Transfer of Vaginal Progesterone to Sexual Partners
There is no clinically significant transfer of vaginal progesterone to sexual partners during intercourse, and no restrictions on sexual activity are needed for women using this medication. 1
Safety for Sexual Partners
The available evidence does not identify partner exposure as a clinical concern with vaginal progesterone therapy:
Sexual activity is generally not restricted in women using vaginal progesterone for any indication (short cervix, preterm birth prevention, or hormone replacement therapy), unless other obstetric contraindications exist. 1
The medication's efficacy is not compromised by intercourse when used as directed, indicating that the drug remains localized to the vaginal and uterine tissues through the first-pass effect rather than being available for transfer. 1, 2
No sexual activity restrictions apply for postmenopausal women using vaginal progesterone for endometrial protection with estrogen therapy. 1
Mechanism Explaining Minimal Transfer Risk
The pharmacokinetics of vaginal progesterone explain why partner transfer is not a concern:
Vaginal progesterone exhibits a unique "first-pass effect" whereby the medication is preferentially absorbed directly from the vagina to the uterus through local transport, resulting in high uterine tissue concentrations but low systemic blood levels. 2, 3
This direct vagina-to-uterus transport mechanism means that progesterone concentrations remain subphysiologic in the bloodstream despite achieving therapeutic levels in target tissues. 3
The bioadhesive gel formulations provide controlled and sustained-release properties that keep the medication localized to vaginal tissues rather than available for external transfer. 3
Important Contraceptive Caveat
While partner transfer is not a concern, there is a critical safety consideration:
Vaginal progesterone does not provide contraceptive protection and should not be relied upon to prevent pregnancy. 1
Women of reproductive age using vaginal progesterone who wish to avoid pregnancy must use additional contraceptive methods such as condoms. 1
The presence of progesterone therapy does not eliminate the need for barrier protection against sexually transmitted diseases. 1
Clinical Bottom Line
Counsel patients that vaginal progesterone poses no risk to sexual partners through transfer during intercourse, but emphasize that barrier methods are still necessary if contraception or STI protection is desired, as the medication provides neither of these protections. 1