Table 1 Characteristics of available data sets: Mean (SD) or N (%) for every variable

Sample size

426

264

486

149

795

139

Gestational age (weeks)

40.04 (1.55)

12.79 (0.82)

39.99 (1.60)

39.87 (1.42)

39.74 (1.67)

39.89 (1.43)

Maternal alcohol use, yes^c

40 (10)

24 (14)

48 (10)

16 (12)

115 (17)

17 (14)

Maternal smoking, yes^a,b

18 (4)

29 (11)

20 (4)

13 (9)

32 (4)

13 (9)

Maternal mental disorders, yes

46 (11)

26 (9)

55 (11)

20 (14)

63 (8)

18 (13)

Maternal diabetes, yes^{a, c}

93 (22)

57 (22)

105 (22)

26 (17)

222 (28)

20 (14)

Maternal hypertensive disorder, yes^{a, b, c}

26 (6)

23 (9)

28 (6)

36 (24)

272 (34)

33 (24)

Maternal BMI^{a, b, c}

23.94 (4.21)

24.20 (4.27)

23.82 (4.16)

25.23 (5.76)

27.38 (6.30)

24.85 (5.79)

Maternal age (years)^{a, b, c}

34.70 (4.81)

34.96 (5.75)

34.59 (4.86)

32.13 (5.00)

33.33 (5.74)

32.04 (5.17)

Multiparous, yes^{b, c}

193 (45)

153 (58)

235 (48)

85 (57)

558 (71)

74 (53)

Induced labor, yes

114 (27)

66 (25)

125 (26)

37 (25)

240 (30)

31 (22)

Delivery mode, aided^a

129 (30)

87 (33)

145 (30)

51 (35)

233 (30)

55 (40)

Head circumference (cm)

35.10 (1.52)

35.04 (1.73)

35.07 (1.62)

35.21 (1.36)

35.13 (2.15)

35.19 (1.34)

Birth length (cm)^{a, b}

50.23 (2.20)

50.13 (2.24)

50.17 (2.40)

49.77 (2.48)

50.21 (2.44)

49.65 (2.53)

Birth weight (g)^a

3532 (489)

3489 (526)

3534 (509)

3454 (519)

3546 (559)

3425 (523)

Child sex, female

210 (49)

124 (47)

238 (49)

73 (49)

372 (47)

72 (52)