Characteristics of study women completing questionnaires by randomisation status
| Vitamins (n=330) | Placebo (n=313) | Comparison (99% CI) | |
| Mean (SD) maternal age (years) | 32.2 (5.1) | 32.0 (5.2) | 0.2 (−0.9 to 1.2) |
| Mean (SD) BMI (kg/m2) | 29.3 (6.7) | 29.3 (6.8) | −0.04 (−1.4 to 1.3) |
| Ethnicity (non-white) | 12% | 11% | 1.10 (0.58 to 2.10) |
| Primiparity | 52% | 52% | 1.00 (0.67 to 1.50) |
| Multiple pregnancy* | 17% | 17% | 0.96 (0.56 to 1.64) |
| In work (including self-employed and maternity leave) | 80% | 75% | 1.33 (0.82 to 2.17) |
| Smoking status | |||
| Never | 60% | 61% | |
| Current smoker ≥1/day | 9% | 7% | 1.25 (0.59 to 2.68) |
| Stopped before present pregnancy | 24% | 24% | 1.04 (0.63 to 1.569) |
| Stopped during pregnancy | 7% | 8% | 0.81 (0.37 to 1.79) |
| Compliance with trial medication (took at least 80%) | 77% | 76% | 1.02 (0.63 to 1.65) |
Results shown are mean (SD) or percentages as appropriate.
Comparisons are differences in means or ORs as appropriate with 99% CIs.
↵* Includes three mothers of triplets (one in vitamin group, two in placebo group).
BMI, body mass index.