Of the 13
799 eligible mothers, 12
059 (87%) completed at least one of the four questionnaires and 9028 (65%) completed all four. Table shows the mean Edinburgh postnatal depression scale scores for each period. Mean scores were higher in pregnancy than postnatally, with a peak at 32 weeks of pregnancy of 6.72 (SD 4.94) and a lowest value at 8 months postpartum (5.25 (4.61)). The mean change in depression score from that at 18 weeks of pregnancy was −0.097 (95% confidence interval −0.18 to −0.01, P=0.025) at 32 weeks of pregnancy, 0.78 (0.69 to 0.88, P<0.001) at 8 weeks postpartum, and 1.37 (1.27 to 1.46, P<0.001) at 8 months postpartum. Mean change in score was 0.88 (0.79 to 0.97, P<0.001) between 32 weeks of pregnancy and 8 weeks postpartum, 1.46 (1.37 to 1.56, P<0.001) between 32 weeks of pregnancy and 8 months postpartum, and −0.58 (−0.50 to −0.67, P<0.001) between 8 weeks and 8 months postpartum. Women who did not complete all four questionnaires had higher depression symptom scores than women who completed all four. The mean depression scores were therefore higher when partial responders were included (table ).
Edinburgh postnatal depression score during pregnancy and after childbirth
There was a small rise in depression symptom score during pregnancy (mean change 0.10; SE 0.043) and a small drop after childbirth (−0.88; 0.047). These changes were significantly different (difference 0.98, 95% confidence interval 0.83 to 1.13; P<0.001).
Table shows the cumulative frequency of women with increasing Edinburgh postnatal depression scores at the four time points. The distribution did not differ between the time points.
Cumulative number (percentage) of women with various Edinburgh postnatal depression scores at each time point.
Table gives the scores for each item in the questionnaire. A similar pattern was seen at all four time points, but question 3 (I have blamed myself unnecessarily when things went wrong) was rated higher at 18 weeks of pregnancy that at other times and question 6 (things have been getting on top of me) was rated lower at 8 months postpartum than at other times.
Mean score for Edinburgh postnatal depression scale items at each time point among 9028 women with complete data. (Maximum score for each question is 3)
When we repeated the above analyses using the Crown Crisp experiential index depression subscale there was no substantial differences in the findings.
The proportion of women with probable depression (Edinburgh postnatal depression score
13) was 11.8% at 18 weeks of pregnancy, 13.5% at 32 weeks of pregnancy, 9.1 % at 8 weeks postpartum, and 8.1% at 8 months postpartum (table ). In all, 147 (1.6%) women had probable depression at all four time points and 6771 (75%) scored below the threshold at all time points; 436 (4.8%) had probable depression at 32 weeks of pregnancy only and 240 (2.7%) at 8 weeks postpartum only.
Of the 7966 women who were below the threshold for probable depression at 18 weeks of pregnancy, 673 (8.4%) were above the threshold at 32 weeks of pregnancy. Of the 7806 below the threshold for probable depression at 32 weeks of pregnancy, 410 (5.3%) were above the threshold at 8 weeks postpartum. There were 253 (3.2%) fewer women newly rising above the threshold for probable depression after childbirth than during pregnancy (95% confidence interval 2.4% to 4.0%).