Does a short luteal phase correlate with an increased risk of miscarriage? A cohort study.
Level 3 - non-randomized controlled study
Secondary analysis of prospective cohort tracking data
PubMed 36482355 · doi:10.1186/s12884-022-05195-9
What was done
This secondary cohort study analyzed data from four cohorts of couples using standardized protocols to track female cycle biomarkers. The study included 252 women who conceived with a known pregnancy outcome and had luteal phase length data recorded for up to 3 cycles prior to conception. A short luteal phase was defined as under 10 days (with sensitivity analyses at <11, <9, and <8 days). Modified Poisson regression estimated the adjusted incidence risk ratio (aIRR) of miscarriage prior to 20 weeks gestation, controlling for age, demographics, smoking, alcohol use, and prior pregnancy history.
What was found
The overall miscarriage rate was 18.7% (47/252). Having at least one short luteal phase (<10 days) prior to conception was not associated with miscarriage risk compared to having none (aIRR 1.01, 95% CI: 0.57 to 1.80). Alternative threshold definitions (<11, <9, and <8 days) also showed null associations. Women with short luteal phases (<10 days) across all 3 cycles before conception had an aIRR of 2.14, but confidence intervals were wide and crossed unity (95% CI: 0.70 to 6.55).
Why it matters
Clinicians often hypothesize that short luteal phases reflect progesterone deficiency leading to early pregnancy loss. These findings suggest that an isolated preconception short luteal phase does not independently increase clinical miscarriage risk.
Limits
The sample size was modest (n = 252), leaving the study underpowered to detect smaller effects or definitively evaluate recurrent short luteal phases (wide 95% CI: 0.70–6.55). Serum progesterone and human chorionic gonadotropin levels were not directly measured, and cycle tracking relied on user-recorded biomarker methods.
Cited by
- supports The clinical definition of a short luteal phase is a luteal phase lasting fewer than 11 days.