Table 1.

Minimum and optimal recommendations for use of sex and gender in human studies

Minimum	Optimal
Study design, data collection, and data analysis
• Include women and men in all human trials unless strong scientific justification. • Include gender nonconforming people as much as possible. • May not need to increase sample size. • Report sex-specific or sex-dependent effect sizes when possible. • Include sex and gender as covariate(s) when possible. • Identify gender of all participants and participant-reported sex at birth. • Document details of menstrual cycle- natural vs. hormonal contraceptive (with type, dose, and duration of use). • If possible, estimate and record participant menstrual cycle day. • Collect menopausal status.	Minimum, plus: • Detail menstrual cycle history. • Use ovulation kits to characterize cycle phase. • Sufficiently power study for covariate(s) or split analysis. • Explore equivalence and interaction testing (moderation analysis). • Report dose and type of estrogen and dose and type of progestin for oral contraceptives. • Stratify participants based on hormonal contraception type/dose or include only participants on same type/dose. • Control for menstrual cycle phase if appropriate. • Perform longer-term tracking of phase durations by urine, blood, or plasma markers. • Control for age, time of day (circadian rhythm), exogenous reproductive hormone use, other medication. • Measure estradiol, luteinizing hormone, follicle stimulating hormone, estrone, progestins, SHBG, and androgens.
Reporting
• Report individual male/female data in tables and figures as separate symbols. • Include information regarding biological sex (at birth) and gender identification. • Report hormone contraception use and type. • Report a priori power analysis results if primary focus is on sex differences. • Include data availability statement. • Use The Stages of Reproductive Aging Workshop (STRAW + 10) criteria to characterize menopausal status and reproductive age.	Minimum, plus: • Document self-reported menstrual/oral contraceptive pill phase at time of testing and cycle history when possible. • Report sex hormone concentrations (absolute/relative levels and relevant ratios). • Report individual regularity of natural menstrual cycle status. • Report duration of contraceptive use. • Identify duration of hormone therapy. • Report pregnancies and births. • Report effect sizes for sex comparisons (e.g., Cohen’s d, correlations, and odds ratios). • Explore potential confounding variables through sensitivity analyses (e.g., body composition).
Data interpretation
• Distinguish statistical vs. clinical/physiological differences. • Include limitations (e.g., confounding factors, sample size). • Keep focus within the context of your sample set.	Minimum, plus: • Include interpretation of data based on menstrual cycle/phase, contraceptive use, or menopausal status as investigated/ appropriate.