Summary of findings 1. Myo‐inositol for preventing gestational diabetes: maternal outcomes.
| Antenatal supplementation with myo‐inositol for preventing gestational diabetes | ||||||
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Patient or population: pregnant women (women with pre‐existing type 1 or type 2 diabetes are NOT included)
Intervention: myo‐inositol Setting: hospital Comparison: folic acid or placebo | ||||||
| Outcomes | Anticipated absolute effects* (95% CI) | Relative effect (95% CI) | № of participants (studies) | Certainty of the evidence (GRADE) | Comments | |
| Risk with control | Risk with myo‐inositol | |||||
| Gestational diabetes mellitus | Study population | RR 0.53 (0.31 to 0.90) | 1140 (6 RCTs) | ⊕⊝⊝⊝ Very lowa,b,c |
GDM diagnosed using IADPSG 2010 criteria Random‐effects model |
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| 217 per 1000 | 115 per 1,000 (67 to 196) |
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| Weight gain during pregnancy | Comparator | The mean weight gain during pregnancy in the intervention group was 0.25 kg lower (1.26 kg fewer to 0.76 kg more) | ‐ | 831 (4 RCTs) | ⊕⊝⊝⊝ Very lowb,c,d,e | Random‐effects model |
| Hypertensive disorders of pregnancy | Study population | RR 0.34 (0.19 to 0.61) | 1052 (5 RCTs) | ⊕⊕⊝⊝ Lowc,f | Random‐effects model | |
| 86 per 1,000 | 29 per 1,000 (16 to 53) | |||||
| Caesarean section | Study population | RR 0.91 (0.77 to 1.07) | 829 (4 RCTs) | ⊕⊕⊝⊝ Lowc,g | ||
| 430 per 1,000 | 391 per 1,000 (331 to 460) | |||||
| Perineal trauma | Study population | RR 4.00 (0.45 to 35.25) | 234 (1 RCT) |
⊕⊝⊝⊝ Very lowh,i,j | ||
| 9 per 1,000 | 34 per 1,000 (4 to 301) |
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| Postnatal depression | See comments | Not estimable | (0 studies) | No data reported this outcome in any of the included studies | ||
| Development of subsequent type 2 diabetes mellitus | See comments | Not estimable | (0 studies) | No data reported this outcome in any of the included studies | ||
| *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 certainty: we are very confident that the true effect lies close to that of the estimate of the effect Moderate certainty: 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 certainty: our confidence in the effect estimate is limited: The true effect may be substantially different from the estimate of the effect Very low certainty: we have very little confidence in the effect estimate: The true effect is likely to be substantially different from the estimate of effect | ||||||
a. Downgraded (‐1) for serious limitations in study design: due to unclear risk of selection bias in two of the six included studies; five of the six included studies were at high risk of performance bias; two of the six included studies were at high risk of detection bias; one study was at high risk of attrition bias.
b. Downgraded (‐1) for serious inconsistency; considerable heterogeneity, possible due to different study populations.
c. Downgraded (‐1) for serious indirectness; only one of the included studies was conducted outside Italy, and the Italian studies only included white women, the generalisability of findings is limited.
d. Downgraded (‐1) for serious limitations in study design: all studies were at high risk of performance bias; one study was at high risk of detection bias.
e. Downgraded (‐1) for serious imprecision; evidence of imprecision with wide confidence intervals crossing the line of no effect.
f. Downgraded (‐1) for serious limitations in study design: all studies were at high risk of performance bias; two studies were at high risk of detection bias.
g. Downgraded (‐1) for serious limitations in study design: all studies were at high risk of performance bias. One study was at high risk of detection bias, and insufficient evidence to judge detection bias and subsequent judgement of unclear risk of bias. Due to insufficient evidence to judge allocation concealment in two studies and subsequent judgement of unclear risk of bias. Due to insufficient evidence to judge attrition bias in two studies and subsequent judgement of unclear risk of bias.
h. Downgraded (‐1) for serious limitations in study design: the study was at high risk of performance bias and detection bias for lack of blinding.
i. Downgraded (‐1) for serious Indirectness: only one study conducted in Ireland reported this outcome.
j. Downgraded (‐1) for serious imprecision: wide confidence intervals with very low event rates.