Table 1 Characteristics of the study participants by depression status at 6 weeks postpartum (EPDSa score 0–11 vs. 12–30) (n = 4313).

From: Predicting women with depressive symptoms postpartum with machine learning methods

Characteristics Missing values EPDSa at 6 weeks postpartum po
0–11 (n = 3736) 12–30 (n = 577)
N (%) or median (IQRb)
Age (years) 3 31 (6) 31 (6) 0.247
BMI (kg/m2) before pregnancy 162 22.8 (4.4) 23.3 (5.5) 0.001
Height at gestational week 17 (cm) 151 168 (9) 167 (8) 0.305
University level education (vs. less) 268 2734 (78%) 387 (72%) 0.001
Employment 264    < 0.001
 Full-time work   2291 (65%) 310 (57%)  
 Part-time work   696 (20%) 102 (19%)  
 Studying   242 (7%) 49 (9%)  
 Maternity leave   110 (3%) 15 (3%)  
 Sick-leave   89 (3%) 26 (5%)  
 Unemployed   78 (2%) 41 (7%)  
Marital status (single vs. married/cohabiting) 9 55 (1.5%) 16 (2.8%) 0.022
Country of origin (scandinavia vs. other) 184 3311 (93%) 499 (91%) 0.193
Depression historyc 185 959 (27%) 296 (54%) < 0.001
Contact with psychiatrist (self-reported)d 250 285 (8%) 98 (18%) < 0.001
Contact with psychologist (self-reported)d 250 1190 (34%) 299 (55%) < 0.001
Hypomanic episodes (1 or more vs. none)d 270 141 (4.0%) 50 (9.3%) < 0.001
Premenstrual syndrome history (based on the ICD and ACOG criteria)d 303 169 (4.9%) 79 (15%) < 0.001
History of pregnancy loss 2072 21 (1.1%) 5 (1.6%) 0.477
Parity 303    0.072
 0   1934 (55%) 309 (60%)  
 1   1082 (31%) 154 (30%)  
 2 or more   477 (14%) 54 (10%)  
Smoking, ever 175 1157 (32%) 197 (36%) 0.096
Snuff, before pregnancy 402 251 (7.4%) 40 (7.6%) 0.846
Sleep before pregnancy (hours per day) 179    0.005
 < 6   124 (3%) 32 (6%)  
 6–8   29 27 (82%) 421 (77%)  
 > 8   534 (15%) 96 (17%)  
Migrained 295 584 (17%) 120 (22%) 0.002
Irritable bowel syndromed 295 127 (3.7%) 32 (5.9%) 0.011
Alcohol problemsd 295 5 (0.1%) 5 (0.9%) 0.001
Allergiesd 295 764 (22%) 119 (22%) 0.951
Endocrine problemsd 295 124 (3.6%) 25 (4.6%) 0.220
Hypertensiond 295 55 (1.6%) 14 (2.6%) 0.091
Pain problemsd 295 137 (3.9%) 43 (8.0%) < 0.001
Intimate partner violenced 275 362 (10%) 107 (20%) < 0.001
Pregnancy-related variables
Planned pregnancy 288 481 (14%) 121 (22%) < 0.001
Assisted reproductive technology treatment 424 369 (11%) 46 (8.7%) 0.120
Several ultrasounds during gestation 298 2241 (65%) 371 (69%) 0.048
Fear of childbirth 254    < 0.001
 No fear   2774 (79%) 336 (62%)  
 Fear of caesarean section   339 (9.6%) 73 (14%)  
 Fear of vaginal delivery   208 (5.8%) 61 (11%)  
 Severe fear   200 (5.6%) 68 (13%)  
Visit at fear of childbirth support unit 250 77 (2.2%) 19 (3.5%) 0.061
Negative delivery expectations 305 504 (15%) 131 (25%) < 0.001
Pregnancy nausea 281    < 0.001
 No   705 (20%) 74 (14%)  
 Yes, without medication   2313 (66%) 363 (67%)  
 Yes, with medication   476 (14%) 101 (19%)  
SSRIf use during pregnancy 368 132 (3.9%) 39 (7.5%) 0.001
Anxiety during pregnancyg 237 1032 (29%) 387 (72%) < 0.001
Depression during pregnancyh 162 472 (13%) 298 (53%) < 0.001
Sleep during pregnancy (hours per day)i 266    < 0.001
 < 6   322 (9%) 98 (18%)  
 6–8   2340 (67%) 332 (61%)  
 > 8   843 (24%) 112 (21%)  
Self-reported pregnancy complications (any)j 354 1471 (42.7%) 215 (42.0%) 0.771
Gestational diabetesj 136 35 (1.0%) 19 (3.5%) < 0.001
Preeclampsiaj 136 117 (3.2%) 23 (4.2%) 0.242
Anaemiaj 354 103 (3.0%) 21 (4.1%) 0.177
