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Administración de suplementos vitamínicos para prevenir abortos espontáneos

Appendices

Appendix 1. Additional searching carried out for the initial version of the review

For the initial version of the review, authors carried out a separate search of CENTRAL (The Cochrane Library, 2003, Issue 2) for the following terms: miscarriage*, spontaneous abortion, recurrent abortion, spontaneous pregnancy loss, recurrent pregnancy loss, fetal death, vitamin*, folate, folic acid; and also MEDLINE (1966 to May 2003), Current Contents (1998 to May 2003) and EMBASE (1980 to May 2003) using the search strategy given below:

  1. miscarriage*

  2. spontaneous abortion

  3. recurrent abortion

  4. habitual abortion

  5. spontaneous pregnancy loss

  6. recurrent pregnancy loss

  7. early pregnancy loss

  8. early pregnancy bleeding

  9. fetal death

  10. #1 or #2 or #3 or #4 or #5 or #6 or #7 or #8 or #9

  11. vitamin*

  12. retinol*

  13. carotenoid*

  14. thiamin*

  15. riboflavin

  16. niacin or nicotinamide or nicotinic acid

  17. pantothenic acid or pantothenate

  18. pyridox*

  19. cyanocobalamin or cobalamin

  20. ascorb*

  21. calciferol

  22. tocopherol* or alpha‐tocopherol

  23. folate*

  24. folic acid

  25. phylloquinone

  26. menaquinone

  27. #13 or #14 or #15 or #16 or #17 or #18 or #19 or #20 or #21 or #22 or #23 or #24 or #25 or #26 or #11 or #12

  28. #10 and #27

  29. random*

  30. controlled‐clinical‐trial

  31. #29 or #30

  32. #28 and #31

'Risk of bias' graph: review authors' judgements about each risk of bias item presented as percentages across all included studies
Figuras y tablas -
Figure 1

'Risk of bias' graph: review authors' judgements about each risk of bias item presented as percentages across all included studies

'Risk of bias' summary: review authors' judgements about each risk of bias item for each included study
Figuras y tablas -
Figure 2

'Risk of bias' summary: review authors' judgements about each risk of bias item for each included study

Funnel plot of comparison: 9 Multivitamin plus iron and folic acid versus iron and folic acid, outcome: 9.1 Total fetal loss.
Figuras y tablas -
Figure 3

Funnel plot of comparison: 9 Multivitamin plus iron and folic acid versus iron and folic acid, outcome: 9.1 Total fetal loss.

Funnel plot of comparison: 9 Multivitamin plus iron and folic acid versus iron and folic acid, outcome: 9.2 Early or late miscarriage.
Figuras y tablas -
Figure 4

Funnel plot of comparison: 9 Multivitamin plus iron and folic acid versus iron and folic acid, outcome: 9.2 Early or late miscarriage.

Funnel plot of comparison: 9 Multivitamin plus iron and folic acid versus iron and folic acid, outcome: 9.3 Stillbirth.
Figuras y tablas -
Figure 5

Funnel plot of comparison: 9 Multivitamin plus iron and folic acid versus iron and folic acid, outcome: 9.3 Stillbirth.

Comparison 1 Vitamin C plus vitamin E versus placebo, Outcome 1 Total fetal loss.
Figuras y tablas -
Analysis 1.1

Comparison 1 Vitamin C plus vitamin E versus placebo, Outcome 1 Total fetal loss.

Comparison 1 Vitamin C plus vitamin E versus placebo, Outcome 2 Early or late miscarriage.
Figuras y tablas -
Analysis 1.2

Comparison 1 Vitamin C plus vitamin E versus placebo, Outcome 2 Early or late miscarriage.

Comparison 1 Vitamin C plus vitamin E versus placebo, Outcome 3 Stillbirth.
Figuras y tablas -
Analysis 1.3

Comparison 1 Vitamin C plus vitamin E versus placebo, Outcome 3 Stillbirth.

Comparison 1 Vitamin C plus vitamin E versus placebo, Outcome 4 Congenital malformations.
Figuras y tablas -
Analysis 1.4

Comparison 1 Vitamin C plus vitamin E versus placebo, Outcome 4 Congenital malformations.

Comparison 1 Vitamin C plus vitamin E versus placebo, Outcome 5 Any adverse effects of vitamin supplementation sufficient to stop supplementation.
Figuras y tablas -
Analysis 1.5

Comparison 1 Vitamin C plus vitamin E versus placebo, Outcome 5 Any adverse effects of vitamin supplementation sufficient to stop supplementation.

Comparison 2 Vitamin C versus no supplement/placebo, Outcome 1 Total fetal loss.
Figuras y tablas -
Analysis 2.1

Comparison 2 Vitamin C versus no supplement/placebo, Outcome 1 Total fetal loss.

Comparison 2 Vitamin C versus no supplement/placebo, Outcome 2 Early or late miscarriage.
Figuras y tablas -
Analysis 2.2

Comparison 2 Vitamin C versus no supplement/placebo, Outcome 2 Early or late miscarriage.

Comparison 2 Vitamin C versus no supplement/placebo, Outcome 3 Stillbirth.
Figuras y tablas -
Analysis 2.3

Comparison 2 Vitamin C versus no supplement/placebo, Outcome 3 Stillbirth.

Comparison 3 Vitamin C plus multivitamins versus placebo plus multivitamins or multivitamins alone, Outcome 1 Total fetal loss.
Figuras y tablas -
Analysis 3.1

Comparison 3 Vitamin C plus multivitamins versus placebo plus multivitamins or multivitamins alone, Outcome 1 Total fetal loss.

Comparison 3 Vitamin C plus multivitamins versus placebo plus multivitamins or multivitamins alone, Outcome 2 Early or late miscarriage.
Figuras y tablas -
Analysis 3.2

Comparison 3 Vitamin C plus multivitamins versus placebo plus multivitamins or multivitamins alone, Outcome 2 Early or late miscarriage.

Comparison 4 Vitamin A plus iron and folate versus iron and folate, Outcome 1 Total fetal loss.
Figuras y tablas -
Analysis 4.1

Comparison 4 Vitamin A plus iron and folate versus iron and folate, Outcome 1 Total fetal loss.

Comparison 4 Vitamin A plus iron and folate versus iron and folate, Outcome 2 Early or late miscarriage.
Figuras y tablas -
Analysis 4.2

Comparison 4 Vitamin A plus iron and folate versus iron and folate, Outcome 2 Early or late miscarriage.

Comparison 4 Vitamin A plus iron and folate versus iron and folate, Outcome 3 Stillbirth.
Figuras y tablas -
Analysis 4.3

Comparison 4 Vitamin A plus iron and folate versus iron and folate, Outcome 3 Stillbirth.

