The role of short luteal phases on cycle regularity during the perimenopausal transition.

Objective: The aim of the study was to explore the correlation between short luteal phases and cycle irregularity in perimenopausal women.

Methods: In this feasibility pilot study, daily salivary-progesterone measurements from presumed perimenopausal women have been analyzed using the inne minilab-an at-home system for ovulation and cycle tracking. Data were collected between 2020 to August 2022 from 29 women from Germany and Austria from users over the age of 42 years. Mean age was 44.5 years. The women were divided into two groups based on the presence of short luteal phases. Wilcoxon rank sum test was used to compare the two groups with regard to perimenopausal characteristics: cycle length variability, occurrence, and frequency of short cycles, long cycles, and anovulatory cycles.

Results: A significant correlation (P value =0.02) was found between short luteal phases and short cycle length under 23 days, with a median of two short cycles in the short luteal phase positive group compared to a median of 0 short cycles in the negative group. However, this correlation did not persist when adjusting for number of observations per participant. No difference was found when comparing other cycle characteristics.

Conclusions: These findings could suggest that it may not be feasible to utilize the occurrence of short luteal phases in the context of expressing the likelihood of cycle irregularity, length, or anovulation. However, because of the small sample size in this study, the null findings could be due to lack of power. Larger studies would be needed to determine how short luteal phases may be correlated to cycle regularity.