threatened abortion

Last edited 09/2023 and last reviewed 09/2023

Threatened abortion is the earliest stage of most spontaneous abortions. There is bleeding from the genital tract, but the cervix is closed and there is no discharge of products of conception.

Vaginal micronized progesterone in threatened miscarriage:

• the effects of first-trimester use of vaginal micronized progesterone have been evaluated in 2 large, high-quality, multicenter placebo-controlled trials, one targeting women with unexplained recurrent miscarriages (the PROMISE [PROgesterone in recurrent MIScarriagE] trial) and the other targeting women with early pregnancy bleeding (the PRISM [PRogesterone In Spontaneous Miscarriage] trial) (1)

  • a key finding, first observed in the PROMISE trial, and then replicated in the PRISM trial, was that treatment with vaginal micronized progesterone 400 mg twice daily was associated with increasing live birth rates according to the number of previous miscarriages
  • therefore, women with a history of miscarriage who present with bleeding in early pregnancy may benefit from the use of vaginal micronized progesterone 400 mg twice daily

NICE state with respect to threatened miscarriage:

• a woman with a confirmed intrauterine pregnancy with a fetal heartbeat who presents with vaginal bleeding, but has no history of previous miscarriage, should be advised that:
  • if her bleeding gets worse, or persists beyond 14 days, she should return for further assessment
  • if the bleeding stops, she should start or continue routine antenatal care
• vaginal micronised progesterone 400 mg twice daily should be offered to women with an intrauterine pregnancy confirmed by a scan, if they have vaginal bleeding and have previously had a miscarriage
• if a fetal heartbeat is confirmed, continue progesterone until 16 completed weeks of pregnancy.

Reference:

• 1) Coomarasamy A, Devall AJ, Brosens JJ, et al. Micronized vaginal progesterone to prevent miscarriage: a critical evaluation of randomized evidence. Am J Obstet Gynecol. 2020;223(2):167-176. doi:10.1016/j.ajog.2019.12.006
• 2) NICE (September 2023).Ectopic pregnancy and miscarriage: diagnosis and initial management