Comparison 5 Vitamin A versus placebo, Outcome 1 Total fetal loss.
Figuras y tablas -
Analysis 5.1

Comparison 5 Vitamin A versus placebo, Outcome 1 Total fetal loss.

Comparison 5 Vitamin A versus placebo, Outcome 2 Early of late miscarriage.
Figuras y tablas -
Analysis 5.2

Comparison 5 Vitamin A versus placebo, Outcome 2 Early of late miscarriage.

Comparison 5 Vitamin A versus placebo, Outcome 3 Stillbirth.
Figuras y tablas -
Analysis 5.3

Comparison 5 Vitamin A versus placebo, Outcome 3 Stillbirth.

Comparison 6 Beta‐carotene versus placebo, Outcome 1 Total fetal loss.
Figuras y tablas -
Analysis 6.1

Comparison 6 Beta‐carotene versus placebo, Outcome 1 Total fetal loss.

Comparison 6 Beta‐carotene versus placebo, Outcome 2 Early or late miscarriage.
Figuras y tablas -
Analysis 6.2

Comparison 6 Beta‐carotene versus placebo, Outcome 2 Early or late miscarriage.

Comparison 6 Beta‐carotene versus placebo, Outcome 3 Stillbirth.
Figuras y tablas -
Analysis 6.3

Comparison 6 Beta‐carotene versus placebo, Outcome 3 Stillbirth.

Comparison 7 Vitamin A or beta‐carotene versus placebo, Outcome 1 Total fetal loss.
Figuras y tablas -
Analysis 7.1

Comparison 7 Vitamin A or beta‐carotene versus placebo, Outcome 1 Total fetal loss.

Comparison 8 Vitamin A (with/without multivitamins) versus multivitamins or placebo, Outcome 1 Total fetal loss.
Figuras y tablas -
Analysis 8.1

Comparison 8 Vitamin A (with/without multivitamins) versus multivitamins or placebo, Outcome 1 Total fetal loss.

Comparison 8 Vitamin A (with/without multivitamins) versus multivitamins or placebo, Outcome 2 Early or late miscarriage.
Figuras y tablas -
Analysis 8.2

Comparison 8 Vitamin A (with/without multivitamins) versus multivitamins or placebo, Outcome 2 Early or late miscarriage.

Comparison 8 Vitamin A (with/without multivitamins) versus multivitamins or placebo, Outcome 3 Stillbirth.
Figuras y tablas -
Analysis 8.3

Comparison 8 Vitamin A (with/without multivitamins) versus multivitamins or placebo, Outcome 3 Stillbirth.

Comparison 9 Multivitamin plus iron and folic acid versus iron and folic acid, Outcome 1 Total fetal loss.
Figuras y tablas -
Analysis 9.1

Comparison 9 Multivitamin plus iron and folic acid versus iron and folic acid, Outcome 1 Total fetal loss.

Comparison 9 Multivitamin plus iron and folic acid versus iron and folic acid, Outcome 2 Early or late miscarriage.
Figuras y tablas -
Analysis 9.2

Comparison 9 Multivitamin plus iron and folic acid versus iron and folic acid, Outcome 2 Early or late miscarriage.

Comparison 9 Multivitamin plus iron and folic acid versus iron and folic acid, Outcome 3 Stillbirth.
Figuras y tablas -
Analysis 9.3

Comparison 9 Multivitamin plus iron and folic acid versus iron and folic acid, Outcome 3 Stillbirth.

Comparison 9 Multivitamin plus iron and folic acid versus iron and folic acid, Outcome 4 Congenital malformation.
Figuras y tablas -
Analysis 9.4

Comparison 9 Multivitamin plus iron and folic acid versus iron and folic acid, Outcome 4 Congenital malformation.

Comparison 10 Multivitamin without folic acid versus no multivitamin/folic acid, Outcome 1 Total fetal loss.
Figuras y tablas -
Analysis 10.1

Comparison 10 Multivitamin without folic acid versus no multivitamin/folic acid, Outcome 1 Total fetal loss.

Comparison 10 Multivitamin without folic acid versus no multivitamin/folic acid, Outcome 2 Early or late miscarriage.
Figuras y tablas -
Analysis 10.2

Comparison 10 Multivitamin without folic acid versus no multivitamin/folic acid, Outcome 2 Early or late miscarriage.

Comparison 10 Multivitamin without folic acid versus no multivitamin/folic acid, Outcome 3 Stillbirth.
Figuras y tablas -
Analysis 10.3

Comparison 10 Multivitamin without folic acid versus no multivitamin/folic acid, Outcome 3 Stillbirth.

Comparison 10 Multivitamin without folic acid versus no multivitamin/folic acid, Outcome 4 Congenital malformations.
Figuras y tablas -
Analysis 10.4

Comparison 10 Multivitamin without folic acid versus no multivitamin/folic acid, Outcome 4 Congenital malformations.

Comparison 11 Multivitamin with/without folic acid versus no multivitamin/folic acid, Outcome 1 Total fetal loss.
Figuras y tablas -
Analysis 11.1

Comparison 11 Multivitamin with/without folic acid versus no multivitamin/folic acid, Outcome 1 Total fetal loss.

Comparison 11 Multivitamin with/without folic acid versus no multivitamin/folic acid, Outcome 2 Early or late miscarriage.
Figuras y tablas -
Analysis 11.2

Comparison 11 Multivitamin with/without folic acid versus no multivitamin/folic acid, Outcome 2 Early or late miscarriage.

Comparison 11 Multivitamin with/without folic acid versus no multivitamin/folic acid, Outcome 3 Stillbirth.
Figuras y tablas -
Analysis 11.3

Comparison 11 Multivitamin with/without folic acid versus no multivitamin/folic acid, Outcome 3 Stillbirth.

Comparison 11 Multivitamin with/without folic acid versus no multivitamin/folic acid, Outcome 4 Congenital malformations.
Figuras y tablas -
Analysis 11.4

Comparison 11 Multivitamin with/without folic acid versus no multivitamin/folic acid, Outcome 4 Congenital malformations.

Comparison 12 Multivitamin plus folic acid versus folic acid, Outcome 1 Total fetal loss.
Figuras y tablas -
Analysis 12.1

Comparison 12 Multivitamin plus folic acid versus folic acid, Outcome 1 Total fetal loss.

Comparison 12 Multivitamin plus folic acid versus folic acid, Outcome 2 Early or late miscarriage.
Figuras y tablas -
Analysis 12.2

Comparison 12 Multivitamin plus folic acid versus folic acid, Outcome 2 Early or late miscarriage.

Comparison 12 Multivitamin plus folic acid versus folic acid, Outcome 3 Stillbirth.
Figuras y tablas -
Analysis 12.3

Comparison 12 Multivitamin plus folic acid versus folic acid, Outcome 3 Stillbirth.

