Comment: There is insufficient reliable evidence on the effects of various vitamin and mineral combinations for preventing miscarriage.
| Reference | Study type | Population | Intervention and comparison | Outcomes | Risk of bias |
|---|---|---|---|---|---|
| SR=systematic review | |||||
| «Balogun OO, da Silva Lopes K, Ota E, ym. Vitamin s...»1 | SR | Pregnant women (less than 20 weeks' gestation) or women in the reproductive age regardless
of whether they are at low or high risk of having a miscarriage. North America, Europe, Africa, Asia, Australia (Oceania), South America |
RCTs comparing supplementation that started prior to conception, periconceptionally or in early pregnancy (less than 20 weeks' gestation) with one or more vitamins with either placebo, other vitamins, no vitamins or other interventions. | Primary: total fetal loss, early or late miscarriage. Secondary: stillbirth, congenital malformations, adverse effects. |
Low |
| Reference | Comments |
|---|---|
| «Balogun OO, da Silva Lopes K, Ota E, ym. Vitamin s...»1 | There was no consistency amongst trials with regards to the definition of miscarriage.
For some trials, miscarriage was considered to occur up until 26 or 28 weeks' gestation,
while other studies reported miscarriage as pregnancy loss prior to 20 weeks' gestation.
Most of the studies included in this review did not originally set out to examine the effect of vitamin supplementation on the risk of miscarriage. |
Results
| Reference | Intervention and comparison/outcome |
Number of studies and number of patients (I/C) | Absolute number of events (%) I | Absolute number of events (%) C | Relative effect (95% CI) |
|---|---|---|---|---|---|
| Level of evidence: moderate.The level of evidence is downgraded due to study limitations and imprecision.
I=intervention; C=comparison; CI=confidence interval |
|||||
| «Balogun OO, da Silva Lopes K, Ota E, ym. Vitamin s...»1 | Vitamin C and vitamin E versus placebo1 | 4 (6678/6668) | 66 (0,9) | 73 (1,1) | RR 0,9 (0,65–1,26) |
| «Balogun OO, da Silva Lopes K, Ota E, ym. Vitamin s...»1 | Folic acid plus multivitamin versus no folic acid/multivitamin2 | 3 (3511/3372) | 352 (10) | 309 (9,2) | RR 0,99 (0,72–1,38) |
| «Balogun OO, da Silva Lopes K, Ota E, ym. Vitamin s...»1 | Folic acid without multivitamin versus no folic acid/multivitamin3 | 1 (449/454) |
42 (9,3) | 44 (9,7) | RR 0,97 (0,65-1,44) |
| Reference | Intervention and comparison/ outcome |
Number of studies and number of patients (I/C) | Absolute number of events (%) I | Absolute number of events (%) C | Relative effect (95% CI) |
|---|---|---|---|---|---|
| Level of evidence: moderate The level of evidence is downgraded due to imprecision.
I=intervention; C=comparison; CI=confidence interval |
|||||
| «Balogun OO, da Silva Lopes K, Ota E, ym. Vitamin s...»1 | Vitamin C plus vitamin E versus placebo | 1 RCT (371/368) | 7 (1.9) | 6 (1.6) | RR 1.16 (0.39–3.41) |