What do systematic reviews say?

Vaginal progesterone vs no treatment or placebo

Vaginal progesterone showed no clear difference in infant birthweight less than 2500 g compared with no treatment or placebo (moderate certainty).

• Prenatal administration of progestogens for preventing spontaneous preterm birth in women with a multiple pregnancy 2019 · Cochrane Headline outcomes only
  RR 0.95 [0.84, 1.07]
  3 studies · 2640 participants
  Moderate

Vaginal progesterone vs no treatment or placebo

Vaginal progesterone showed no clear difference in preterm birth less than 37 weeks compared with no treatment or placebo (moderate certainty).

• Prenatal administration of progestogens for preventing spontaneous preterm birth in women with a multiple pregnancy 2019 · Cochrane Headline outcomes only
  RR 0.97 [0.89, 1.06]
  6 studies · 1597 participants
  Moderate

Vaginal progesterone vs no treatment or placebo

Vaginal progesterone showed no clear difference in preterm birth less than 28 weeks compared with no treatment or placebo (low certainty).

• Prenatal administration of progestogens for preventing spontaneous preterm birth in women with a multiple pregnancy 2019 · Cochrane Headline outcomes only
  RR 1.53 [0.79, 2.97]
  3 studies · 1345 participants
  Low

Vaginal progesterone vs no treatment or placebo

Vaginal progesterone showed no clear difference in perinatal death compared with no treatment or placebo (low certainty).

• Prenatal administration of progestogens for preventing spontaneous preterm birth in women with a multiple pregnancy 2019 · Cochrane Headline outcomes only
  RR 1.23 [0.74, 2.06]
  3 studies · 2287 participants
  Low

Vaginal progesterone vs no treatment or placebo

Vaginal progesterone showed no clear difference in preterm birth less than 34 weeks compared with no treatment or placebo (low certainty).

• Prenatal administration of progestogens for preventing spontaneous preterm birth in women with a multiple pregnancy 2019 · Cochrane Headline outcomes only
  RR 0.9 [0.66, 1.23]
  5 studies · 1503 participants
  Low

Vaginal progesterone vs no treatment or placebo

• Prenatal administration of progestogens for preventing spontaneous preterm birth in women with a multiple pregnancy 2019 · Cochrane Headline outcomes only
  no estimate extracted
  0 studies · 0 participants
  GRADE not reported

Cervical pessary vs vaginal progesterone

Cervical pessary showed no clear difference in maternal infection or inflammation compared with vaginal progesterone (moderate certainty).

• Cervical pessary for preventing preterm birth in singleton pregnancies 2022 · Cochrane Headline outcomes only
  RR 0.95 [0.81, 1.12]
  2 studies · 265 participants
  Moderate

Cervical pessary vs vaginal progesterone

Cervical pessary showed no clear difference in neonatal/paediatric care unit admission compared with vaginal progesterone (low certainty).

• Cervical pessary for preventing preterm birth in singleton pregnancies 2022 · Cochrane Headline outcomes only
  RR 0.98 [0.49, 1.98]
  1 study · 254 participants
  Low

Cervical pessary vs vaginal progesterone

Cervical pessary showed no clear difference in fetal/infant mortality compared with vaginal progesterone (low certainty).

• Cervical pessary for preventing preterm birth in singleton pregnancies 2022 · Cochrane Headline outcomes only
  RR 1.97 [0.5, 7.7]
  2 studies · 265 participants
  Low

Cervical pessary vs vaginal progesterone

• Cervical pessary for preventing preterm birth in singleton pregnancies 2022 · Cochrane Headline outcomes only
  no estimate extracted
  1 study · 11 participants
  Low

Cervical pessary vs vaginal progesterone

The review found no eligible studies for this question.

• Cervical pessary for preventing preterm birth in singleton pregnancies 2022 · Cochrane Headline outcomes only
  no estimate extracted
  Studies not reported
  No studies found

Cervical pessary vs vaginal progesterone

Cervical pessary showed no clear difference in delivery before 34 weeks' gestation compared with vaginal progesterone (moderate certainty).

• Cervical pessary for preventing preterm birth in singleton pregnancies 2022 · Cochrane Headline outcomes only
  RR 0.72 [0.52, 1.02]
  3 studies · 1126 participants
  Moderate

Cervical pessary vs vaginal progesterone

Cervical pessary showed no clear difference in delivery before 37 weeks' gestation compared with vaginal progesterone (moderate certainty).

• Cervical pessary for preventing preterm birth in singleton pregnancies 2022 · Cochrane Headline outcomes only
  RR 0.89 [0.73, 1.09]
  3 studies · 1126 participants
  Moderate