Comparison 12 Multivitamin plus folic acid versus folic acid, Outcome 4 Congenital malformations.
Figuras y tablas -
Analysis 12.4

Comparison 12 Multivitamin plus folic acid versus folic acid, Outcome 4 Congenital malformations.

Comparison 13 Multivitamin without folic acid versus folic acid, Outcome 1 Total fetal loss.
Figuras y tablas -
Analysis 13.1

Comparison 13 Multivitamin without folic acid versus folic acid, Outcome 1 Total fetal loss.

Comparison 13 Multivitamin without folic acid versus folic acid, Outcome 2 Early or late miscarriage.
Figuras y tablas -
Analysis 13.2

Comparison 13 Multivitamin without folic acid versus folic acid, Outcome 2 Early or late miscarriage.

Comparison 13 Multivitamin without folic acid versus folic acid, Outcome 3 Stillbirth.
Figuras y tablas -
Analysis 13.3

Comparison 13 Multivitamin without folic acid versus folic acid, Outcome 3 Stillbirth.

Comparison 13 Multivitamin without folic acid versus folic acid, Outcome 4 Congenital malformations.
Figuras y tablas -
Analysis 13.4

Comparison 13 Multivitamin without folic acid versus folic acid, Outcome 4 Congenital malformations.

Comparison 14 Multivitamin with/without folic acid versus folic acid, Outcome 1 Total fetal loss.
Figuras y tablas -
Analysis 14.1

Comparison 14 Multivitamin with/without folic acid versus folic acid, Outcome 1 Total fetal loss.

Comparison 14 Multivitamin with/without folic acid versus folic acid, Outcome 2 Early of late miscarriage.
Figuras y tablas -
Analysis 14.2

Comparison 14 Multivitamin with/without folic acid versus folic acid, Outcome 2 Early of late miscarriage.

Comparison 14 Multivitamin with/without folic acid versus folic acid, Outcome 3 Stillbirth.
Figuras y tablas -
Analysis 14.3

Comparison 14 Multivitamin with/without folic acid versus folic acid, Outcome 3 Stillbirth.

Comparison 14 Multivitamin with/without folic acid versus folic acid, Outcome 4 Congenital malformations.
Figuras y tablas -
Analysis 14.4

Comparison 14 Multivitamin with/without folic acid versus folic acid, Outcome 4 Congenital malformations.

Comparison 15 Multivitamin with/without vitamin A versus vitamin A or placebo, Outcome 1 Total fetal loss.
Figuras y tablas -
Analysis 15.1

Comparison 15 Multivitamin with/without vitamin A versus vitamin A or placebo, Outcome 1 Total fetal loss.

Comparison 16 Multivitamin versus control, Outcome 1 Total fetal loss.
Figuras y tablas -
Analysis 16.1

Comparison 16 Multivitamin versus control, Outcome 1 Total fetal loss.

Comparison 16 Multivitamin versus control, Outcome 2 Stillbirth.
Figuras y tablas -
Analysis 16.2

Comparison 16 Multivitamin versus control, Outcome 2 Stillbirth.

Comparison 17 Multivitamin plus vitamin E versus multivitamin without vitamin E or control, Outcome 1 Total fetal loss.
Figuras y tablas -
Analysis 17.1

Comparison 17 Multivitamin plus vitamin E versus multivitamin without vitamin E or control, Outcome 1 Total fetal loss.

Comparison 17 Multivitamin plus vitamin E versus multivitamin without vitamin E or control, Outcome 2 Early or late miscarriage.
Figuras y tablas -
Analysis 17.2

Comparison 17 Multivitamin plus vitamin E versus multivitamin without vitamin E or control, Outcome 2 Early or late miscarriage.

Comparison 17 Multivitamin plus vitamin E versus multivitamin without vitamin E or control, Outcome 3 Stillbirth.
Figuras y tablas -
Analysis 17.3

Comparison 17 Multivitamin plus vitamin E versus multivitamin without vitamin E or control, Outcome 3 Stillbirth.

Comparison 18 Multivitamin plus folic acid versus no multivitamin/folic acid, Outcome 1 Total fetal loss.
Figuras y tablas -
Analysis 18.1

Comparison 18 Multivitamin plus folic acid versus no multivitamin/folic acid, Outcome 1 Total fetal loss.

Comparison 18 Multivitamin plus folic acid versus no multivitamin/folic acid, Outcome 2 Early or late miscarriage.
Figuras y tablas -
Analysis 18.2

Comparison 18 Multivitamin plus folic acid versus no multivitamin/folic acid, Outcome 2 Early or late miscarriage.

Comparison 18 Multivitamin plus folic acid versus no multivitamin/folic acid, Outcome 3 Stillbirth.
Figuras y tablas -
Analysis 18.3

Comparison 18 Multivitamin plus folic acid versus no multivitamin/folic acid, Outcome 3 Stillbirth.

Comparison 18 Multivitamin plus folic acid versus no multivitamin/folic acid, Outcome 4 Congenital malformations.
Figuras y tablas -
Analysis 18.4

Comparison 18 Multivitamin plus folic acid versus no multivitamin/folic acid, Outcome 4 Congenital malformations.

Comparison 19 Folic acid plus multivitamin versus no folic acid/multivitamin, Outcome 1 Total fetal loss.
Figuras y tablas -
Analysis 19.1

Comparison 19 Folic acid plus multivitamin versus no folic acid/multivitamin, Outcome 1 Total fetal loss.

Comparison 19 Folic acid plus multivitamin versus no folic acid/multivitamin, Outcome 2 Early or late miscarriage.
Figuras y tablas -
Analysis 19.2

Comparison 19 Folic acid plus multivitamin versus no folic acid/multivitamin, Outcome 2 Early or late miscarriage.

Comparison 19 Folic acid plus multivitamin versus no folic acid/multivitamin, Outcome 3 Stillbirth.
Figuras y tablas -
Analysis 19.3

Comparison 19 Folic acid plus multivitamin versus no folic acid/multivitamin, Outcome 3 Stillbirth.

Comparison 19 Folic acid plus multivitamin versus no folic acid/multivitamin, Outcome 4 Congenital malformations.
Figuras y tablas -
Analysis 19.4

Comparison 19 Folic acid plus multivitamin versus no folic acid/multivitamin, Outcome 4 Congenital malformations.

Comparison 20 Folic acid without multivitamin versus no folic acid/multivitamin, Outcome 1 Total fetal loss.
Figuras y tablas -
Analysis 20.1

Comparison 20 Folic acid without multivitamin versus no folic acid/multivitamin, Outcome 1 Total fetal loss.

Comparison 20 Folic acid without multivitamin versus no folic acid/multivitamin, Outcome 2 Early or late miscarriage.
Figuras y tablas -
Analysis 20.2

Comparison 20 Folic acid without multivitamin versus no folic acid/multivitamin, Outcome 2 Early or late miscarriage.

