Progesterone after mifepristone: A pilot prospective single arm clinical trial for women who have changed their mind after commencing medical abortion

Aim: This pilot study aimed to assess the utility of an oral progesterone treatment protocol for women who commenced medical abortion and then changed their mind and wished instead to maintain their pregnancy.

Methods: The Progesterone-After-Mifepristone—pilot for efficacy and reproducibility (PAMper) trial was designed as a prospective single-arm pilot clinical trial, conducted via telehealth. Women aged 18 to 45 years in Australia who reported ingesting mifepristone within the last 72 h to initiate medical abortion and had not taken misoprostol were included. Initial contact was by a web-based form. Following informed consent, participants were prescribed oral progesterone to be taken 400 mg twice per day for 3 days then 400 mg at night until completion of a 19 day course. Pregnancy viability was assessed by ultrasound scan after 14 days of progesterone treatment.

Results: Between October 2020 and June 2021, nine women contacted the PAMper trial, of whom six enrolled and commenced progesterone treatment. These women reported ingesting mifepristone at 40–70 days of gestation, with progesterone being commenced within 5.7–72 h of mifepristone ingestion. Five participants had ongoing, live pregnancies at the primary endpoint (ultrasound at >2 weeks). One participant had a miscarriage after 9 days of progesterone treatment. There were no clinically significant adverse events.

Conclusion: This small study demonstrated a clinically sound protocol for research-ing the use of progesterone-after-mifepristone for women in this circumstance. Results of this pilot study support the need for further larger scale trials in this field.