Table 1 Characteristics of the study participants.

Maternal characteristics

Maternal age (years, median (IQR))

28 (26, 31)

BMI (kg/m², mean ± SD)

21.5 ± 2.9

GWG (kg, mean ± SD)^a

9.1 ± 3.6

Han ethnicity (%)

98.7

Marital status (%)

97.9

Primiparity (%)

77.5

History of miscarriage or abortion (%)

47.3

Smoking or drinking during pregnancy (%)

0.4

Chinese BMI category (%)

Underweight

11.9

Normal weight

71.2

Overweight

14.0

Obese

2.9

Asian BMI category (%)

Underweight

11.9

Normal weight

63.4

Overweight

21.1

Obese

3.6

WHO BMI category (%)

Underweight

11.9

Normal weight

76.9

Overweight

9.9

Obese

1.3

Neonatal characteristics

Gestational age at delivery (week, mean ± SD)

39.4 ± 1.5

Birth weight (g, mean ± SD)^b

3310.7 ± 436.9

Birth length (cm, mean ± SD)^c

49.7 ± 1.9

Apgar score at 1 min (median (IQR))

10 (9, 10)

Apgar score at 5 min (median (IQR))

10 (10, 10)

New born sex (n, %)^d

Male

663 (52.2)

Female

608 (47.8)

Infant characteristics

BSID test^e

MDI (mean ± SD)

94.6 ± 17.6

PDI (mean ± SD)

87.0 ± 14.6