- Email: [email protected]
Risk factors for postnatal depression
Aust. Mid:J.ACM 2004 17: 2:10-15
Risk factors for postnatal depression Lizette A Willinck and Susan M Cotton
ABSTRACT A prospective longitudinal study of 620 women investigated the association between a range of risk factors and postnatal depression (PND). Univariate analyses of results demonstrated seven antenatal and three perinatal variables significantly associated with PND. Antenatal risk factors included relationship problems, antenatal depression and limited supports. These factors had previously been reported in the literature. Additionally this study highlighted the significance of domestic violence as a risk factor. Perinatal factors significantly associated with PND were severe blues/highs, no partner or support person at birth and dissatisfaction with care in labour. Logistic regression analysis of the 10 combined antenatal and perinatal risk factors demonstrated that only three factors were found to be significant predictors of depression in the final model. These were antenatal depression, severe blues/highs and dissatisfaction with care in labour. With these variables in the regression equation, none of the other risk factors were contributing significantly to the prediction of PND.
Introduction Lowered mood, labile mood, tearfulness, irritability, anxiety, panic attacks and suicidal i d e a s . . , these are just some of the well-recognised symptoms of postnatal depression (Buist 1995). Although approximately 14% of childbearing Australian women experience postnatal depression (Brown et al. 2001), progress towards reducing this condition has been slow. One of the reasons is a difficulty in identifying Correspondence to LizetteA Willinck B App Sc (Speech Pathology) Research Project Coordinator PO Box 326 Albury NSW 2640 email [email protected] Susan M Cotton BBSc (hons), Grad Dip App Sc (statistics), M App Sc (statistics) Biostatistician Dept. Psychiatry University of Melbourne
10
AustralianMidwifery:Journal of the Australian College of Midwives June 2004
women who may be at risk. Risk factors for PND are many and varied. Factors linked to PND may present at varying stages of the pregnancy to parenthood continuum. This continuum of risk factors can arguably be grouped into four categories; antenatal risk factors, birth risk factors, immediate postpartum risk factors and postnatal risk factors. Despite the vast literature on risk factors for PND, most studies have focused simply on factors within specific risk categories, such as considering only antenatal risk factors. This has limited the scope of findings. Three major studies focused exclusively on antenatal risk factors for PND. Wilson et al (1996) conducted a comprehensive review of antenatal risk factors for PND and identified three antenatal psychosocial risk factors that had good evidence of an association with PND. These factors were relationship problems, recent stressful life events and antenatal depression. A further three factors found to have fair evidence of an association with PND were lack of social support, domestic violence and current/past psychiatric history. In the same year Cooper et al (1996) recruited a sample of over 6000 pregnant British women and administered a questionnaire to detect the presence of factors likely to increase risk of PND. Unfortunately the antenatal risk factors found to contribute most significantly to the development of PND were not specified. A study of 574 Australian women conducted by Webster et al. (2000) found three antenatal risk factors significantly linked to PND. These were low social support, psychiatric history and history of PND. Unfortunately the study omitted antenatal depression and recent stressful life events; two potential risk factors found by Wilson et al. (1996) to be of greatest significance. Only one major study has investigated associations between PND and birth and immediate postpartum risk factors. This study by Astbury et al. (1994) of 790 Victorian women found six factors associated with increased odds of depression in the final logistic model. These risk factors were; having a first child over the age of 34, assisted delivery, bottle feeding, dissatisfaction with antenatal care, unwanted people at the birth and lacking confidence to look after the baby at the time of leaving hospital. Although a small number of antenatally-evidenced 'social factors' were included in the study, most antenatal psychosocial risk factors mentioned in previously cited investigations were omitted. Two studies have attempted to investigate a range of antenatal, birth and immediate postpartum risk factors. Nielsen et al. (2000) tested the predictive power of a range of demographic, obstetric and psychosocial PND risk factors in a sample of 5252 women. Risk factors identified by multivariate logistic regression analysis as being significantly associated with PND were psychological distress in late pregnancy, social isolation, high parity and previous psychiatric history. However, several risk factors identified as significant in previous studies were not investigated. These