Comparison 20 Folic acid without multivitamin versus no folic acid/multivitamin, Outcome 3 Stillbirth.
Figuras y tablas -
Analysis 20.3

Comparison 20 Folic acid without multivitamin versus no folic acid/multivitamin, Outcome 3 Stillbirth.

Comparison 20 Folic acid without multivitamin versus no folic acid/multivitamin, Outcome 4 Congenital malformations.
Figuras y tablas -
Analysis 20.4

Comparison 20 Folic acid without multivitamin versus no folic acid/multivitamin, Outcome 4 Congenital malformations.

Comparison 21 Folic acid with/without multivitamin versus no folic acid/multivitamin, Outcome 1 Total fetal loss.
Figuras y tablas -
Analysis 21.1

Comparison 21 Folic acid with/without multivitamin versus no folic acid/multivitamin, Outcome 1 Total fetal loss.

Comparison 21 Folic acid with/without multivitamin versus no folic acid/multivitamin, Outcome 2 Early or late miscarriage.
Figuras y tablas -
Analysis 21.2

Comparison 21 Folic acid with/without multivitamin versus no folic acid/multivitamin, Outcome 2 Early or late miscarriage.

Comparison 21 Folic acid with/without multivitamin versus no folic acid/multivitamin, Outcome 3 Stillbirth.
Figuras y tablas -
Analysis 21.3

Comparison 21 Folic acid with/without multivitamin versus no folic acid/multivitamin, Outcome 3 Stillbirth.

Comparison 21 Folic acid with/without multivitamin versus no folic acid/multivitamin, Outcome 4 Congenital malformations.
Figuras y tablas -
Analysis 21.4

Comparison 21 Folic acid with/without multivitamin versus no folic acid/multivitamin, Outcome 4 Congenital malformations.

Comparison 22 Folic acis plus multivitamin versus multivitamin, Outcome 1 Total fetal loss.
Figuras y tablas -
Analysis 22.1

Comparison 22 Folic acis plus multivitamin versus multivitamin, Outcome 1 Total fetal loss.

Comparison 22 Folic acis plus multivitamin versus multivitamin, Outcome 2 Early or late miscarriage.
Figuras y tablas -
Analysis 22.2

Comparison 22 Folic acis plus multivitamin versus multivitamin, Outcome 2 Early or late miscarriage.

Comparison 22 Folic acis plus multivitamin versus multivitamin, Outcome 3 Stillbirth.
Figuras y tablas -
Analysis 22.3

Comparison 22 Folic acis plus multivitamin versus multivitamin, Outcome 3 Stillbirth.

Comparison 22 Folic acis plus multivitamin versus multivitamin, Outcome 4 Congenital malformations.
Figuras y tablas -
Analysis 22.4

Comparison 22 Folic acis plus multivitamin versus multivitamin, Outcome 4 Congenital malformations.

Comparison 23 Folic acid without multivitamin versus multivitamin, Outcome 1 Total fetal loss.
Figuras y tablas -
Analysis 23.1

Comparison 23 Folic acid without multivitamin versus multivitamin, Outcome 1 Total fetal loss.

Comparison 23 Folic acid without multivitamin versus multivitamin, Outcome 2 Early or late miscarriage.
Figuras y tablas -
Analysis 23.2

Comparison 23 Folic acid without multivitamin versus multivitamin, Outcome 2 Early or late miscarriage.

Comparison 23 Folic acid without multivitamin versus multivitamin, Outcome 3 Stillbirth.
Figuras y tablas -
Analysis 23.3

Comparison 23 Folic acid without multivitamin versus multivitamin, Outcome 3 Stillbirth.

Comparison 23 Folic acid without multivitamin versus multivitamin, Outcome 4 Congenital malformations.
Figuras y tablas -
Analysis 23.4

Comparison 23 Folic acid without multivitamin versus multivitamin, Outcome 4 Congenital malformations.

Comparison 24 Folic acid with or without multivitamin versus multivitamin, Outcome 1 Total fetal loss.
Figuras y tablas -
Analysis 24.1

Comparison 24 Folic acid with or without multivitamin versus multivitamin, Outcome 1 Total fetal loss.

Comparison 24 Folic acid with or without multivitamin versus multivitamin, Outcome 2 Early or late miscarriage.
Figuras y tablas -
Analysis 24.2

Comparison 24 Folic acid with or without multivitamin versus multivitamin, Outcome 2 Early or late miscarriage.

Comparison 24 Folic acid with or without multivitamin versus multivitamin, Outcome 3 Stillbirth.
Figuras y tablas -
Analysis 24.3

Comparison 24 Folic acid with or without multivitamin versus multivitamin, Outcome 3 Stillbirth.

Comparison 24 Folic acid with or without multivitamin versus multivitamin, Outcome 4 Congenital malformations.
Figuras y tablas -
Analysis 24.4

Comparison 24 Folic acid with or without multivitamin versus multivitamin, Outcome 4 Congenital malformations.

Comparison 25 Folic acid plus iron versus iron, Outcome 1 Total fetal loss.
Figuras y tablas -
Analysis 25.1

Comparison 25 Folic acid plus iron versus iron, Outcome 1 Total fetal loss.

Comparison 25 Folic acid plus iron versus iron, Outcome 2 Early or late miscarriage.
Figuras y tablas -
Analysis 25.2

Comparison 25 Folic acid plus iron versus iron, Outcome 2 Early or late miscarriage.

Comparison 25 Folic acid plus iron versus iron, Outcome 3 Stillbirth.
Figuras y tablas -
Analysis 25.3

Comparison 25 Folic acid plus iron versus iron, Outcome 3 Stillbirth.

Comparison 26 Folic acid plus iron and antimalarials versus iron and antimalarials, Outcome 1 Total fetal loss.
Figuras y tablas -
Analysis 26.1

Comparison 26 Folic acid plus iron and antimalarials versus iron and antimalarials, Outcome 1 Total fetal loss.

Comparison 26 Folic acid plus iron and antimalarials versus iron and antimalarials, Outcome 2 Early or late miscarriage.
Figuras y tablas -
Analysis 26.2

Comparison 26 Folic acid plus iron and antimalarials versus iron and antimalarials, Outcome 2 Early or late miscarriage.

Comparison 27 Antioxidant vitamin supplementation, Outcome 1 Early or late miscarriage.
Figuras y tablas -
Analysis 27.1

Comparison 27 Antioxidant vitamin supplementation, Outcome 1 Early or late miscarriage.

