Table 1 Characteristics of participants (n = 2405)

Maternal age, years

26.21 ± 3.32

26.81 ± 3.70

3.95

0.000

Pre-pregnancy BMI^a

20.50 ± 2.73

20.62 ± 2.78

1.01

0.311

Gestational weight gain^a

18.13 ± 5.01

17.55 ± 5.07

−2.55

0.011

Maternal education

11.20

0.011

 Bachelor degree or above

163(22.9)

478(28.3)

 Junior college

217(30.4)

536(31.7)

 Senior high school or equal

182(25.5)

360(21.3)

 Junior high school or below

151(21.2)

318(18.8)

Family monthly income

5.74

0.057

  < 2500 RMB

222(31.2)

448(26.5)

 2500–4000 RMB

294(41.2)

726(42.9)

  > 4000 RMB

197(27.6)

518(30.6)

Maternal smoking

10.45

0.001

 Never

670(94.0)

1638(96.8)

 Former/current

43(6.0)

54(3.2)

Maternal drinking

1.20

0.274

 Never

651(91.3)

1567(92.6)

 Occasionally/frequently

62(8.7)

125(7.4)

Gestational diabetes

80(11.2)

215(12.7)

2.73

0.435

Pregnancy-induced hypertension^a

28(3.9)

72(4.3)

2.20

0.532

Preterm birth

17(2.4)

58(3.4)

1.81

0.179

Low birth weight^a

12(1.7)

34(2.0)

0.37

0.831

Cesarean^a

389(2.4)

819(3.4)

7.83

0.005

Boys

360

874

2.27

0.602

Exclusive breastfeeding at first 6 months^a

59(8.5)

215(13.0)

9.64

0.002