for the main comparison.
| Calcium supplementation compared with placebo for preventing hypertensive disorders and related problems in pregnancy | ||||||
|
Patient or population: pregnant women Settings: outpatient Intervention: high‐dose calcium (≥ 1 g/day) Comparison: placebo | ||||||
| Outcomes | Illustrative comparative risks* (95% CI) | Relative effect (95% CI) | No of participants (studies) | Quality of the evidence (GRADE) | Comments | |
| Assumed risk | Corresponding risk | |||||
| No calcium | Calcium | |||||
| Pre‐eclampsia | Overall |
RR 0.45 (0.31 to 0.65) RR 0.36 (0.20 to 0.65) RR 0.22 (0.12 to 0.42) |
15,730
(13) 10,678 (8) 587 (5) |
⊕⊕⊝⊝
low1 ⊕⊕⊝⊝ low1 ⊕⊕⊝⊝ low1 |
||
| 65 per 1000 | 29 per 1000 (20 to 42) | |||||
| Low‐calcium diet | ||||||
| 57 per 1000 | 21 per 1000 (11 to 37) | |||||
| High‐risk women | ||||||
| 176 per 1000 | 38 per 1000 (21 to 74) | |||||
| Preterm birth | Overall | RR 0.76 (0.60 to 0.97) | 15,275 (11) | ⊕⊕⊝⊝ low1 | ||
| 104 per 1000 | 79 per 1000 (62 to 101) | |||||
| HELLP syndrome | 1 per 1000 | 3 per 1000 | RR 2.67 (1.05 to 6.82) | 12,901 (2) |
⊕⊕⊕⊕ high | |
| GRADE Working Group grades of evidence High quality: Further research is very unlikely to change our confidence in the estimate of effect. Moderate quality: Further research is likely to have an important impact on our confidence in the estimate of effect and may change the estimate. Low quality: Further research is very likely to have an important impact on our confidence in the estimate of effect and is likely to change the estimate. Very low quality: We are very uncertain about the estimate. | ||||||
1 Downgraded two levels due to heterogeneity and small study effects (‐2)
CI: confidence interval HELLP: haemolysis, elevated liver enzymes and low platelets RR: risk ratio