Summary of findings for the main comparison. Vitamin C and vitamin E versus placebo for preventing miscarriage

Vitamin C plus vitamin E versus control for preventing miscarriage

Population: pregnant women
Setting: Australia, Brazil, Canada, Scotland, UK, USA
Intervention: vitamin C and vitamin E
Comparison: placebo

Outcomes

Anticipated absolute effects* (95% CI)

Relative effect
(95% CI)

№ of participants
(studies)

Quality of the evidence
(GRADE)

Comments

Risk with placebo

Risk with Vitamin C plus vitamin E

Total fetal loss

Study population

RR 1.14
(0.92 to 1.40)

18,949
(7 RCTs)

⊕⊕⊕⊕
HIGH 1

17 per 1000

20 per 1000
(16 to 24)

Moderate

14 per 1000

16 per 1000
(13 to 20)

Early or late miscarriage

Study population

RR 0.90
(0.65 to 1.26)

13,346
(4 RCTs)

⊕⊕⊕⊝
MODERATE 2

9 per 1000

9 per 1000
(7 to 12)

Moderate

8 per 1000

8 per 1000
(6 to 11)

Stillbirth

Study population

RR 1.31
(0.97 to 1.76)

21,442
(7 RCTs)

⊕⊕⊕⊝
MODERATE 2

8 per 1000

10 per 1000
(7 to 13)

Moderate

7 per 1000

9 per 1000
(7 to 12)

Any adverse effects of vitamin supplementation sufficient to stop supplementation

Study population

RR 1.16
(0.39 to 3.41)

739
(1 RCT)

⊕⊕⊕⊝
MODERATE 2 3

16 per 1000

19 per 1000
(6 to 56)

*The risk in the intervention group (and its 95% confidence interval) is based on the assumed risk in the comparison group and the relative effect of the intervention (and its 95% CI).

CI: Confidence interval; RR: Risk ratio

GRADE Working Group grades of evidence
High quality: We are very confident that the true effect lies close to that of the estimate of the effect
Moderate quality: We are moderately confident in the effect estimate: The true effect is likely to be close to the estimate of the effect, but there is a possibility that it is substantially different
Low quality: Our confidence in the effect estimate is limited: The true effect may be substantially different from the estimate of the effect
Very low quality: We have very little confidence in the effect estimate: The true effect is likely to be substantially different from the estimate of effect

1 Not effective but 95% CI is narrow and precise.

2 Non significant with wide 95% CI.

3 Small sample size.

Figuras y tablas -
Summary of findings for the main comparison. Vitamin C and vitamin E versus placebo for preventing miscarriage
Summary of findings 2. Vitamin A plus iron plus folate versus iron plus folate for preventing miscarriage

Vitamin A plus iron plus folate versus iron plus folate for preventing miscarriage

Population: pregnant women
Settings: Indonesia, Malawi
Intervention: vitamin A plus iron plus folate
Comparison: iron plus folate

Outcomes

Anticipated absolute effects* (95% CI)

Relative effect
(95% CI)

№ of participants
(studies)

Quality of the evidence
(GRADE)

Comments

Risk with placebo

Risk with Vitamin A

Total fetal loss (including miscarriages or combined miscarriages and stillbirths) ‐ Vitamin A + iron + folate versus iron + folate

Study population

RR 1.01
(0.61 to 1.66)

1640
(3 RCTs)

⊕⊕⊝⊝
LOW 1 2

37 per 1000

37 per 1000
(22 to 61)

Moderate

59 per 1,000

60 per 1,000

(36 to 98)

Early or late miscarriage ‐ Vitamin A + iron + folate versus iron + folate

Study population

RR 0.86
(0.46 to 1.62)

1397
(2 RCTs)

⊕⊕⊝⊝
LOW 1 2

31 per 1000

26 per 1000
(14 to 50)

Moderate

50 per 1,000

43 per 1,000

(23 to 80)

Stillbirth ‐ Vitamin A + iron + folate versus iron + folate

Study population

RR 1.29
(0.57 to 2.91)

1640
(3 RCTs)

⊕⊕⊝⊝
LOW 1 2

13 per 1000

16 per 1000
(7 to 37)

Moderate

21 per 1,000

27 per 1,000

(12 to 61)

Any adverse effects

See comments.

No studies reported this outcome.

*The risk in the intervention group (and its 95% confidence interval) is based on the assumed risk in the comparison group and the relative effect of the intervention (and its 95% CI).

CI: Confidence interval; RR: Risk ratio

GRADE Working Group grades of evidence
High quality: We are very confident that the true effect lies close to that of the estimate of the effect
Moderate quality: We are moderately confident in the effect estimate: The true effect is likely to be close to the estimate of the effect, but there is a possibility that it is substantially different
Low quality: Our confidence in the effect estimate is limited: The true effect may be substantially different from the estimate of the effect
Very low quality: We have very little confidence in the effect estimate: The true effect is likely to be substantially different from the estimate of effect

1 High and unclear risk of attrition bias.

2 Wide 95% CI.

Figuras y tablas -
Summary of findings 2. Vitamin A plus iron plus folate versus iron plus folate for preventing miscarriage
Summary of findings 3. Multivitamin plus iron plus folate versus iron plus folate for preventing miscarriage

Multivitamin plus iron plus folate versus iron plus folate for preventing miscarriage

Population: pregnant women
Settings: Bangladesh, Barkino Faso, Indonesia, Nepal, Niger, Pakistan, Tanzania
Intervention: vitamin A plus iron plus folate
Comparison: iron plus folate

Outcomes

Anticipated absolute effects* (95% CI)

Relative effect
(95% CI)

№ of participants
(studies)

Quality of the evidence
(GRADE)

Comments

Risk with placebo

Risk with Multivitamin

Total fetal loss (including miscarriages or combined miscarriages and stillbirths) ‐ Multivitamins + iron + folic acid versus iron + folic acid

Study population

RR 0.96
(0.93 to 1.00)

94,948
(10 RCTs)

⊕⊕⊕⊕
HIGH

136 per 1000

130 per 1000
(126 to 136)

Moderate

218 per 1,000

209 per 1,000

(202 to 218)

Early or late miscarriage ‐ Multivitamin + iron + folic acid versus iron + folic acid

Study population

RR 0.98
(0.94 to 1.03)

94948
(10 RCTs)

⊕⊕⊕⊝
MODERATE 1,2

84 per 1000

83 per 1000
(79 to 87)

Moderate

134 per 1,000

132 per 1,000

(126 to 138)

Stillbirth ‐ Multivitamin + iron + folic acid versus iron + folic acid

Study population

RR 0.92
(0.85 to 0.99)

79,851
(10 RCTs)

⊕⊕⊕⊕
HIGH

29 per 1000

26 per 1000
(24 to 28)

Moderate

46 per 1,000

43 per 1,000

(39 to 46)

Any adverse effects

See comments

No studies reported this outcome

*The risk in the intervention group (and its 95% confidence interval) is based on the assumed risk in the comparison group and the relative effect of the intervention (and its 95% CI).
CI: Confidence interval; RR: Risk ratio

