What they did:

Researchers followed 129 healthy women between ages 40 and 56, all in different stages of perimenopause (classified using the STRAW criteria). Over the course of four weeks, participants provided saliva samples every fourth day. These were analyzed for estradiol (E2) and progesterone (P4). At the same time, the women completed detailed questionnaires about resilience, well-being, stress, and mood changes.

What they found:

• Progesterone (P4): Women with higher average progesterone levels consistently showed greater resilience in the study — meaning they reported coping better with stress and described better overall mental well-being. The study also noted associations with lower perceived stress, fewer low-mood experiences, and higher life satisfaction. Notably, this pattern held across different perimenopause stages.
• Estradiol (E2): In contrast, estradiol did not show a reliable association with resilience, stress, or well-being in this study.

Why this matters:

These findings suggest that during perimenopause, progesterone — not estradiol — may act as a biological marker of resilience. In other words, women in the study with higher progesterone patterns appeared more buffered against stress and mood disruption, while estradiol levels alone didn't predict how resilient they felt.

Takeaway:

This challenges the common assumption that estradiol is the dominant hormone influencing emotional well-being in midlife. Instead, the study highlights a potential connection between progesterone and mood, stress experience, and quality of life in the perimenopause years — adding to a growing body of research worth knowing about.

The Swiss Perimenopause Study – study protocol of a longitudinal prospective study in perimenopausal women