The Science BehindYour Cycle Recommendations
Every recommendation in HerRhythm is carefully sourced from peer-reviewed research. Explore the complete evidence base for both regular menstrual cycles and PCOS, with direct links to all studies and transparent quality ratings.
Our Evidence Standards
Every recommendation is backed by peer-reviewed research. Here's what we look for.
Peer-Reviewed
Published in reputable scientific journals with rigorous review processes
Women-Specific
Studies with separate data for women or female-only participants
Systematic Reviews
Meta-analyses and systematic reviews when available for strongest evidence
Evidence Quality Ratings
Multiple systematic reviews or high-quality RCTs
Some limitations or high risk of bias
Preliminary or conflicting findings
Regular Cycle Phase Evidence
Below you'll find hyperlinked studies we've used to inform the recommendations you get. We want to share these with you to be as transparent as possible and for you to make your own mind up based on the evidence.
We're not trying to sell you anything - just making women's health information more accessible and understandable. We know the evidence is changing and has limitations. Much of it still doesn't isolate women's experiences, has small sample sizes, or focuses mainly on younger, healthier women with regular cycles. But this is starting to change, and we're committed to staying current with the latest research.
Click on any phase to explore the evidence.
Continuous Evidence Review
Last updated: January 2026 | Next review: April 2026
We review new menstrual cycle research quarterly and update recommendations based on the latest science.
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