Definition of Habitual Abortion (Recurrent Pregnancy Loss)
Habitual abortion, now termed recurrent pregnancy loss (RPL), is defined as two or more consecutive clinically recognized first-trimester pregnancy losses, and evaluation should be initiated after the second loss. 1
Historical vs. Current Definition
The terminology and diagnostic threshold have evolved significantly:
Historical definition: Three or more consecutive spontaneous pregnancy losses before 20 weeks of gestation was the traditional criterion used through the 1990s and early 2000s 2, 3, 4
Current definition: The threshold has been lowered to two or more consecutive clinically recognized first-trimester losses based on contemporary guidelines, recognizing that the risk of subsequent loss increases substantially after just two losses 1, 5
Epidemiology: Approximately 2–5% of reproductive-aged couples experience RPL, representing a significant reproductive health burden 1
What Counts as a Loss
Include anembryonic pregnancies (blighted ovum) when calculating recurrent pregnancy losses for workup purposes, as they represent confirmed early pregnancy losses meeting diagnostic criteria 5
Clinically recognized pregnancies are those confirmed by ultrasound or histopathology, not just positive pregnancy tests 1
When to Initiate Evaluation
Begin comprehensive evaluation after the second consecutive loss rather than waiting for a third loss, as this approach allows earlier identification of treatable causes and improves outcomes 1, 5
The rationale for this change includes:
Psychological burden: Waiting for a third loss causes unnecessary emotional distress when treatable conditions may be present 6
Treatable causes exist: Antiphospholipid syndrome, chromosomal rearrangements, and anatomical abnormalities can be identified and managed after two losses 1, 7
Risk stratification: After two consecutive losses, the risk of a third loss increases substantially compared to the general population 3
Long-Term Health Implications
Women with a history of recurrent pregnancy loss face significant long-term cardiovascular risks:
45% higher odds of developing ischemic heart disease later in life (OR 1.45,95% CI 1.18–1.78) 1
Prior stillbirth is associated with increased risk of non-fatal cardiovascular disease (OR 1.49,95% CI 1.08–2.06) and fatal cardiovascular events (OR 2.23,95% CI 1.90–2.62) 1
Critical Distinction from Other Pregnancy Complications
Cervical incompetence primarily causes second-trimester losses and does not contribute to early first-trimester recurrent loss 7
Previable and periviable PPROM (preterm prelabor rupture of membranes before 23–26 weeks) is a distinct entity from recurrent first-trimester loss and requires different management 8
Common Pitfall to Avoid
Do not delay evaluation until three losses have occurred. The outdated three-loss threshold postpones diagnosis of treatable conditions like antiphospholipid syndrome, which has Grade 1A evidence for treatment efficacy and directly impacts maternal-fetal morbidity and mortality 1, 5, 7