GRADE Working Group grades of evidence
High quality: We are very confident that the true effect lies close to that of the estimate of the effect
Moderate quality: We are moderately confident in the effect estimate: The true effect is likely to be close to the estimate of the effect, but there is a possibility that it is substantially different
Low quality: Our confidence in the effect estimate is limited: The true effect may be substantially different from the estimate of the effect
Very low quality: We have very little confidence in the effect estimate: The true effect is likely to be substantially different from the estimate of effect

1 Publication bias detected by funnel plot.

2 Wide confidence interval crossing the line of no effect.

Figuras y tablas -
Summary of findings 3. Multivitamin plus iron plus folate versus iron plus folate for preventing miscarriage
Comparison 1. Vitamin C plus vitamin E versus placebo

Outcome or subgroup title

No. of studies

No. of participants

Statistical method

Effect size

1 Total fetal loss Show forest plot

7

18949

Risk Ratio (M‐H, Fixed, 95% CI)

1.14 [0.92, 1.40]

2 Early or late miscarriage Show forest plot

4

13346

Risk Ratio (M‐H, Fixed, 95% CI)

0.90 [0.65, 1.26]

3 Stillbirth Show forest plot

7

21442

Risk Ratio (M‐H, Fixed, 95% CI)

1.31 [0.97, 1.76]

4 Congenital malformations Show forest plot

5

8334

Risk Ratio (M‐H, Fixed, 95% CI)

1.17 [0.84, 1.62]

5 Any adverse effects of vitamin supplementation sufficient to stop supplementation Show forest plot

1

739

Risk Ratio (M‐H, Fixed, 95% CI)

1.16 [0.39, 3.41]

Figuras y tablas -
Comparison 1. Vitamin C plus vitamin E versus placebo
Comparison 2. Vitamin C versus no supplement/placebo

Outcome or subgroup title

No. of studies

No. of participants

Statistical method

Effect size

1 Total fetal loss Show forest plot

2

224

Risk Ratio (M‐H, Fixed, 95% CI)

1.28 [0.58, 2.83]

2 Early or late miscarriage Show forest plot

2

224

Risk Ratio (M‐H, Fixed, 95% CI)

1.17 [0.52, 2.65]

3 Stillbirth Show forest plot

1

200

Risk Ratio (M‐H, Fixed, 95% CI)

3.0 [0.12, 72.77]

Figuras y tablas -
Comparison 2. Vitamin C versus no supplement/placebo
Comparison 3. Vitamin C plus multivitamins versus placebo plus multivitamins or multivitamins alone

Outcome or subgroup title

No. of studies

No. of participants

Statistical method

Effect size

1 Total fetal loss Show forest plot

1

406

Risk Ratio (M‐H, Fixed, 95% CI)

1.32 [0.63, 2.77]

2 Early or late miscarriage Show forest plot

2

790

Risk Ratio (M‐H, Fixed, 95% CI)

1.19 [0.79, 1.79]

Figuras y tablas -
Comparison 3. Vitamin C plus multivitamins versus placebo plus multivitamins or multivitamins alone
Comparison 4. Vitamin A plus iron and folate versus iron and folate

Outcome or subgroup title

No. of studies

No. of participants

Statistical method

Effect size

1 Total fetal loss Show forest plot

3

1640

Risk Ratio (Fixed, 95% CI)

1.01 [0.61, 1.66]

2 Early or late miscarriage Show forest plot

2

1397

Risk Ratio (Fixed, 95% CI)

0.86 [0.46, 1.62]

3 Stillbirth Show forest plot

3

1640

Risk Ratio (Fixed, 95% CI)

1.29 [0.57, 2.91]

Figuras y tablas -
Comparison 4. Vitamin A plus iron and folate versus iron and folate
Comparison 5. Vitamin A versus placebo

Outcome or subgroup title

No. of studies

No. of participants

Statistical method

Effect size

1 Total fetal loss Show forest plot

3

52480

Risk Ratio (Random, 95% CI)

1.05 [0.90, 1.23]

2 Early of late miscarriage Show forest plot

1

39668

Risk Ratio (Fixed, 95% CI)

0.98 [0.92, 1.04]

3 Stillbirth Show forest plot

1

39668

Risk Ratio (Fixed, 95% CI)

0.95 [0.86, 1.06]

Figuras y tablas -
Comparison 5. Vitamin A versus placebo
Comparison 6. Beta‐carotene versus placebo

Outcome or subgroup title

No. of studies

No. of participants

Statistical method

Effect size

1 Total fetal loss Show forest plot

2

51163

Risk Ratio (Fixed, 95% CI)

1.02 [0.98, 1.07]

2 Early or late miscarriage Show forest plot

1

39860

Risk Ratio (Fixed, 95% CI)

1.00 [0.94, 1.06]

3 Stillbirth Show forest plot

1

39860

Risk Ratio (Fixed, 95% CI)

1.09 [0.98, 1.20]

Figuras y tablas -
Comparison 6. Beta‐carotene versus placebo
Comparison 7. Vitamin A or beta‐carotene versus placebo

Outcome or subgroup title

No. of studies

No. of participants

Statistical method

Effect size

1 Total fetal loss Show forest plot

1

17373

Risk Ratio (Fixed, 95% CI)

1.05 [0.91, 1.21]

Figuras y tablas -
Comparison 7. Vitamin A or beta‐carotene versus placebo
Comparison 8. Vitamin A (with/without multivitamins) versus multivitamins or placebo

Outcome or subgroup title

No. of studies

No. of participants

Statistical method

Effect size

1 Total fetal loss Show forest plot

1

1074

Risk Ratio (Fixed, 95% CI)

0.80 [0.53, 1.21]

2 Early or late miscarriage Show forest plot

1

1075

Risk Ratio (Fixed, 95% CI)

0.76 [0.37, 1.55]

3 Stillbirth Show forest plot

1

1075

Risk Ratio (Fixed, 95% CI)

1.04 [0.60, 1.79]

Figuras y tablas -
Comparison 8. Vitamin A (with/without multivitamins) versus multivitamins or placebo
Comparison 9. Multivitamin plus iron and folic acid versus iron and folic acid

Outcome or subgroup title

No. of studies

No. of participants

Statistical method

Effect size

1 Total fetal loss Show forest plot

10

94948

Risk Ratio (Fixed, 95% CI)

0.96 [0.93, 1.00]

2 Early or late miscarriage Show forest plot

10

94948

Risk Ratio (Fixed, 95% CI)

0.98 [0.94, 1.03]

3 Stillbirth Show forest plot

10

79851

Risk Ratio (Fixed, 95% CI)

0.92 [0.85, 0.99]

