NCT03930212.

Study name	Progesterone supplementation in threatened abortion (Prothreat)
Methods	2‐arm placebo‐controlled randomised trial.
Participants	Women presenting with threatened abortion diagnosed by history and ultrasound examination, a singleton viable fetus with gestational age < 20 weeks and a closed normal length cervix. Exclusion criteria include short cervix < 2 cm; multiple pregnancy; dead fetus; open cervix ≥ 2 cm; history of cervical surgery.
Interventions	400 mg rectal progesterone suppositories once daily versus placebo
Outcomes	Relief of pain; completion of pregnancy beyond 20 weeks; stoppage of bleeding; abortion less than 20 weeks
Starting date	01‐Jan‐2018
Contact information	ayman.dawood@med.tanta.edu.eg
Notes

DM: diabetes mellitus;hCG: Human chorionic gonadotropin;NSAIDs: non steroidal anti‐inflammatory drugs.