Background: The majority of randomised controlled trials examining the effectiveness of antenatal group interventions at preventing postnatal depression in "at risk" women have used a "psychoeducational" intervention. The aim of the present study is to evaluate the effectiveness of an antenatal cognitive behavioural group intervention in a primary care setting for pregnant women identified with mild to moderate symptoms in pregnancy and/or at risk of developing depression or anxiety in the perinatal period.
Method: Subjects were randomised to a CBT group intervention or control condition (information booklet) and administered the EPDS and STAI at pre (Time 1) and post intervention (Time 2), and at 2 months (Time 3) and 4 months postpartum (Time 4). MINIs were administered at Times 1, 3 and 4.
Results: Of the 774 women approached, 277 accepted and were suitable; thus 191 were randomised to the CBT intervention and 86 to the control condition. The subsequent 52% drop-out left 89 women "completing" the CBT groups and 43 in the control group; these two groups were well matched on demographic variables. Intention to treat analyses revealed relatively low mean baseline EPDS scores (means 6.88 -8.16) with no reduction in EPDS scores in either group from Time 1 to Time 4. MINI depression criteria were fulfilled by 19% of all participants at Time 1 but there was no reduction in depression in either group; in contrast those with MINI anxiety diagnoses reduced from 28% in late pregnancy to 16% at four months postpartum in the CBT group with similar reductions in the control group. Analyses on the 132 "completers" showed significant symptomatic improvement over time for both the CBT group and control condition. Depression scores in the most symptomatic women (EPDS>12; N=19) decreased steadily by over 50% over the total time course but there were no differences in improvement between the CBT and control groups.
Limitations: A number of methodological factors may have obscured our results including a tendency to natural remission in mildly symptomatic subjects and the possibility that our control condition was therapeutic in itself.
Conclusion: While a modest reduction in depression scores was noted in study "completers", both the CBT group intervention control condition were equally beneficial. The reasons for this finding include the low symptom level at baseline; the potential effectiveness of the control condition; and the brevity of the intervention.