Table 1. Characteristics of the study population, according to the mode of infant feeding at age 3 months.
| Formula-fed | Mixed-fed | Breastfed | |
| N | 88 | 91 | 137 |
| Boys (n, %) | 48 (55%) | 49 (54%) | 74 (54%) |
| Age at 3mo exam (mo) | 3.2 (0.3) | 3.2 (0.3) | 3.2 (0.4) |
| Firstborn (n, %) | 43 (49%) | 45 (49%) | 67 (49%) |
| Birth weight (SDS) | 0.0 (1.1) | −0.1 (0.9) | 0.0 (0.9) |
| Gestational age (wk) | 39.9 (1.4) | 39.8 (1.6) | 40.2 (1.2) |
| Maternal BMI (kg/m2) | 25.1 (4.4) | 23.7 (3.4) | 23.1 (3.6) |
| Maternal age (years) | 32.5 (4.4) | 34.0 (3.9) | 33.2 (4.8) |
| Index of Multiple Deprivation 2007 | 10.1 (4.2) | 8.8 (3.3) | 9.8 (3.8) |
| Maternal Qualification (n, %) | |||
| *Missing | 49 (56%) | 46 (51%) | 85 (62%) |
| O-level, vocational, other | 11 (13%) | 5 (5%) | 4 (3%) |
| A-level, Certificate, Diploma | 12 (14%) | 7 (8%) | 7 (5%) |
| Degree level or higher | 16 (18%) | 33 (36%) | 41 (30%) |
Data are mean (SD) or n (%).
*35 mothers did not complete the relevant prenatal questionnaire and 145 did not complete this question.