Table 1: Maternal characteristics divided into three groups based on the criteria of infant birth weight in Japan.
Top row, n(%); second row, the expected value
The data of GWD and GWG were shown using mean±SD
n Categpries of infant birth weight (g) P-value
LBW<2500
n=170
n (%)		 Normal BW
n=2357
n (%)		 Macrosomia>4000
n=24
n (%)
Maternal age (Years) <30

30-34

35-39

≥40
 468

1047

708

328
 34(1.3%)
31.2
61(2.4%)
69.8
46(1.8%)
47.2
29(1.1%)
21.9		 432(16.9%)
432.4
981(38.5%)
967.4
649(25.4%)
654.2
295(11.6%)
303.1		 2(0.1%)
4.4
5(0.2%)
9.9
13(0.5%)
6.7
4(0.2%)
3.1		 p<0.05
Pre-pregnancy BMI (kg/m2) <18.5

18.5-24.9

≥25

 567

1851

133

 49(1.9%)
37.8
112(4.4%)
123.4
9(0.4%)
8.9		 515(20.2%)
523.9
1722(67.5%)
1710.2
120(4.7%)
122.9		 3(0.1%)
5.3
17(0.6%)
17.4
4(2.0)
1.3		 p<0.05
Pre-pregnancy BMI/ MHLW weight gain guidelines <18.5 (underweight)
Below

Within

Above
165

229

173
24(4.2%)
14.3
16(2.8%)
19.8
9(1.6%)
15.0
141(24.9%)
149.9
213(37.6%)
208.0
161(28.4%)
157.1
0(0.0%)
0.9
0(0.0%)
1.2
3(0.5%)
0.9		 p<0.01
18.5-25.0 (Average)
Below

Within

Above
265

1110

476
38 (2.1%)
16.0
62 (3.4%)
67.2
12 (0.6%)
28.8
226 (12.2%)
246.5
1038 (56.1%)
1032.6
458 (24.7%)
442.8
1 (0.1%)
2.4
10 (0.5%)
10.2
6 (0.3%)
4.4		 P<0.001
≥25 (Overweight)
Below

Within

Above
9

32

92
1 (0.7%)
0.6
4(3.0%)
2.2
4(3.0%)
6.2
8(6.0%)
8.1
28(21.1%)
28.9
84(63.2%)
83.0
0(0.0%)
0.3
0(0.0%)
1.0
4(3.0%)
2.8		 ns
Parity primiparas

multiparas
 1580

971
 116 (4.6%)
105.3
54(2.1%)
64.7		 1454(57.0%)
1459.8
903(35.4%)
897.2		 10(0.4%)
14.9
14(0.5%)
9.1		 p<0.05
Infant gender male

female
 1307

1244
 67 (2.6%)
87.1
103(4.0%)
82.9		 1226(48.1%)
12707.6
1131(44.4%)
1149.4		 14(0.5%)
12.3
10(0.4%)
11.9		 P<0.001
Mean±SD
Gestational week at delivery (GWD) (weeks) 37.9±1.3 39.3±1.1 40.4±0.8 P<0.001
Gestational weight gain (GWG) (kg) 8.1±3.8 10.3±3.5 12.0±3.9 P<0.001