Estetrol‐based combined oral contraceptives: A systematic review of clinical outcomes

E4-containing COCs could potentially be a safer and more effective alternative to contraceptive use. The findings should be interpreted with caution, as study limitations such as design and confounder bias, small study populations, and short follow-up times characterize the studies included in this review. Further, industry sponsorship bias cannot be ruled out. Further independent research is needed to confirm long-term safety and applicability of E4-containing COCs across diverse populations.