Do Miscarriages Need to Be Consecutive for APS Diagnosis?
No, miscarriages do NOT need to be consecutive to meet the clinical criteria for antiphospholipid syndrome (APS). The diagnostic criteria specify "three consecutive spontaneous miscarriages before 10 weeks of gestation" as ONE pathway to diagnosis, but this is not the only obstetric criterion, and the term "consecutive" applies specifically to this early pregnancy loss category 1.
Understanding the Obstetric Criteria for APS
The obstetric manifestations that qualify for APS diagnosis include 1, 2:
- Three or more consecutive spontaneous miscarriages before 10 weeks gestation (where other causes have been excluded)
- One or more unexplained fetal deaths after 10 weeks gestation (does not require consecutive losses)
- One or more premature births before 34 weeks due to severe pre-eclampsia, eclampsia, or placental insufficiency (does not require consecutive events)
Key Clinical Distinctions
The "consecutive" requirement only applies to early miscarriages (before 10 weeks). For later pregnancy losses or complications, even a single event can meet diagnostic criteria if accompanied by positive antiphospholipid antibodies 1, 3.
Important Caveats:
Laboratory confirmation is mandatory: Positive antiphospholipid antibodies (lupus anticoagulant, anticardiolipin antibodies, or anti-β2-glycoprotein I antibodies) must be confirmed at least 12 weeks apart to avoid transient positivity 4
Triple positivity indicates highest risk: Patients positive for all three antibody types (LAC + aCL + aβ2GPI of same isotype) show the strongest association with obstetric APS and have the highest risk of recurrent pregnancy complications 5, 4
Non-consecutive losses may still warrant evaluation: Even if losses are not consecutive, patients with multiple miscarriages and positive antiphospholipid antibodies may represent "non-standard OAPS" and could benefit from treatment, though they may not meet strict classification criteria 3
Clinical Pitfall to Avoid
Do not dismiss patients who have had pregnancy losses interspersed with successful pregnancies. While they may not meet the strict "three consecutive" criterion for early losses, they could still qualify through other obstetric criteria (late fetal death, severe pre-eclampsia) or may develop APS over time. Consider testing for antiphospholipid antibodies in any patient with recurrent pregnancy morbidity, as pregnancy itself can trigger or unmask APS 6.