Table 3. Changes in Z scores for body weight, body length and weight for length from birth to months 3, 6, 9, and 12 according to pre-pregnancy BMI and gestational weight gain categories.
| Pre-pregnancy BMI (kg/m2) |
P for trend | IOM categories#§ |
P for trend | ||||||
|---|---|---|---|---|---|---|---|---|---|
| <18.5 | 18.5-23.99 | 24.0-27.99 | ≥28.0 | Inadequate | Adequate | Excessive | |||
| From months 0 to 3 | |||||||||
| No. of subjects | 3 331 | 19 161 | 5 371 | 1 696 | 2 808 | 9 714 | 17 037 | ||
| Weight-for-age | |||||||||
| Model 1* | 0.93 (0.02) | 0.88 (0.01) | 0.76 (0.01) | 0.57 (0.02) | <0.001 | 0.99 (0.02) | 0.92 (0.01) | 0.78 (0.01) | <0.001 |
| Model 2† | 0.72 (0.01) | 0.86 (0.01) | 0.87 (0.01) | 0.82 (0.02) | <0.001 | 0.84 (0.02) | 0.85 (0.01) | 0.84 (0.01) | 0.890 |
| Length-for-age | |||||||||
| Model 1* | 0.97 (0.02) | 0.93 (0.01) | 0.85 (0.02) | 0.72 (0.03) | <0.001 | 0.90 (0.02) | 0.92 (0.01) | 0.90 (0.01) | 0.188 |
| Model 2† | 0.84 (0.02) | 0.92 (0.01) | 0.91 (0.01) | 0.87 (0.02) | <0.001 | 0.82 (0.02) | 0.88 (0.01) | 0.93 (0.01) | <0.001 |
| Weight-for-length | |||||||||
| Model 1* | 0.50 (0.02) | 0.41 (0.01) | 0.32 (0.02) | 0.14 (0.03) | <0.001 | 0.61 (0.02) | 0.49 (0.01) | 0.30 (0.01) | <0.001 |
| Model 2† | 0.21 (0.02) | 0.39 (0.01) | 0.47 (0.01) | 0.48 (0.03) | <0.001 | 0.41 (0.02) | 0.39 (0.01) | 0.39 (0.01) | 0.730 |
| From months 3 to 6 | |||||||||
| No. of subjects | 3 177 | 18 214 | 5 090 | 1 625 | 2 654 | 9 218 | 16 234 | ||
| Weight-for-age | |||||||||
| Model 1* | 0.13 (0.01) | 0.15 (0.004) | 0.18 (0.01) | 0.23 (0.01) | <0.001 | 0.19 (0.01) | 0.17 (0.01) | 0.14 (0.01) | <0.001 |
| Model 2† | 0.11 (0.01) | 0.15 (0.004) | 0.19 (0.01) | 0.25 (0.01) | <0.001 | 0.17 (0.01) | 0.17 (0.01) | 0.15 (0.01) | 0.037 |
| Length-for-age | |||||||||
| Model 1* | 0.06 (0.02) | 0.09 (0.01) | 0.12 (0.01) | 0.11 (0.02) | 0.017 | 0.11 (0.02) | 0.10 (0.01) | 0.08 (0.01) | 0.084 |
| Model 2† | 0.05 (0.02) | 0.09 (0.01) | 0.12 (0.01) | 0.12 (0.02) | 0.002 | 0.11 (0.02) | 0.10 (0.01) | 0.08 (0.01) | 0.210 |
| Weight-for-length | |||||||||
| Model 1* | 0.29 (0.02) | 0.32 (0.01) | 0.34 (0.01) | 0.41 (0.02) | <0.001 | 0.33 (0.02) | 0.33 (0.01) | 0.32 (0.01) | 0.381 |
| Model 2† | 0.30 (0.02) | 0.32 (0.01) | 0.33 (0.01) | 0.40 (0.02) | 0.003 | 0.33 (0.02) | 0.34 (0.01) | 0.31 (0.01) | 0.189 |
| From months 6 to 12 | |||||||||
| No. of subjects | 3 046 | 17 354 | 4 873 | 1 557 | 2 559 | 8 755 | 15 516 | ||
| Weight-for-age | |||||||||
| Model 1* | -0.06 (0.01) | -0.09 (0.01) | -0.07 (0.01) | -0.06 (0.02) | 0.027 | -0.10 (0.01) | -0.08 (0.01) | -0.08 (0.01) | 0.162 |
| Model 2† | -0.08 (0.01) | -0.09 (0.01) | -0.06 (0.01) | -0.03 (0.02) | 0.001 | -0.12 (0.01) | -0.08 (0.01) | -0.07 (0.01) | 0.002 |
