RCOG Definition of Recurrent Pregnancy Loss
The Royal College of Obstetricians and Gynaecologists (RCOG) defines recurrent pregnancy loss as the loss of three or more consecutive pregnancies before 24 weeks of gestation. 1
Key Diagnostic Criteria
The RCOG definition requires specific elements to establish the diagnosis:
- Three or more consecutive pregnancy losses occurring before 24 weeks of gestation 1
- Clinically recognized pregnancies only (confirmed by ultrasound or hCG testing) 1
- Anembryonic pregnancies (blighted ova) are included in the count, as they represent confirmed early pregnancy losses that meet diagnostic criteria 1, 2
Important Clinical Context
Comparison with Other International Guidelines
The RCOG definition differs from other major international societies, creating some clinical confusion:
- RCOG requires three consecutive losses before initiating formal evaluation 1, 3
- The American Society for Reproductive Medicine (ASRM) and European Society of Human Reproduction and Embryology (ESHRE) define recurrent pregnancy loss as two or more losses, representing a lower threshold for investigation 3, 4
- This definitional inconsistency affects the reported incidence, which ranges from 1% to 5% depending on which criteria are applied 5
Clinical Implications of the Three-Loss Threshold
The RCOG's requirement for three losses before formal evaluation may delay diagnosis and treatment for some couples. 4 Research demonstrates that nulliparous women with two consecutive first-trimester miscarriages who receive supportive care achieve excellent outcomes, with 72.7% achieving live birth in subsequent pregnancies 4. This evidence suggests that earlier intervention after two losses may be beneficial, particularly for women without living children.
What Counts as a Loss
The RCOG definition specifically includes:
- Anembryonic pregnancies (gestational sac ≥25 mm without an embryo, or absence of embryo on serial examinations) 2
- These must be intrauterine pregnancies confirmed by ultrasound or hCG 1
- The pregnancy must be clinically recognized, not biochemical pregnancies alone 2
Common Pitfall
Do not exclude anembryonic pregnancies from your count when determining if a patient meets RCOG criteria for recurrent pregnancy loss. These represent confirmed conceptions with failed development and are explicitly included in the definition 1, 2. Anembryonic pregnancies frequently result from chromosomal errors (50-60% of early losses), the same mechanism as other early pregnancy losses 2.