Table 1 Basic characteristics of the study participants
Characteristic | n (%) |
|---|---|
Age | |
 ≤ 25 | 17 (11.4) |
 26–30 | 71 (47.7) |
 31–35 | 44 (29.5) |
 > 35 | 17 (11.4) |
 Missing | 0 |
Parity | |
 0 | 91 (61.1) |
 1 | 43 (28.9) |
 ≥ 2 | 15 (10) |
 Missing | 0 |
Pre-existing chronic diseases | |
 No | 135 (90.6) |
 Yes | 12 (8.1) |
 Missing | 2 (1.3) |
Pre-pregnancy Body Mass Index (kg/m2) | |
 Underweight (< 18.5) | 8 (5.4) |
 Normal (18.5–24.9) | 84 (56.4) |
 Overweight (25–29.9) | 20 (13.4) |
 Obese (≥30) | 12 (8.1) |
 Missing | 25 (16.7) |
Smoking before pregnancy | |
 Never | 94 (63.1) |
 Former smoker | 21 (14.1) |
 Missing | 34 (22.8) |
Alcohol consumption before pregnancy | |
 No | 16 (10.7) |
 Yes | 99 (66.4) |
 Missing | 34 (22.8) |
Ethnic background | |
 European | 112 (75.2) |
 Non-European | 4 (2.7) |
 Missing | 33 (21.1) |
Educational attainment | |
 Low (Basic level) | 15 (10.1) |
 Intermediate (Secondary school) | 15 (10.1) |
 High (Higher education) | 85 (57.0) |
 Missing | 34 (22.8) |
Pre-pregnancy employment | |
 No | 7 (4.7) |
 Yes | 107 (71.8) |
 Missing | 35 (23.5) |
Daily hair washing | |
 No | 97 (65.1) |
 Yes | 18 (12.1) |
 Missing | 34 (22.8) |
Season of 2nd trimester sampling (n=133) | |
 Autumn | 28 (21.2) |
 Winter | 23 (17.3) |
 Spring | 38 (28.6) |
 Summer | 44 (33.1) |
 Missing | 0 |
Season of 3rd trimester sampling (n=81) | |
 Autumn | 23 (28.4) |
 Winter | 21 (25.9) |
 Spring | 12 (14.8) |
 Summer | 25 (30.9) |
 Missing | 0 |