A prospective, randomized, pharmacodynamic study of quick-starting a desogestrel progestin-only pill following ulipristal acetate for emergency contraception

Abstract

Initiating the use of a DSG progestin-only pill (POP) immediately after UPA reduces the ability of UPA to delay ovulation and thus may decrease its efficacy as EC. If starting a DSG POP after using UPA for EC, and possibly any progestin-only method, consideration should be given to delaying for at least 5 days after UPA intake in order to preserve the ovulation delaying effects of UPA.

FSRH Guideline (January 2019, amended October 2023) Combined Hormonal Contraception

“…Limited evidence from biomedical studies129,130 suggests that effectiveness of oral hormonal contraception is not reduced by concomitant use of UPA-EC. Biomedical studies have demonstrated that starting an EE/LNG COC131 or a desogestrel POP129 soon after UPA 30 mg given for emergency contraception (UPA-EC) reduces the ability of UPA-EC to delay ovulation and could therefore reduce the effectiveness of UPA-EC. The FSRH Guideline recommends that after UPA-EC, commencement of CHC is delayed for 5 days (at least 120 hours) after UPA-EC has been given 95.…”

Quick starting hormonal contraception after using oral emergency contraception: a systematic review

“…Two studies administering UPA were conducted in Edinburgh (UK) by one research team 11 12. Other sites included Stockholm (Sweden), Groningen (Netherlands)11 and Santo Domingo (Dominican Republic) 10. Two of the studies were biomedical studies that recruited healthy volunteers who had not had UPSI 10 11.…”

“…In this study, UPA/placebo administration took place once an ovarian follicle was >13  mm in diameter on a transvaginal ultrasound scan (TVU), which corresponds to the mid-to-late follicular phase of the menstrual cycle 11. Another study administered either UPA or placebo, followed 1  day later by either 20 days of progestogen-only pill (POP) [Cerazette ® containing 75  µg desogestrel (DSG)] or 20 days of a placebo to healthy volunteers 10. The UPA/placebo was administered when the lead ovarian follicular diameter was ≥14  mm, corresponding to the mid-to-late follicular phase of the menstrual cycle 10.…”

“…Another study administered either UPA or placebo, followed 1  day later by either 20 days of progestogen-only pill (POP) [Cerazette ® containing 75  µg desogestrel (DSG)] or 20 days of a placebo to healthy volunteers 10. The UPA/placebo was administered when the lead ovarian follicular diameter was ≥14  mm, corresponding to the mid-to-late follicular phase of the menstrual cycle 10. A partial crossover design was employed with each participant receiving two different treatment combinations with one menstrual cycle in between.…”

“…One RCT used TVU measurements of follicle size and serum estradiol/progesterone levels to calculate Hoogland scores of ovarian activity after UPA administration and COC (Microgynon 30 containing 30  µg EE and 150  µg LNG) use; scores of three or less indicated ovarian quiescence 11. Another study determined if the POP (Cerazette containing 75  µg DSG) had exerted contraceptive effects on cervical mucus after UPA use by calculating a modified World Health Organizaion Cervical Mucus Score; scores of four or less indicated that mucus had become impenetrable to sperm 10. This study also gathered TVU measurements of follicle size, plasma etonogestrel levels (the active metabolite of desogestrel) and serum estradiol/progesterone levels.…”