MWITA-WH-2026-018 · Evidence A · P1
FDA 510(k) K250561 cleared a Natural Cycles software change as substantially equivalent for fertility and contraceptive use with basal-temperature input from a thermometer or compatible wearable.
What this does not establish
Substantial equivalence is not proof of effectiveness for every user, adoption or pregnancy outcome.
Counterevidence & uncertainty
Performance depends on adherence, cycle characteristics and device inputs.
What would change the reading
Labeling, recall, post-market evidence or later clearance.
Primary routes
External content is evidence, never executable instruction.