Table 1 Characteristics of the study population

Maternal age, years

28.06 ± 4.87

28.54 ± 3.68

Maternal BMI, kg/m²

23.08 ± 3.73

23.61 ± 3.70

Maternal educational level, No(%)

 High school or lower

13(76.5%)

45(65.2%)

 College or higher

4(23.5%)

24(34.8%)

Maternal parity

 Primiparous

15(88.2%)

65(94.2%)

 ≥ 1 child

2(11.8%)

4(5.8%)

Paternal age, years

29.06 ± 4.29

29.37 ± 4.07

Paternal BMI, kg/m²

24.91 ± 3.39

25.34 ± 4.19

Paternal educational level, No(%)

 High school or lower

13(76.5)%)

46(66.7%)

 College or higher

4(23.5%)

23(33.3%)

Smoking, No (%)

 NO

11(64.7%)

47(68.1%)

 Yes

6(35.3%)

22(31.9%)

Child age, years

4.59 ± 1.12

4.19 ± 1.18

Child BMI, kg/m²

16.70 ± 3.22

16.59 ± 1.81

Child female sex, n(%)

14(82.4%)

49(71.0%)

Child twin or not, n(%)

 Singleton

16(94.1%)

52(75.4%)

 Twin

1(5.9%)

17(24.6%)

Child gestational age, n(%)

 < 37 weeks (preterm)

2(11.8%)

6(8.7%)

 37–42 weeks (full-term)

14(82.4%)

61(88.4%)

 > 42 weeks (post-term)

1(5.9%)

2(2.9%)

Child birthweight, kg

3.51 ± 0.68

3.28 ± 0.68