Methodological quality of the studies included in the review
| Study | Sample size estimate | Method of randomisation | AllocationConcealment | Blinding of intervention | Proportion (%) included in analysis* | Blinding of outcome | Baseline variables compared | Assessment of confounding |
|---|---|---|---|---|---|---|---|---|
| *This is the percentage included in the analysis after excluding losses to follow-up (for which there were very few for the short-term outcomes) and those with missing values for some outcomes. | ||||||||
| Davies9 | No | Randomised but method not stated | Not stated | Not stated | 100% | Not stated | Yes | Stratification by gestational age |
| Raiha et al10 | No | Blocked randomisation | Coding of bottles | Not stated | 95% | Not stated | Yes | Stratification by gestational age |
| Schultz et al11 | No | Randomised but method not stated | Not stated | Not stated | 100% | Not stated | Yes | No |
| Gross12 | No | Random number table | Not stated | Not stated | 100% | Not stated | Yes | No |
| Lucas et al13–22 | Yes | Blocked randomisation | Opaque, sealed, numbered envelopes | No | 100% for short term outcomes69% at 9 months 86% at 18 months 82% at 8 years | For some outcomes | Yes | For some outcomes |
| Cooper et al23 | No | Not random (alternating assignment) | Not stated | Not stated | 100% | Not stated | Yes | No |
| Putet et al24 | No | Not stated (may not be randomised) | Not stated | Not stated | 92% | Not stated | Yes | No |