Lizette Willinck and Susan Cotton included relationship problems, domestic violence and dissatisfaction with care in labour. A recent Australian study by Webster (2003) screened 1762 women for 11 antenatal risk factors and 10 birth/immediate postpartum risk factors. Individual antenatal risk factors shown to be statistically associated with PND were past psychiatric history, family history of mood disorder, having a mother who had PND, low family support and conflict with partner. Individual postnatal risk factors shown to be statistically associated with PND were low satisfaction with delivery, low postnatal support and reduced parent-child interaction. Multivariate analysis was not conducted and unfortunately antenatal depression was not included as an antenatal risk factor. One study has attempted to investigate PND risk factors from the entire pregnancy to postnatal continuum, but this otherwise rigorous meta-analysis by Beck (2001) investigated only a relatively small number of risk factors (a total of 10 antenatal, two immediate postpartum, one postnatal and no birth risk factors). Selection criteria for the risk factors chosen was not specified. In conclusion, there has been a tendency for previous studies to either ignore the continuum of antenatal to postnatal risk factors for PND or to omit significant individual risk factors. The aim of this study was therefore twofold. The first aim was to include the spectrum of antenatal to birth and immediate postpartum risk categories. The second aim was to include all individual risk factors that had been deemed significant by a majority of previous studies and could be readily assessed for in a clinical setting. This led to a total of 15 antenatal risk factors, seven birth and six immediate postpartum risk factors for PND. Investigation of postnatal risk factors such as infant temperament could not be included in this study due to time frame and budgetary restrictions. This study formed part of a larger initiative, the three-year Hume Region Antenatal Risk Assessment Project, which aimed to better identify and assist not only women at risk of postnatal depression, but all psychosocially vulnerable pregnant women.
Methods In August 2000 a prospective longitudinal study of a single cohort of women recruited from five Maternity Hospitals in the Hume Region of north east Victoria commenced. The hospitals involved were Wodonga Regional Health Service, Goulburn Valley Hospital, Wangaratta District Base
Hospital, Seymour and District Memorial Hospital and Alpine Health. Funding was provided by the Hume Region Department of Human Services Maternity Services Enhancement Strategy and approval to conduct the study was obtained from the Victorian Department of Human Services Ethics Committee. Women consenting to participate in the study were screened with the following instruments:
Maternity Psychosocial Risk Assessment Tool (M PRAT) This tool was developed for the Hume Region Antenatal Risk Assessment Project and administered by midwives trained in its use. It consisted of an antenatal and a postnatal component. The antenatal component took approximately 45 minutes to administer. It contained probes to determine the presence/absence of 15 risk factors for PND that had been determined following extensive literature review. Risk factors included domestic violence, which was screened for with four questions pertaining to physical or emotional abuse over the past year. These questions had been developed by the Initiative to Combat the Health Impact of Domestic Violence Against Women (Queensland Health 2000). The postnatal component of the MPRAT was completed two to three days postnatally and took approximately 15 minutes to administer. It contained probes to determine the presence/absence of seven birth and six immediate postpartum risk factors for PND (referred to collectively as perinatal risk factors).
Edinburgh Postnatal Depression Scale (Cox et al. 1987) The Edinburgh Postnatal Depression Scale (EPDS) is one of the most widely used PND screening scales in Australia. It has been validated for use in Australia (Boyce et al. 1993) and is the only self-report scale that has been validated for use antenatally and postnatally. As with all screening tools, the scale cannot in itself confirm a diagnosis of PND, however a score of 10-12 is widely used to indicate possibility of minor depression and a score of greater than 12 indicates significant or major depression is likely. Participants were investigated on the following three occasions: 1. During second or third trimester of pregnancy. Administration of the antenatal component of the
Table I Demographic variables for postnatal depression Demographic variable
