Table 3.
Equations for generation of smoothed curves of BMI percentiles during pregnancy for all women and according to initial BMI.
| Weight Gain | Percentile | Intercept | Slope X GA | R2 of model | BMI (kg/m2) of percentile example for GA (weeks) | |||||
|---|---|---|---|---|---|---|---|---|---|---|
| 12 | 20 | 28 | ||||||||
| Any Initial BMI | ||||||||||
| Adequate Gain | P 5 | = | 16.8 | + | 0.147 | X GA | 0.90 | 18.6 | 19.7 | 20.9 |
| P 10 | = | 17.4 | + | 0.168 | X GA | 0.96 | 19.4 | 20.8 | 22.1 | |
| P 50 | = | 22.9 | + | 0.155 | X GA | 0.93 | 24.8 | 26.0 | 27.2 | |
| P 85 | = | 28.8 | + | 0.151 | X GA | 0.79 | 30.6 | 31.8 | 33.0 | |
| Excessive Gain | P 90 | = | 31.3 | + | 0.134 | X GA | 0.62 | 32.9 | 34.0 | 35.1 |
| P 95 | = | 34.3 | + | 0.122 | X GA | 0.80 | 35.8 | 36.7 | 37.7 | |
| Low Weight (Initial BMI <18.5 kg/m2) | ||||||||||
| Adequate Gain | P 5 | = | 15.1 | + | 0.110 | X GA | 0.57 | 16.4 | 17.3 | 18.2 |
| P 10 | = | 14.8 | + | 0.133 | X GA | 0.73 | 16.4 | 17.5 | 18.5 | |
| P 50 | = | 16.2 | + | 0.156 | X GA | 0.93 | 18.1 | 19.3 | 20.6 | |
| P 85 | = | 16.1 | + | 0.212 | X GA | 0.93 | 18.6 | 20.3 | 22.0 | |
| Excessive Gain | P 90 | = | 16.5 | + | 0.207 | X GA | 0.85 | 19.0 | 20.6 | 22.3 |
| P 95 | = | 16.1 | + | 0.240 | X GA | 0.83 | 19.0 | 20.9 | 22.8 | |
| Adequate Weight (18.5 ≤ Initial BMI <25 kg/m2) | ||||||||||
| Adequate gain | P 5 | = | 17.2 | + | 0.145 | X GA | 0.93 | 18.9 | 20.1 | 21.3 |
| P 10 | = | 17.4 | + | 0.163 | X GA | 0.96 | 19.4 | 20.7 | 22.0 | |
| P 50 | = | 20.2 | + | 0.167 | X GA | 0.93 | 22.2 | 23.5 | 24.9 | |
| P 85 | = | 22.1 | + | 0.178 | X GA | 0.94 | 24.2 | 25.7 | 27.1 | |
| Excessive Gain | P 90 | = | 22.3 | + | 0.190 | X GA | 0.95 | 24.6 | 26.1 | 27.6 |
| P 95 | = | 22.6 | + | 0.207 | X GA | 0.95 | 25.1 | 26.7 | 28.4 | |
| Overweight (25 ≤ Initial BMI <30 kg/m2) | ||||||||||
| Adequate Gain | P 5 | = | 23.8 | + | 0.090 | X GA | 0.85 | 24.9 | 25.6 | 26.3 |
| P 10 | = | 24.0 | + | 0.106 | X GA | 0.92 | 25.3 | 26.1 | 27.0 | |
| P 50 | = | 24.9 | + | 0.159 | X GA | 0.94 | 26.8 | 28.1 | 29.4 | |
| P 85 | = | 26.6 | + | 0.183 | X GA | 0.93 | 28.8 | 30.3 | 31.7 | |
| Excessive Gain | P 90 | = | 27.0 | + | 0.186 | X GA | 0.94 | 29.2 | 30.7 | 32.2 |
| P 95 | = | 27.0 | + | 0.214 | X GA | 0.93 | 29.6 | 31.3 | 33.0 | |
| Obese (Initial BMI ≥30 kg/m2) | ||||||||||
| Adequate Gain | P 5 | = | 30.0 | + | 0.040 | X GA | 0.35 | 30.5 | 30.8 | 31.1 |
| P 10 | = | 30.3 | + | 0.070 | X GA | 0.55 | 31.1 | 31.7 | 32.3 | |
| P 50 | = | 32.8 | + | 0.115 | X GA | 0.72 | 34.2 | 35.1 | 36.0 | |
| P 85 | = | 37.9 | + | 0.070 | X GA | 0.14 | 38.7 | 39.3 | 39.9 | |
| Excessive Gain | P 90 | = | 39.0 | + | 0.061 | X GA | 0.09 | 39.7 | 40.2 | 40.7 |
| P 95 | = | 40.6 | + | 0.079 | X GA | 0.12 | 41.5 | 42.2 | 42.8 | |
GA = gestational age, BMI = body mass index.
P = percentile, R2 = determination coefficient.
Weight gain: underweight = any BMI value lower than P5; Obesity = any BMI value greater than P95.