4 Congenital malformation Show forest plot

1

1200

Risk Ratio (M‐H, Fixed, 95% CI)

1.0 [0.14, 7.08]

Figuras y tablas -
Comparison 9. Multivitamin plus iron and folic acid versus iron and folic acid
Comparison 10. Multivitamin without folic acid versus no multivitamin/folic acid

Outcome or subgroup title

No. of studies

No. of participants

Statistical method

Effect size

1 Total fetal loss Show forest plot

1

907

Risk Ratio (Fixed, 95% CI)

0.49 [0.34, 0.70]

2 Early or late miscarriage Show forest plot

1

907

Risk Ratio (Fixed, 95% CI)

0.89 [0.59, 1.34]

3 Stillbirth Show forest plot

1

907

Risk Ratio (Fixed, 95% CI)

0.14 [0.01, 2.77]

4 Congenital malformations Show forest plot

1

907

Risk Ratio (M‐H, Fixed, 95% CI)

1.60 [0.53, 4.86]

Figuras y tablas -
Comparison 10. Multivitamin without folic acid versus no multivitamin/folic acid
Comparison 11. Multivitamin with/without folic acid versus no multivitamin/folic acid

Outcome or subgroup title

No. of studies

No. of participants

Statistical method

Effect size

1 Total fetal loss Show forest plot

1

1368

Risk Ratio (Fixed, 95% CI)

0.91 [0.65, 1.27]

2 Early or late miscarriage Show forest plot

1

1368

Risk Ratio (Fixed, 95% CI)

0.95 [0.67, 1.34]

3 Stillbirth Show forest plot

1

1368

Risk Ratio (Fixed, 95% CI)

0.33 [0.06, 1.98]

4 Congenital malformations Show forest plot

1

1368

Risk Ratio (M‐H, Fixed, 95% CI)

1.99 [0.75, 5.26]

Figuras y tablas -
Comparison 11. Multivitamin with/without folic acid versus no multivitamin/folic acid
Comparison 12. Multivitamin plus folic acid versus folic acid

Outcome or subgroup title

No. of studies

No. of participants

Statistical method

Effect size

1 Total fetal loss Show forest plot

3

5012

Risk Ratio (Fixed, 95% CI)

1.04 [0.88, 1.23]

2 Early or late miscarriage Show forest plot

3

5012

Risk Ratio (Fixed, 95% CI)

0.97 [0.80, 1.18]

3 Stillbirth Show forest plot

3

4316

Risk Ratio (Fixed, 95% CI)

1.32 [0.93, 1.88]

4 Congenital malformations Show forest plot

2

1096

Risk Ratio (M‐H, Fixed, 95% CI)

1.71 [0.72, 4.04]

Figuras y tablas -
Comparison 12. Multivitamin plus folic acid versus folic acid
Comparison 13. Multivitamin without folic acid versus folic acid

Outcome or subgroup title

No. of studies

No. of participants

Statistical method

Effect size

1 Total fetal loss Show forest plot

2

1090

Risk Ratio (Fixed, 95% CI)

0.90 [0.62, 1.30]

2 Early or late miscarriage Show forest plot

2

1090

Risk Ratio (Fixed, 95% CI)

0.89 [0.61, 1.31]

3 Stillbirth Show forest plot

2

1090

Risk Ratio (Random, 95% CI)

0.99 [0.04, 22.90]

4 Congenital malformations Show forest plot

2

1090

Risk Ratio (M‐H, Fixed, 95% CI)

1.61 [0.67, 3.85]

Figuras y tablas -
Comparison 13. Multivitamin without folic acid versus folic acid
Comparison 14. Multivitamin with/without folic acid versus folic acid

Outcome or subgroup title

No. of studies

No. of participants

Statistical method

Effect size

1 Total fetal loss Show forest plot

2

1644

Risk Ratio (Fixed, 95% CI)

0.96 [0.70, 1.33]

2 Early of late miscarriage Show forest plot

2

1644

Risk Ratio (Fixed, 95% CI)

0.96 [0.70, 1.33]

3 Stillbirth Show forest plot

2

1644

Risk Ratio (Fixed, 95% CI)

0.79 [0.15, 4.10]

4 Congenital malformations Show forest plot

2

1644

Risk Ratio (M‐H, Fixed, 95% CI)

1.66 [0.76, 3.63]

Figuras y tablas -
Comparison 14. Multivitamin with/without folic acid versus folic acid
Comparison 15. Multivitamin with/without vitamin A versus vitamin A or placebo

Outcome or subgroup title

No. of studies

No. of participants

Statistical method

Effect size

1 Total fetal loss Show forest plot

1

1074

Risk Ratio (Fixed, 95% CI)

0.60 [0.39, 0.92]

Figuras y tablas -
Comparison 15. Multivitamin with/without vitamin A versus vitamin A or placebo
Comparison 16. Multivitamin versus control

Outcome or subgroup title

No. of studies

No. of participants

Statistical method

Effect size

1 Total fetal loss Show forest plot

1

5021

Risk Ratio (Fixed, 95% CI)

0.83 [0.58, 1.17]

2 Stillbirth Show forest plot

1

5021

Risk Ratio (Fixed, 95% CI)

0.83 [0.58, 1.17]

Figuras y tablas -
Comparison 16. Multivitamin versus control
Comparison 17. Multivitamin plus vitamin E versus multivitamin without vitamin E or control

Outcome or subgroup title

No. of studies

No. of participants

Statistical method

Effect size

1 Total fetal loss Show forest plot

1

823

Risk Ratio (Fixed, 95% CI)

0.92 [0.46, 1.83]

2 Early or late miscarriage Show forest plot

1

823

Risk Ratio (Fixed, 95% CI)

1.04 [0.26, 4.13]

3 Stillbirth Show forest plot

1

823

Risk Ratio (Fixed, 95% CI)

0.88 [0.39, 1.98]

Figuras y tablas -
Comparison 17. Multivitamin plus vitamin E versus multivitamin without vitamin E or control
Comparison 18. Multivitamin plus folic acid versus no multivitamin/folic acid

Outcome or subgroup title

No. of studies

No. of participants

Statistical method

Effect size

1 Total fetal loss Show forest plot

3

6883

Risk Ratio (Random, 95% CI)

1.00 [0.75, 1.34]

2 Early or late miscarriage Show forest plot

3

6883

Risk Ratio (Random, 95% CI)

0.99 [0.72, 1.38]

3 Stillbirth Show forest plot

3

6883

Risk Ratio (Fixed, 95% CI)

1.04 [0.51, 2.10]

4 Congenital malformations Show forest plot

2

5777

Risk Ratio (M‐H, Fixed, 95% CI)

1.69 [0.81, 3.53]

Figuras y tablas -
Comparison 18. Multivitamin plus folic acid versus no multivitamin/folic acid
Comparison 19. Folic acid plus multivitamin versus no folic acid/multivitamin

