Abstract
Background:
Natural contraception is an affordable and accessible alternative to synthetic hormonal methods. One strategy for controlling overpopulation involves the use of plant-based agents that possess antifertility properties. Carica papaya (papaya) leaves have garnered scientific interest due to their rich content of bioactive compounds. Flavonoids, alkaloids, and saponins present in papaya leaves are known to influence reproductive physiology by modulating hormonal activity, disrupting follicular development, and altering uterine conditions.

Aim:
This study aimed to investigate the antifertility effects of papaya (Carica papaya L.) leaf extract by evaluating its influence on the length of the estrous cycle and the expression of estrogen receptor beta (ER-β) in the ovaries of female white rats (Rattus norvegicus).

Methods:
This study included six female albino rats (Rattus norvegicus) in the treatment group: negative control, P1 (3.15 mg/kgBW), and P2 (4.72 mg/kgBW) groups. Vaginal swab and Giemsa-stained epithelial histopathology were used to determine the estrous cycle duration. Immunohistochemistry was utilized to observe ovarian ER-β receptors.

Results:
The P2 dosage group demonstrated a 3-day increase in estrus cycle length and a 56.97% decrease in ovarian ER-β expression. This shows that the group can prolong the estrous cycle with a diestrus phase predominance and diminish ovarian ER-β expression, making it an anti-infertility drug.

Conclusion:
The P2 group best prolongs the estrous cycle of female white rats. The expression of ovarian ER-β decreases.

Key words: Antifertility, Extract of papaya leaf, ER-β, Vaginal Swab