Hypertensionj 347 165 (4.8%) 41 (8.0%) 0.002
Symphysiolysisj 683 1212 (39%) 228 (47%) < 0.001
Pregnancy length (days) 194 280 (13) 280 (14) 0.103
Childbirth-related variables
Delivery month 1 6 (6) 6 (6) 0.386
Induction 301 651 (18.6%) 100 (19.3%) 0.697
Mode of delivery 0    0.107
 Spontaneous vaginal   2795 (75%) 402 (70%)  
 Elective caesarean section   271 (7%) 47 (8%)  
 Acute caesarean section   320 (9%) 64 (11%)  
 Emergency caesarean section   33 (1%) 7 (1%)  
 Instrumental delivery   317 (8%) 57 (10%)  
Postpartum hemorrhage (≥ 1000 ml vs. < 1000 ml) 301 221 (6.3%) 46 (8.9%) 0.028
Epidural anaesthesia 286 1306 (37%) 238 (46%) < 0.001
Laceration (Grade III/IV vs. I/II) 146 103 (2.8%) 14 (2.6%) 0.712
Infant-related variables
Gender (female) 171 1733 (48%) 269 (50%) 0.458
Birthweight (kg) 204 3.6 (0.65) 3.6 (0.70) 0.201
Birth length (cm) 219 51 (2.5) 51 (3.0) 0.242
Head circumference (cm) 1184 35 (2.0) 35 (2.0) 0.672
Apgar score (1st min) 222    0.027
 0–3   26 (1%) 6 (1%)  
 4–6   111 (3%) 28 (5%)  
 7–10   3418 (96%) 502 (94%)  
Umbilical artery base deficit 991 − 2.9 (4.2) − 2.6 (4.6) 0.250
Umbilical artery pH 949 7.3 (0.10) 7.3 (0.11) 0.519
Newborn admission to neonatal unit 286 300 (8.6%) 69 (13%) < 0.001
Postpartum variables
Negative delivery experience 411 217 (6.4%) 85 (17%) < 0.001
Partner helpful with infant 40    < 0.001
 Yes, a lot   2334 (63%) 300 (53%)  
 Yes, a little   1281 (35%) 235 (41%)  
 No   87 (2%) 36 (6%)  
Breastfeeding 11    < 0.001
 Yes, exclusive   2918 (78%) 354 (62%)  
 Yes, non-exclusive   576 (16%) 146 (25%)  
 No   233 (6%) 75 (13%)  
Stressful life events past 6 months (3–30 vs. 0–2) 13 395 (11%) 129 (22%) < 0.001
Psychometric scales
ASQ [pregnancy week 32]k
 Distance 2658 2.8 (1.1) 3.4 (1.4) < 0.001
 Insecure and repudiation connection 2658 2.1 (0.86) 2.3 (1.0) < 0.001
 Trust 2658 4.8 (1.0) 4.3 (1.3) < 0.001
 Consents 2658 2.9 (1.3) 3.7 (1.4) < 0.001
 Relation 2658 3.0 (1.0) 3.5 (1.1) < 0.001
SOC (total score) [pregnancy week 32]l 2095 154 (28) 131 (31) < 0.001
LITE (number of events) [12 months postpartum]m 1696 3.0 (3.0) 4.0 (4.0) < 0.001
Resilience Scale-14 [pregnancy week 32] 1982 81 (15) 72 (24) < 0.001
Beck anxiety inventory (moderate/severe vs. minimal/mild) [pregnancy week 32] 2015 299 (15%) 162 (50%) < 0.001
SSP-Neuroticism score [pregnancy week 32]n 3230 328 (66) 387 (64) < 0.001
SSP-Aggressiveness score [pregnancy week 32] 3236 195 (26) 203 (26) 0.001
SSP-Sensation Seeking score [pregnancy week 32] 3224 94 (19) 95 (17) 0.258
  1. Bold values indicate p < 0.05.
  2. aEdinburgh Postnatal Depression Scale.
  3. bInterquartile range.
  4. cSelf-reported and/or diagnosed by psychiatrist.
  5. dPregnancy week 17, self-reported.
  6. eEPDS ≥ 12 at pregnancy week 17 or 32 or at delivery.
  7. fSelective serotonin reuptake inhibitors.
  8. gBased on either the Beck Anxiety Inventory, the State Trait Anxiety Inventory (STAI) or the anxiety subscale of the EPDS (EPDS 3A, items 3–5).
  9. hEPDS ≥ 12 at pregnancy week 17, 32 or 38.
  10. iPregnancy week 32.
  11. jSelf-reported, pregnancy week 32.
  12. kAttachment Style Questionnaire.
  13. lSense of Coherence Questionnaire-29.
  14. mLifetime Instances of Traumatic Events.
  15. nSwedish Universities scales of Personality.
  16. oBased on the Mann–Whitney test for continuous variables and the Pearson Chi-square test for the categorical variables.