Table 1.
Baseline characteristics of sample
| Characteristic | All sample | Depressive episode | No depressive episode | Test statistica p-value |
|---|---|---|---|---|
| Participants, n (% total) | 3208 (100) | 227 (7) | 2981 (93) | – |
| Male sex, n (column %) | 1553 (48) | 62 (27) | 1491 (50) | 9.167; p = 0.002 |
| Smoking at 18 years, n (column %) (current) | 231 (10) | 27 (11) | 220 (7) | 7.535; p = 0.006 |
| Maternal EPDS scoreb, mean (s.d.) | 5.89 (4.65) | 5.78 (4.65) | 5.98 (4.69) | 0.476 p = 0.322 |
| Maternal education (A-levels or above), n (column %) | 1116 (35) | 74 (33) | 1049 (35) | 0.267 p = 0.096 |
| Alcohol usec (greater than once per week), n (column %) | 1320 (41) | 132 (58) | 1070 (36) | 8.756 p = 0.024 |
| Physical activityd (greater than once per week), n (column %) | 2213 (69) | 78 (35) | 2337 (78) | 9.967 p < 0.001 |
| Father's social class, n (column %) | 4.235; p = 0.055 | |||
| I | 186 (6) | 15 (7) | 184 (6) | |
| II | 1119 (35) | 73 (32) | 1077 (36) | |
| III – non-manual | 1257 (39) | 87 (38) | 1145 (38) | |
| III – manual | 96 (3) | 7 (3) | 85 (3) | |
| IV | 465 (14) | 36 (16) | 394 (13) | |
| V | 95 (3) | 9 (4) | 96 (3) | |
| White British ethnicity, n (column %) | 3143 (98) | 221 (97) | 3175 (99) | 0.243; p = 0.588 |
| BMI at 18 years, mean (s.d.), kg/m2 | 22.68 (3.81) | 23.06 (5.38) | 22.65 (3.79) | 8.141; p = 0.330 |
| BMI at 9 years, mean (s.d.), kg/m2 | 17.54 (2.53) | 17.88 (2.23) | 17.51 (2.46) | 1.967; p = 0.223 |
| FPG at 18 years, mean (s.d.), mmol/L | 5.04 (0.59) | 4.95 (0.76) | 5.09 (0.48) | 0.044; p = 0.389 |
| HOMA2 at 18 years, mean (s.d.) | 0.92 (0.73) | 1.32 (0.55) | 0.87 (0.44) | 3.860; p = 0.035 |
| CRP at 18 years, mean (s.d.), mg/L | 1.11 (1.41) | 1.20 (1.05) | 1.08 (1.43) | 0.423; p = 0.701 |
| IL-6 at 9 years, mean (s.d.), pg/mL | 1.21 (0.78) | 1.27 (1.58) | 1.18 (1.52) | 7.687; p = 0.004 |
| CRP at 9 years, mean (s.d.), pg/mL | 0.68 (2.52) | 0.76 (1.92) | 0.65 (3.54) | 4.723; p = 0.226 |
a
Categorical variables (sex, social class, ethnicity, smoking) were compared using the χ2 test, normally distributed continuous variables (FPG, birthweight, gestational age) were compared using the two tailed t test; non-normally distributed continuous variables (HOMA2, CRP, IL-6, BMI) were compared using the Mann–Whitney U test.
b
Maternal EPDS score recorded at 8 week post-partum.
c
Frequency participant has had drinks containing alcohol.
d
Physical activity corresponded to frequency respondent engaged in going to gym, brisk walking or any sports activity during the past year