Table 1 Characteristics of women in the study sample and comparison between groups

Maternal Data

Age at delivery

n = 2,460

n = 2,484

mean (SD)

31.2 (6.8)

27.3 (7.0)

t(df)

19.9 (4942)*

Parity

n = 2,440

n = 2,475

Nulliparous

40.6%

41.6%

Multiparous

59.4%

58.4%

χ2 (df)

0.5 (1)

BMI

n = 1,690

N = 1,489

mean (SD)

33.8 (0.2)

25.7 (0.1)

t(df)

34.1 (3177)*

SIMD quintile

n = 2,181

n = 2,237

1 (most deprived)

28.6%

24.5%

2

22.4%

20.8%

3

17.7%

20.9%

4

16.1%

17.2%

5 (least deprived)

15.4%

16.6%

χ2 (df)

15.8 (4)*

Newborn Data

Birth weight in grams

n = 1,996

n = 2,482

mean (SD)

3421 (588)

3417 (501.5)

t(df)

0.3 (4476)

Gestational age (weeks)

n = 1,695

n = 2,016

mean (SD)

38.3 (2.1)

39.8 (1.8)

t(df)

19.8 (4942)*

Gender (%)

n = 1,996

n = 2,484

Male

52.9%

51.6%

Female

47.1%

48.4%

χ2 (df)

0.7 (1)

Baby APGAR

n = 1,962

2,376

0–7

3.7%

1.6%

8–10

96.3%

98.4%

χ2 (df)

19.4 (1)*