Outcome or subgroup title

No. of studies

No. of participants

Statistical method

Effect size

1 Total fetal loss Show forest plot

3

6883

Risk Ratio (M‐H, Random, 95% CI)

1.00 [0.75, 1.34]

2 Early or late miscarriage Show forest plot

3

6883

Risk Ratio (M‐H, Random, 95% CI)

0.99 [0.72, 1.38]

3 Stillbirth Show forest plot

3

6883

Risk Ratio (M‐H, Fixed, 95% CI)

1.03 [0.51, 2.09]

4 Congenital malformations Show forest plot

2

5777

Risk Ratio (M‐H, Fixed, 95% CI)

1.69 [0.81, 3.53]

Figuras y tablas -
Comparison 19. Folic acid plus multivitamin versus no folic acid/multivitamin
Comparison 20. Folic acid without multivitamin versus no folic acid/multivitamin

Outcome or subgroup title

No. of studies

No. of participants

Statistical method

Effect size

1 Total fetal loss Show forest plot

1

903

Risk Ratio (M‐H, Fixed, 95% CI)

0.95 [0.64, 1.40]

2 Early or late miscarriage Show forest plot

1

903

Risk Ratio (M‐H, Fixed, 95% CI)

0.97 [0.65, 1.44]

3 Stillbirth Show forest plot

1

903

Risk Ratio (M‐H, Fixed, 95% CI)

0.67 [0.11, 4.02]

4 Congenital malformations Show forest plot

1

903

Risk Ratio (M‐H, Fixed, 95% CI)

1.42 [0.45, 4.43]

Figuras y tablas -
Comparison 20. Folic acid without multivitamin versus no folic acid/multivitamin
Comparison 21. Folic acid with/without multivitamin versus no folic acid/multivitamin

Outcome or subgroup title

No. of studies

No. of participants

Statistical method

Effect size

1 Total fetal loss Show forest plot

1

1364

Risk Ratio (M‐H, Fixed, 95% CI)

0.97 [0.69, 1.35]

2 Early or late miscarriage Show forest plot

1

1364

Risk Ratio (M‐H, Fixed, 95% CI)

0.99 [0.70, 1.39]

3 Stillbirth Show forest plot

1

1364

Risk Ratio (M‐H, Fixed, 95% CI)

0.67 [0.15, 2.96]

4 Congenital malformations Show forest plot

1

1364

Risk Ratio (M‐H, Fixed, 95% CI)

1.90 [0.71, 5.04]

Figuras y tablas -
Comparison 21. Folic acid with/without multivitamin versus no folic acid/multivitamin
Comparison 22. Folic acis plus multivitamin versus multivitamin

Outcome or subgroup title

No. of studies

No. of participants

Statistical method

Effect size

1 Total fetal loss Show forest plot

2

1102

Risk Ratio (M‐H, Fixed, 95% CI)

1.15 [0.80, 1.67]

2 Early or late miscarriage Show forest plot

2

1102

Risk Ratio (M‐H, Fixed, 95% CI)

1.16 [0.80, 1.69]

3 Stillbirth Show forest plot

2

1102

Risk Ratio (M‐H, Random, 95% CI)

1.00 [0.04, 22.55]

4 Congenital malformations Show forest plot

2

1102

Risk Ratio (M‐H, Random, 95% CI)

0.93 [0.28, 3.12]

Figuras y tablas -
Comparison 22. Folic acis plus multivitamin versus multivitamin
Comparison 23. Folic acid without multivitamin versus multivitamin

Outcome or subgroup title

No. of studies

No. of participants

Statistical method

Effect size

1 Total fetal loss Show forest plot

2

1090

Risk Ratio (M‐H, Fixed, 95% CI)

1.12 [0.77, 1.62]

2 Early or late miscarriage Show forest plot

2

1090

Risk Ratio (M‐H, Fixed, 95% CI)

1.12 [0.77, 1.64]

3 Stillbirth Show forest plot

2

1090

Risk Ratio (M‐H, Fixed, 95% CI)

4.97 [0.58, 42.29]

4 Congenital malformations Show forest plot

2

1090

Risk Ratio (M‐H, Fixed, 95% CI)

0.62 [0.26, 1.49]

Figuras y tablas -
Comparison 23. Folic acid without multivitamin versus multivitamin
Comparison 24. Folic acid with or without multivitamin versus multivitamin

Outcome or subgroup title

No. of studies

No. of participants

Statistical method

Effect size

1 Total fetal loss Show forest plot

2

1644

Risk Ratio (M‐H, Fixed, 95% CI)

1.14 [0.82, 1.57]

2 Early or late miscarriage Show forest plot

2

1642

Risk Ratio (M‐H, Fixed, 95% CI)

1.09 [0.79, 1.51]

3 Stillbirth Show forest plot

2

1644

Risk Ratio (M‐H, Random, 95% CI)

0.69 [0.02, 28.39]

4 Congenital malformations Show forest plot

2

1644

Risk Ratio (M‐H, Random, 95% CI)

0.68 [0.19, 2.51]

Figuras y tablas -
Comparison 24. Folic acid with or without multivitamin versus multivitamin
Comparison 25. Folic acid plus iron versus iron

Outcome or subgroup title

No. of studies

No. of participants

Statistical method

Effect size

1 Total fetal loss Show forest plot

1

75

Risk Ratio (M‐H, Fixed, 95% CI)

0.23 [0.01, 4.59]

2 Early or late miscarriage Show forest plot

1

75

Risk Ratio (M‐H, Fixed, 95% CI)

0.38 [0.02, 9.03]

3 Stillbirth Show forest plot

1

75

Risk Ratio (M‐H, Fixed, 95% CI)

0.38 [0.02, 9.03]

Figuras y tablas -
Comparison 25. Folic acid plus iron versus iron
Comparison 26. Folic acid plus iron and antimalarials versus iron and antimalarials

Outcome or subgroup title

No. of studies

No. of participants

Statistical method

Effect size

1 Total fetal loss Show forest plot

1

160

Risk Ratio (M‐H, Fixed, 95% CI)

13.0 [0.74, 226.98]

2 Early or late miscarriage Show forest plot

1

160

Risk Ratio (M‐H, Fixed, 95% CI)

13.0 [0.74, 226.98]

Figuras y tablas -
Comparison 26. Folic acid plus iron and antimalarials versus iron and antimalarials
Comparison 27. Antioxidant vitamin supplementation

Outcome or subgroup title

No. of studies

No. of participants

Statistical method

Effect size

1 Early or late miscarriage Show forest plot

1

110

Risk Ratio (M‐H, Fixed, 95% CI)

1.12 [0.24, 5.29]

Figuras y tablas -
Comparison 27. Antioxidant vitamin supplementation