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Table 1 Sample characteristics and differences by depressive symptoms

From: Immediate effects of the Fukushima nuclear power plant disaster on depressive symptoms among mothers with infants: a prefectural-wide cross-sectional study from the Fukushima Health Management Survey

  N (%) or Median (Min, Max)  
Characteristics Total a (N = 8196) Depressive symptoms P value b
   Positive (N = 2262) Negative (N = 5934)  
Maternal characteristics     
Mother’s age at the time of pregnancy (years) 30 (15, 51) 30 (16, 45) 30 (15, 51) <0.01
Postpartum days at the time of survey (days) 175 (0, 647) 179 (0, 599) 174 (0, 647) 0.65
Gestational week at the time of disaster (weeks) 19 (0, 41) 20 (0, 41) 19 (0, 41) 0.13
Pregnancy history     
Birth     
0 (First-time mother) 2248 (28.8) 669 (29.8) 1579 (70.2)  
≥1 5562 (71.2) 1463 (26.3) 4099 (73.7) <0.01
Miscarriage     
0 2303 (61.0) 619 (26.9) 1684 (73.1)  
≥1 1475 (39.0) 416 (28.2) 1059 (71.8) 0.37
Still birth     
0 2808 (97.0) 754 (26.9) 2054 (73.2)  
≥1 86 (3.0) 31 (36.1) 55 (64.0) 0.06
Abortion     
0 2462 (70.5) 642 (26.1) 1820 (73.9)  
≥1 1032 (29.5) 365 (35.4) 667 (64.6) <0.01
Psychiatric history     
Before pregnancy     
No 8071 (98.5) 2187 (27.1) 5884 (72.9)  
Yes 125 (1.5) 75 (60.0) 50 (40.0) <0.01
During pregnancy before the disaster     
No 8111 (99.0) 2209 (27.2) 5902 (72.8)  
Yes 85 (1.0) 53 (62.4) 32 (37.7) <0.01
During pregnancy after the disaster     
No 7877 (96.1) 2075 (26.3) 5802 (73.7)  
Yes 319 (3.9) 187 (58.6) 132 (41.4) <0.01
Obstetrical characteristics     
Mode of pregnancy     
Natural 7841 (95.9) 2178 (27.8) 5663 (72.2)  
Induced ovulation, or artificial insemination, in vitro fertilization 333 (4.1) 80 (24.0) 253 (76.0) 0.13
Mode of delivery     
Vaginal birth 5570 (69.1) 1507 (27.1) 4063 (72.9)  
Cesarean section, vacuum, or forceps 2486 (30.9) 714 (28.2) 1772 (72.3) 0.12
Gestational week at birth     
≥37 7859 (96.1) 2166 (27.6) 5693 (72.4)  
<37 (Preterm) 317 (3.9) 90 (28.4) 227 (71.6) 0.75
Obstetrical complicationsc before the disaster     
No 6920 (85.8) 1809 (26.1) 5111 (73.9)  
Yes 1154 (14.2) 390 (34.1) 755 (65.9) <0.01
Obstetrical complicationsc after the disaster     
No 6673 (85.7) 1692 (25.4) 4981 (74.6)  
Yes 1116 (14.3) 360 (32.3) 756 (67.7) <0.01
Infant characteristics     
Sex     
Girl 3937 (48.4) 1100 (27.9) 2837 (72.1)  
Boy 4194 (51.6) 1143 (27.3) 3051 (72.8) 0.49
Birth weight     
2500 g or higher 7536 (92.6) 2080 (27.6) 5456 (72.4)  
1500–2499 g 564 (6.9) 148 (26.2) 416 (73.8) 0.49
Less than 1500 g 36 (0.4) 15 (41.7) 21 (58.3) 0.06
Asphyxia     
No 7812 (98.9) 2152 (27.6) 5660 (72.5)  
Yes 90 (1.1) 35 (38.9) 55 (61.1) 0.02
Congenital anomaly     
No 7693 (97.4) 2098 (27.3) 5595 (72.7)  
Yes 205 (2.6) 86 (42.0) 119 (58.1) <0.01
  1. aColumn proportions are shown for the total distribution.
  2. bWilcoxon–Mann–Whitney rank sum test was used for continuous variables and chi-squared tests were used for categorical variables.
  3. cExcluding mental health disorders that are listed above in maternal psychiatric history.