeding period as lasting between 24 hours and 6 weeks after delivery, following a predictable pattern 1:
- First 24 hours: Heaviest bleeding period with bright red blood 1
- First few days: Blood clots are normal; bleeding remains bright red 1
- Subsequent weeks: Bleeding gradually changes to brownish or yellowish discharge 1
- Volume pattern: Progressively decreases over the entire 6-week period 1
During this 6-week timeframe, the uterus undergoes involution (returns to pre-pregnancy size), and the endometrial cavity may normally contain debris and sometimes gas in 20-25% of women 1. A thickened endometrial echo complex up to 2-2.5 cm is considered normal during this period 1.
When Bleeding Becomes Abnormal
Primary Postpartum Hemorrhage
Excessive bleeding within the first 24 hours after delivery requires immediate medical attention 1, 2. This is defined as cumulative blood loss ≥1,000 mL or bleeding accompanied by signs of hypovolemia 3.
Secondary Postpartum Hemorrhage
Occurs between 24 hours and 6 weeks postpartum 1. Common causes include:
- Retained products of conception 1, 4
- Endometritis (most common cause, accounting for 64% of cases) 4
- Subinvolution of the placental bed 1
- Infection 1
Warning Signs Requiring Evaluation
Bleeding that continues beyond 6 weeks or suddenly increases in volume should be evaluated by a healthcare provider, as it may indicate complications requiring treatment 1.
Risk Factors for Prolonged or Excessive Bleeding
Key risk factors include 1, 5:
- Uterine atony
- Retained placental fragments
- Cesarean delivery
- Large blood loss during delivery (>1 L or requiring blood product replacement) 5
- Postpartum infection
- Emergency cesarean section 5
Important Clinical Considerations
Thrombotic Risk Beyond Bleeding
While postpartum bleeding typically resolves by 6 weeks, the risk of venous thromboembolism remains elevated during this period 6. The highest VTE risk occurs in the first 3 weeks postpartum, with modest elevation persisting through 12 weeks 6, 7.
Common Pitfalls
- Normal postpartum uterine changes (debris, gas, thickened endometrium) should not be confused with pathology 1, 8
- Most blood loss occurs in the first 24 hours, with an average of 135-155 mL in the first 72 hours in normal deliveries 9
- The external cervical os remains slightly more open after vaginal delivery compared to nulliparous women, even after complete involution 8