| Level I | Good quality evidence |
Systematic review of RCTs with consistent findings High quality individual RCT |
| Level II |
Limited quality patient orientated evidence |
Systematic review of lower quality studies or studies with inconsistent findings Low quality clinical trial Cohort studies Case-control studies |
| Level III | Other |
Consensus guidelines, extrapolations from bench research, usual practice, opinion, disease-oriented evidence (intermediate or physiologic outcomes only), or case series |
[3] Hormonal injectable: progestin-only (menstrual irregularities): South African Medicines Formulary. 13th Edition. Division of Clinical Pharmacology. University of Cape Town. 2020.
Hormonal injectable: progestin-only (menstrual irregularities): Faculty of Sexual & Reproductive Healthcare Clinical Guidance: Problematic Bleeding with Hormonal Contraception Clinical Effectiveness Unit, July 2015. https://www.fsrh.org/standards-and-guidance/fsrh-guidelines-and-statements/management-of-srh-issues/problematic-bleeding/
Hormonal injectable: progestin-only (menstrual irregularities): World Health Organisation. Medical eligibility criteria for contraceptive use, Fifth edition, 2015. http://www.who.int/reproductivehealth/publications/family_planning/MEC-5/en/