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Table 2 Characteristics of the women in UK Biobank, ALSPAC, BiB and MoBa included in Mendelian randomization

From: Investigating causal relations between sleep duration and risks of adverse pregnancy and perinatal outcomes: linear and nonlinear Mendelian randomization analyses

Variable a

UK Biobank (N=176,897)

ALSPAC (N=6826)

BiB (N=2940)

MoBa (N=14,584)

 

Mean (standard deviation)

Maternal age (years)

25.5 (4.6) b

28.7(4.7)

26.8 (6.0)

30.0 (4.5)

Maternal height (cm)

162.5 (6.2)

164.3 (6.7)

164.4 (6.1)

168.4 (5.7)

Maternal body mass index (kg/m2)

27.0 (5.1)

22.9 (3.7)

26.7 (6.0)

24.0 (4.2)

Parity

2.2 (1.0)

0.8 (0.9)

0.8 (1.1)

0.7 (0.8)

Gestational age (weeks)

38.9 (3.8) c

39.6 (1.7)

39.7 (1.9)

39.6 (1.7)

Offspring birthweight (grams)

3186.7 (547.6)

3441.5 (523.0)

3357.9 (571.2)

3640.8 (513.4)

 

N (%)

Maternal education

 O levels/GCSEs or equivalent and below

81,113 (46.4)

4043 (59.5)

1400 (47.6)

252 (1.7)

 A levels/AS levels or equivalent

40,817 (23.3)

1719 (25.3)

485 (16.5)

4378 (30.0)

 College or university degree

53,062 (30.3)

1035 (15.2)

551 (18.7)

9100 (62.4)

Maternal ever smoking

74,308 (42.2)

1450 (21.6) d

911 (31.0) d

1106 (7.6) d

Maternal ever drinking

162,436 (92.0)

4580 (70.2) d

1793 (61.0) d

3644 (25.0) d

Offspring sex, male

Not available

3430 (50.2)

1504 (51.2)

7456 (51.1)

Number with fetal genotype data

0

4625 (67.8)

1855 (63.1)

12,183 (83.5)

 

N cases / N controls (Proportion, %)

Stillbirth

4907/107,791 (4.4)

48/4546 (1.0)

31/2588 (1.2)

51/9998 (0.5)

Miscarriage

42,717/107,791 (28.4)

1378/4546 (23.3)

14/2588 (0.5)

2677/9998 (21.1)

Gestational diabetes mellitus

726/170,308 (0.4)

34/6283 (0.5)

136/2657 (4.9)

113/14,375 (0.8)

Hypertensive disorders of pregnancy

2128/174,769 (1.2)

1099/5698 (16.2)

347/2159 (13.8)

1892/12,652 (13.0)

Perinatal depression

5168/20,860 (19.9)

423/5896 (6.2)

312/2245 (12.2)

579/13,865 (4.0)

Preterm birth

551/4811 (10.3) c

285/4931 (5.5)

172/2706 (6.0)

495/12,846 (3.7)

Low offspring birthweight

13,429/149,084 (8.3)

337/6376 (5.0)

167/2725 (5.8)

245/13,690 (1.8)

High offspring birthweight

2716/149,084 (1.8)

113/6376 (1.7)

42/2725 (1.5)

621/13,690 (4.3)

  1. aIn UKB, these variables were measured at the recruitment that is typically many years after pregnancy
  2. bWe report maternal ages at giving their first live birth. UK Biobank women were recruited with an average age of 56.9 (standard deviation 7.8) years
  3. cGestational age was available only in a small subset of UK Biobank women (N=7280)
  4. dThese were maternal ever smoking/drinking in pregnancy
  5. ALSPAC Avon Longitudinal Study of Parents and Children, BiB Born in Bradford, MoBa Norwegian Mother and Child Cohort Study
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BMC Medicine

ISSN: 1741-7015

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