Doctor of Philosophy
Department of Public Health and Nutrition
Stamp, Georgina E., Postnatal depression: prevalence, prediction and preventive intervention randomised trial, Doctor of Philosophy thesis, Department of Public Health and Nutrition, University of Wollongong, 1997. http://ro.uow.edu.au/theses/1705
Depression after childbirth represents a largely under-reported area of maternal morbidity and a major public health issues in Australia (Health Department of Victoria 1990) and world wide (Gitlin & Pasnau 1989). Prior to the following studies, there was no published data on the prevalence of postnatal depression using a South Australian population. This identified gap, and the magnitude of the problem, resulted in the design and conduct of the studies that make up this thesis. The work has resulted in three publications in refereed journals (Stamp & Crowther 1994a, Stamp et al 1995, Stamp et al 1996).
In a preliminary postnatal survey, drawn from a hospital sample of women, in which their views of postnatal care and breastfeeding practices were also sought, postnatal depression was identified as a problem (Stamp & Crowther 1994a). If prediction were possible it could be of value to facilitate the development of strategies for prevention. This consideration led to the modification of an antenatal screening questionnaire developed by Leverton et al (1989) to assess the prediction of postnatal depression. Results of the prediction study of the Modified Antenatal Screening Questionnaire (MASQ), are presented in Chapter 5 of this thesis and in Stamp et al (1996). Those women identified as more vulnerable were randomised and half were offered attendance at three specifically developed supportive and information sharing groups designed to prevent postnatal depression (Chapter 6 and Stamp et al 1995). After the studies and data analysis were complete, participants were sent details of the results and invited to express their feelings about completing the MASQ, and (if applicable), their reasons for not attending the groups. A brief outline of each study and its results follows.
In the first study, women who gave birth to tenn babies over a 6 month period in an Adelaide tertiary hospital completed an Edinburgh Postnatal Depression Scale (EPDS) and a Rosenberg self-esteem scale in hospital and at 6 weeks and an EPDS only at 6 months postpartum (Appendices 1 & 2). A total of 235 women took part in the study of which 222 (95%) returned questionnaires at 6 weeks postpartum and 192 (82%) at 6 months postpartum. Characteristics of the women and their pregnancy outcomes are presented in Chapter 4. The EPDS identified likely major depression (score>12) in 9% of women in hospital and at 6 weeks postpartum (95% CI 5.3%-12.8%). At 6 months this had increased to 10% (95% CI 5.70/0-14.1%). Postnatal depression was significantly correlated with low self-esteem in hospital and at 6 weeks postpartum.
The second study assessed the prediction of postnatal depression. Women at 24 weeks' gestation or less were invited to complete a Modified Antenatal Screening Questionnaire (MASQ) that identified those more vulnerable to becoming depressed after childbirth. Of these 249 women, 144 (58%) screened more vulnerable, and were randomly allocated to attend either a supportive intervention to reduce postnatal depression or to standard care (Chapter 5). At 6 weeks, 12 weeks and 6 months postpartum the participants completed the Edinburgh Postnatal Depression Scale (EPDS).
No difference occurred at 6 weeks postpartum between the MASQ vulnerable group (return rate 64/68) and the MASQ less vulnerable group (return rate 44/51) in the frequency of those who screened as potential candidates for major depression using the EPDS. At 12 weeks a significant difference was found (RR 3.60, 95% CI 1.38-9.36). At 6 months postpartum the relative risk for major depression was undefined.
For major depression the MASQ's sensitivity was 73% at 6 weeks, 91 % at 12 weeks and 100% at 6 months, specificity 43%, 45% and 43% respectively, positive predictive value 17%, 16% and 9% respectively and negative predictive value 91%, 98% and 100% respectively. For minor depression the test's sensitivity was 81 % at 6 weeks, 72% at 12 weeks and 77% at 6 months, specificity 48%, 46% and 43% respectively, positive predictive value 34%, 27% and 16% respectively and negative predictive value 89%,89% and 93% respectively.
In a South Australian population the MASQ was able to predict minor depression with good sensitivity, poor specificity and excellent negative predictive value at 6 weeks postpartum. At 12 weeks and 6 months the test predicted major depression with excellent sensitivity, poor specificity and excellent negative predictive value.
In the third study, a randomised trial design was used to test the hypothesis that women identified as more vulnerable to developing postnatal depression who attend two support and information sharing antenatal groups and one postnatal group have a reduced incidence of postnatal depression from 37% to 15% at 6 weeks, 12 weeks and 6 months postpartum. A modified antenatal screening questionnaire (MASQ), was completed, and those women identified as more vulnerable to postnatal depression were stratified by parity and randomly allocated to receive extra support groups or to a control group. The Edinburgh Postnatal Depression Scale (EPDS) was used to detect postnatal depression.
Attendance at the support groups was lower than anticipate~ 31% overall. Postal EPDS return rates of 92% were achieved at 6 and 12 weeks postpartum and 87% at 6 months postpartum. At six weeks, in the intervention group, 8, (13%) of 64 women scored high (> 12) on the EPDS, compared with 1 I (17%) controls. Similarly, at 12 weeks, 7, (11 %) of 63 versus 10 (15%) of 65 women scored higher than 12. At 6 months the direction of the difference was reversed 9 of 60 (15%) compared with 6 of 61 (10%). None of these small differences was statistically significant, and demonstrate that the intervention did not reduce postnatal depression as hypothesised. More research is needed into ways of reaching and supporting women who may become depressed after the birth of their babies.
In the fourth investigation, results of studies 2 and 3 were mailed to participants and their retrospective views of completing the MASQ in the antenatal clinic sought. In addition, those women randomised to the intervention groups who did not attend were invited to give their reasons. Open-ended questions were used. From a return rate of 111 of 238 (47%), most women (68%), expressed in their own words, a desire to help in research which attempted to find strategies to help unhappy women. Sixteen women responded to a section on group attendance. The two most common reasons given were a feeling of not needing groups (5 of 16, 31%) and transport problems (4 of 16,25%). Most added qualifying statements of support for the research in principle. Out of 111 respondents when asked only 4, (4%) would not participate in such a study again. For others the responses were "yes" (82%) and "maybe" (14%). Participation in the trial and completion of the MASQ were acceptable to a majority of the respondents.