Table 2. Change in mean BMI (kg m−2) among parous women by parity and total duration of breastfeeding in models variously standardised.
| Number of women | Unadjusted results | Model A—standardised by age and region only | Model A + additionally standardised by breastfeeding (when looking at parity), and for parity (when looking at breastfeeding) | Model A + additionally standardised by breastfeeding, parity, socioeconomic group, smoking and physical activity | |
|---|---|---|---|---|---|
| Parity (mean) | |||||
| 1 | 100 639 | Reference | Reference | Reference | Reference |
| 2 | 310 841 | −0.02 (−0.05 to 0.01) | −0.01 (−0.04 to 0.02) | 0.11 (0.08 to 0.14) | 0.13 (0.09 to 0.16) |
| 3 | 159 100 | 0.45 (0.41 to 0.48) | 0.45 (0.41 to 0.48) | 0.63 (0.60 to 0.67) | 0.58 (0.55 to 0.62) |
| ⩾4 (4.4) | 80 600 | 1.31 (1.27 to 1.36) | 1.30 (1.26 to 1.34) | 1.53 (1.49 to 1.58) | 1.33 (1.28 to 1.37) |
| Total duration of breastfeeding (mean in months) | |||||
| Did not breastfeed | 201 688 | Reference | Reference | Reference | Reference |
| <6 months (2.3) | 239 836 | −0.27 (−0.24 to −0.30) | −0.26 (−0.24 to −0.29) | −0.32 (−0.29 to −0.35) | −0.24 (−0.21 to −0.26) |
| 6–9 months (7.3) | 82 198 | −0.43 (−0.40 to −0.47) | −0.42 (−0.38 to −0.46) | −0.52 (−0.48 to −0.56) | −0.36 (−0.32 to −0.40) |
| ⩾10 months (18.5) | 127 458 | −0.44 (−0.41 to −0.48) | −0.43 (−0.40 to −0.46) | −0.75 (−0.71 to −0.78) | −0.53 (−0.50 to −0.57) |
| Change in mean BMI per 6 months breastfeedinga | −0.12 (−0.11 to −0.13) | −0.11 (−0.10 to 0.12) | −0.17 (−0.16 to −0.18) | −0.13 (−0.11 to −0.13) | |
Abbreviation: BMI, body mass index.
a
Trend fitted through category mid-points and multiplied as appropriate.