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. Author manuscript; available in PMC: 2017 Apr 1.
Published in final edited form as: Twin Res Hum Genet. 2016 Apr;19(2):112–124. doi: 10.1017/thg.2016.11

Table 5.

Number of twin individuals, mean and standard deviation of birth weight (kg) and BMI (kg/m2) by birth order, age and sex in dizygotic twins

Birth order Men
Women
N Mean p valuea SD p valueb N Mean p valuea SD p valueb
Age 1 1 5088 17.20 <0.001 1.39 0.037 4759 16.81 0.004 1.35 0.728
2 4962 17.04 1.34 4821 16.67 1.35
Age 2 1 4184 16.57 <0.001 1.41 0.930 3815 16.20 0.006 1.38 0.423
2 4102 16.40 1.40 3871 16.04 1.39
Age 3 1 5407 16.03 0.003 1.54 0.003 5085 15.74 0.010 1.53 0.314
2 5266 15.84 1.47 5208 15.63 1.57
Age 4 1 2993 16.01 0.047 1.87 0.808 2818 15.81 0.044 1.89 0.656
2 2954 15.82 1.89 2848 15.68 1.93
Age 5 1 2349 15.33 0.020 1.59 0.806 2099 15.24 0.049 1.68 0.195
2 2259 15.17 1.60 2189 15.09 1.71
Age 6 1 583 15.65 0.867 2.02 0.153 455 15.65 0.164 2.29 0.574
2 552 15.59 2.21 469 15.40 2.22
Age 7 1 3986 15.50 0.018 1.85 0.077 3877 15.59 0.178 2.09 0.144
2 3981 15.35 1.92 3864 15.41 2.03
Age 8 1 1478 15.75 0.296 2.09 0.625 1279 15.96 0.194 2.26 0.953
2 1433 15.63 2.04 1318 15.76 2.26
Age 9 1 1445 16.61 0.660 2.61 0.161 1354 16.77 0.181 2.80 0.765
2 1449 16.41 2.49 1316 16.58 2.82
Age 10 1 3171 16.70 0.060 2.43 0.002 2994 16.98 0.107 2.58 0.422
2 3148 16.48 2.32 2973 16.77 2.68
Age 11 1 2385 17.56 0.326 2.77 0.992 2146 17.77 0.710 3.01 0.465
2 2288 17.40 2.80 2153 17.65 3.04
Age 12 1 3152 18.06 0.237 2.99 0.853 3031 18.26 0.294 3.05 0.391
2 3021 17.89 2.99 3048 18.02 3.02
Age 13 1 1035 18.59 0.875 3.25 0.572 898 18.95 0.853 3.35 0.876
2 965 18.52 3.20 896 18.85 3.35
Age 14 1 2353 19.58 0.315 3.24 0.741 2332 19.92 0.339 3.16 0.539
2 2266 19.58 3.16 2370 19.70 3.11
Age 15 1 1143 20.03 0.106 3.28 0.007 1042 20.23 0.898 3.26 0.911
2 1078 19.62 2.90 1013 20.24 3.37
Age 16 1 1990 20.87 0.290 3.03 0.800 2086 21.05 0.109 3.34 0.046
2 1940 20.77 3.01 2090 20.75 3.11
Age 17 1 2159 21.39 0.644 2.85 0.038 2230 21.09 0.158 2.98 0.500
2 2092 21.30 3.04 2224 20.79 2.93
Age 18 1 1680 21.79 0.597 2.86 0.012 1281 21.29 0.148 3.02 0.024
2 1614 21.83 3.01 1320 20.93 2.76
Age 19 1 1044 21.91 0.785 2.61 0.969 1099 21.38 0.212 3.05 0.082
2 1049 21.83 2.67 1047 21.12 2.84
Age 20–29 1 4036 23.39 0.398 3.04 0.507 4398 22.07 0.171 3.58 0.040
2 4121 23.37 3.11 4270 21.82 3.42
Age 30–39 1 3221 24.81 0.813 3.42 0.987 4120 23.19 0.619 4.30 0.125
2 3351 24.75 3.41 3887 23.02 4.17
Age 40–49 1 2403 25.48 0.932 3.35 0.553 2877 24.07 0.929 4.23 0.975
2 2411 25.39 3.40 2775 23.99 4.25
Age 50–59 1 2678 25.69 0.970 3.35 0.673 3261 24.75 0.525 4.00 0.065
2 2634 25.63 3.28 3086 24.53 3.89
Age 60–69 1 1265 25.49 0.897 3.19 0.595 1560 25.15 0.769 4.19 0.373
2 1276 25.64 3.29 1532 25.07 4.09
Age 70–79 1 310 25.34 0.909 3.35 0.279 435 24.99 0.905 3.86 0.610
2 329 25.31 3.20 390 24.87 4.03

p valuea: p value for equality of means, p valueb: p value for equality of variances, SD: standard deviation.