| Length-for-age | |||||||||
| Model 1* | -0.24 (0.02) | -0.23 (0.01) | -0.20 (0.01) | -0.16 (0.02) | 0.002 | -0.19 (0.02) | -0.20 (0.01) | -0.23 (0.01) | 0.008 |
| Model 2† | -0.25 (0.02) | -0.23 (0.01) | -0.19 (0.01) | -0.14 (0.02) | <0.001 | -0.19 (0.02) | -0.21 (0.01) | -0.23 (0.01) | 0.050 |
| Weight-for-length | |||||||||
| Model 1* | 0.09 (0.02) | 0.07 (0.01) | 0.08 (0.01) | 0.08 (0.02) | 0.418 | 0.01 (0.02) | 0.06 (0.01) | 0.09 (0.01) | <0.001 |
| Model 2† | 0.10 (0.02) | 0.07 (0.01) | 0.08 (0.01) | 0.08 (0.02) | 0.366 | 0.01 (0.02) | 0.07 (0.01) | 0.09 (0.01) | <0.001 |
| From months 0 to 12 | |||||||||
| No. of subjects | 3 181 | 18 206 | 5 124 | 1 627 | 2 686 | 9 178 | 16 274 | ||
| Weight-for-age | |||||||||
| Model 1* | 1.00 (0.02) | 0.93 (0.01) | 0.88 (0.02) | 0.73 (0.03) | <0.001 | 1.09 (0.02) | 1.01 (0.01) | 0.84 (0.01) | <0.001 |
| Model 2† | 0.75 (0.02) | 0.91 (0.01) | 1.01 (0.01) | 1.03 (0.02) | <0.001 | 0.90 (0.02) | 0.92 (0.01) | 0.92 (0.01) | 0.395 |
| Length-for-age | |||||||||
| Model 1* | 0.80 (0.02) | 0.79 (0.01) | 0.78 (0.02) | 0.66 (0.03) | <0.001 | 0.83 (0.02) | 0.83 (0.01) | 0.75 (0.01) | <0.001 |
| Model 2† | 0.66 (0.02) | 0.78 (0.01) | 0.85 (0.01) | 0.84 (0.02) | <0.001 | 0.74 (0.02) | 0.78 (0.01) | 0.80 (0.01) | 0.030 |
| Weight-for-length | |||||||||
| Model 1* | 0.88 (0.02) | 0.79 (0.01) | 0.74 (0.02) | 0.61 (0.03) | <0.001 | 0.96 (0.02) | 0.88 (0.01) | 0.70 (0.01) | <0.001 |
| Model 2† | 0.60 (0.02) | 0.77 (0.01) | 0.88 (0.01) | 0.93 (0.02) | <0.001 | 0.75 (0.02) | 0.78 (0.01) | 0.80 (0.01) | 0.216 |
Data are means (SE).
* Model 1 was adjusted for maternal age, maternal height, maternal gestational diabetes, maternal education, smoking, family income, maternal occupation, and mode of infant feeding.
† Model 2 adjusted for above variables and also birth weight for gestational age Z-score in change weight-for-age Z-score, birth length for gestational age Z-score in change length-for-age Z-score, and birth weight for birth length Z-score in change weight-for-length Z-score.
# Adjusted also for prepregnancy BMI.
§ IOM categories: Inadequate (1): <12.5 kg (pre-pregnancy BMI <18.5 kg/m2), <11.5 kg (BMI 18.5- 23.9 kg/m2), <7 kg (BMI 24.0–27.9 kg/m2), and <5 kg (BMI >28 kg/m2); Adequate (1): 12.5–18 kg (BMI <18.5 kg/m2), 11.5–16 kg (BMI 18.5- 23.9 kg/m2), 7–11.5 kg (BMI 24.0–27.9 kg/m2), and 5–9 kg (BMI >28 kg/m2); Excessive (1): >18 kg (BMI <18.5 kg/m2), >16 kg (BMI 18.5- 23.9 kg/m2), >11.5 kg (BMI 24.0–27.9 kg/m2), and >9 kg (BMI >28 kg/m2), according to the Chinese maternal pre-pregnancy BMI classification standard and the 2009 IOM GWG recommendations.