What do systematic reviews say?

Intramuscular (IM) progesterone vs no treatment or placebo

Intramuscular (IM) 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 0.99 [0.9, 1.08]
  5 studies · 4071 participants
  Moderate

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

• 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

A dose of vitamin D 601 IU or higher vs 600 IU or lower alone or with other nutrients

A dose of vitamin D 601 IU or higher probably leads to lower gestational diabetes compared with 600 IU or lower alone or with other nutrients (moderate certainty).

• Regimens of vitamin D supplementation for women during pregnancy 2019 · Cochrane Headline outcomes only
  RR 0.54 [0.34, 0.86]
  5 studies · 1846 participants
  Moderate

A dose of vitamin D 601 IU or higher vs 600 IU or lower alone or with other nutrients

It is very uncertain whether A dose of vitamin D 601 IU or higher changes low birthweight compared with 600 IU or lower alone or with other nutrients (very low certainty).

• Regimens of vitamin D supplementation for women during pregnancy 2019 · Cochrane Headline outcomes only
  RR 0.9 [0.66, 1.24]
  4 studies · 1550 participants
  Very low

A dose of vitamin D 4000 IU/d or more vs 3999 IU/d or less alone or with any other nutrient

A dose of vitamin D 4000 IU/d or more showed no clear difference in gestational diabetes compared with 3999 IU/d or less alone or with any other nutrient (low certainty).

• Regimens of vitamin D supplementation for women during pregnancy 2019 · Cochrane Headline outcomes only
  RR 0.89 [0.56, 1.42]
  5 studies · 2276 participants
  Low

A dose of vitamin D 4000 IU/d or more vs 3999 IU/d or less alone or with any other nutrient

A dose of vitamin D 4000 IU/d or more showed no clear difference in low birthweight compared with 3999 IU/d or less alone or with any other nutrient (low certainty).

• Regimens of vitamin D supplementation for women during pregnancy 2019 · Cochrane Headline outcomes only
  RR 0.92 [0.49, 1.7]
  2 studies · 1099 participants
  Low

Intervention not reported

The intervention leads to higher HELLP syndrome (high certainty).

• Calcium supplementation during pregnancy for preventing hypertensive disorders and related problems 2018 · Cochrane Headline outcomes only
  RR 2.67 [1.05, 6.82]
  2 studies · 12901 participants
  High

Any antihypertensive drug vs no antihypertensive drugs/placebo

The review found no eligible studies for this question.

• Antihypertensive drug therapy for mild to moderate hypertension during pregnancy 2018 · Cochrane Headline outcomes only
  no estimate extracted
  Studies not reported
  No studies found
• Antihypertensive drug therapy for mild to moderate hypertension during pregnancy 2018 · Cochrane Headline outcomes only
  no estimate extracted
  Studies not reported
  No studies found

Any antihypertensive drug vs no antihypertensive drugs/placebo

It is very uncertain whether any antihypertensive drug changes eclampsia compared with no antihypertensive drugs/placebo (very low certainty).

• Antihypertensive drug therapy for mild to moderate hypertension during pregnancy 2018 · Cochrane Headline outcomes only
  RR 0.52 [0.13, 2.06]
  7 studies · 713 participants
  Very low

Any antihypertensive drug vs no antihypertensive drugs/placebo

Any antihypertensive drug showed no clear difference in changed/stopped drugs due to maternal side‐effects compared with no antihypertensive drugs/placebo (low certainty).

• Antihypertensive drug therapy for mild to moderate hypertension during pregnancy 2018 · Cochrane Headline outcomes only
  RR 1.93 [0.92, 4.06]
  16 studies · 1503 participants
  Low

Any antihypertensive drug vs no antihypertensive drugs/placebo

Any antihypertensive drug showed no clear difference in elective delivery (induction of labour + elective caesarean section) compared with no antihypertensive drugs/placebo (moderate certainty).

• Antihypertensive drug therapy for mild to moderate hypertension during pregnancy 2018 · Cochrane Headline outcomes only
  RR 0.93 [0.84, 1.04]
  4 studies · 710 participants
  Moderate

Any antihypertensive drug vs no antihypertensive drugs/placebo

The review found no eligible studies for this question.

• Antihypertensive drug therapy for mild to moderate hypertension during pregnancy 2018 · Cochrane Headline outcomes only
  no estimate extracted
  Studies not reported
  No studies found
• Antihypertensive drug therapy for mild to moderate hypertension during pregnancy 2018 · Cochrane Headline outcomes only
  no estimate extracted
  Studies not reported
  No studies found

Any antihypertensive drug vs no antihypertensive drugs/placebo

Any antihypertensive drug showed no clear difference in admission to neonatal or intensive care nursery compared with no antihypertensive drugs/placebo (low certainty).

• Antihypertensive drug therapy for mild to moderate hypertension during pregnancy 2018 · Cochrane Headline outcomes only
  RR 1.01 [0.83, 1.22]
  10 studies · 1570 participants
  Low

Any antihypertensive drug vs no antihypertensive drugs/placebo

Any antihypertensive drug probably leads to lower severe hypertension compared with no antihypertensive drugs/placebo (moderate certainty).

• Antihypertensive drug therapy for mild to moderate hypertension during pregnancy 2018 · Cochrane Headline outcomes only
  RR 0.49 [0.4, 0.6]
  20 studies · 2558 participants
  Moderate

Any antihypertensive drug vs no antihypertensive drugs/placebo

Any antihypertensive drug showed no clear difference in total reported fetal or neonatal deaths (including miscarriage) compared with no antihypertensive drugs/placebo (moderate certainty).

• Antihypertensive drug therapy for mild to moderate hypertension during pregnancy 2018 · Cochrane Headline outcomes only
  RR 0.72 [0.5, 1.04]
  29 studies · 3365 participants
  Moderate

Any antihypertensive drug vs no antihypertensive drugs/placebo

Any antihypertensive drug showed no clear difference in small‐for‐gestational age compared with no antihypertensive drugs/placebo (moderate certainty).

• Antihypertensive drug therapy for mild to moderate hypertension during pregnancy 2018 · Cochrane Headline outcomes only
  RR 0.96 [0.78, 1.18]
  21 studies · 2686 participants
  Moderate

Any antihypertensive drug vs no antihypertensive drugs/placebo

It is very uncertain whether any antihypertensive drug changes maternal death compared with no antihypertensive drugs/placebo (very low certainty).

• Antihypertensive drug therapy for mild to moderate hypertension during pregnancy 2018 · Cochrane Headline outcomes only
  RR 1.11 [0.18, 7.02]
  5 studies · 525 participants
  Very low

Interventionist care vs expectant care

• Interventionist versus expectant care for severe pre‐eclampsia between 24 and 34 weeks' gestation 2018 · Cochrane Headline outcomes only
  no estimate extracted
  2 studies · 320 participants
  Low

Interventionist care vs expectant care

It is very uncertain whether interventionist care changes eclampsia compared with expectant (delayed delivery) care (very low certainty).

• Interventionist versus expectant care for severe pre‐eclampsia between 24 and 34 weeks' gestation 2018 · Cochrane Headline outcomes only
  RR 0.98 [0.06, 15.58]
  2 studies · 359 participants
  Very low