Parity Age
M (SD) M (SD)
Marital status
Married De facto Single
No P N D (EPD$ ~ 12)
PND (EPDS > 12)
0.86 (I. 12) 29.3 (5.5)
0.92 (I. 19) 29.2 (7.2)
%(n)
p value
1,79*
0.94* 0.001 #
75. I (250) 15.9 (53) 9.0 (30)
40 (I 0) 40 (10) 20 (5)
*p values from independent groups t-tests; #p values from chi square test Australian Midwifery: Journal of the Australian College of Midwives June 2004
II
Australian Midwifery: Journal of The Australian College of Midwives T a b l e 2 Antenatal risk factors for postnatal depression
Antenatal risk factor No P N D Domestic violence
Relationship problems
Antenatal depression
Late/limited antenatal care
Limited supports
Financial difficulties
History of postnatal depression
Recent significant stressful life events
Poor relationships with parents
(EPDS ~ 12) P N D
History of childhood abuse
Single parent
Other psychological/ psychiatric history Unwanted pregnancy
Born overseas NESB
Odds ratio
p value*
20.56
< 0.00 I
9.98
< 0.00 I
8.58
< 0.00 I
6.89
0.07
4.95
< 0.00 I
4.64
0.003
4.13
0.006
3.18
0.005
2.89
0.09
2.89
0.098
2.70
O. 12
2.69
0.08 I
2.37
0.06
N/A
0.784
N/A
0.78
1.2%
20%
(n = 4)
(n = 5
4.5%
32.0%
( n = 15)
(n=8)
12.9%
56.0%
(n = 43)
(n = 14)
0.6%
4.0%
(n = 2)
(n = I)
10.2%
36.0%
(n = 34)
(n = 9)
45. 1%
20.0%
( n = 17)
(n=5)
5.7%
20.0%
(n-- 19)
(n=5)
19.8%
44.0%
(n = 66)
(n = II)
4.5% ( n = 15)
Age less than 20 years
(EPDS > 12)
12.0% (n=3)
4.5%
12.0%
(n = 15)
(n = 3)
4.8%
12.0%
(n= 16)
(n--3)
6.6%
16.0%
(n = 22)
(n = 4)
14. 1%
28.0%
(n = 47)
(n = 7)
0.3%
0.0%
(n = I)
(n = 0)
0.3%
0.0%
(n = I)
(n = 0)
*p values obtained from chi square analyses with df = I N/A statistics such as chi square and the odds ratio not calculated due to null cells
12
AustralianMidwifery: Journal of the Australian College of MidwivesJune 2004
Lizette Willinck and Susan Cotton
MPRAT, including EPDS.Two to three days post natally. 2. Administration of the postnatal component of the MPRAT. 3. Six to eight weeks postnatally. Administration of the EPDS by Early/Maternal and Child Health Nurses (E/MCHNs). Data were analysed using the Statistical Package for Social Sciences (SPSS version 11.0.05). Chi square tests were used to assess associations between PND and categorical risk factors. For these univariate analyses alpha was set at 0.01 to reduce the chances of type I error. Odds ratios were used to provide a measure of association between two values and an index of relative risk. Logistic regression was used to determine which variables predicted PND.
Results A total of 734 pregnant women attending antenatal bookings at the five Hume Region hospitals were asked to participate in the study. Of the women, 620 agreed to participate, representing a consent rate of 84%. Of the women who participated, only 58% (358/620) were screened for PND at their six to eight week E/MCHN postnatal visit. Reasons for poor compliance with the postnatal EPDS screening were inability to screen due to conflict with another study (14%), women not locatable (13%), failure to attend appointment (8%), not screened by E/MCHN (6%) and refusal to be screened (1%). Women that were assessed postnatally with the EPDS were divided into two groups according to EPDS scores: no PND (EPDS score 12 or less) and PND (EPDS score greater than 12). Seven per cent of screened women (25/358) scored greater than 12, indicating probable major PND. Although it is recognised that an EPDS score of greater than 12 is merely indicative of depressive symptoms, for the purposes of this report women scoring in this category will henceforth be referred to as having PND.
Demographic variables associated with P N D Several demographic variables were examined with regards to PND (Table 1). Women in the PND versus no PND groups were similar in terms of parity and mean age but differed in terms of marital status. Single and defacto women were significantly more likely to develop PND than married women, X22 = 14.48, p = 0.001.
Antenatal risk factors associated with P N D Table 2 comprises the percentages of women with and without PND with each of the 15 antenatal risk factors. Seven antenatal variables were significantly associated with PND. Domestic violence, relationship problems and antenatal depression yielded the highest odds ratios, indicating that these were the most important risk factors for developing PND. For example, women who had experienced domestic violence in the past year were 20 times at greater risk for developing PND than women who had not experienced domestic violence.
Perinatal risk factors associated with P N D Birth and immediate postpartum risk factors were collectively termed perinatal risk factors. Table 3 comprises the percentages of women with and without PND with each of the perinatal risk factors. Three factors were significantly associated with PND. These were severe blues or highs, no partner or support person at birth and dissatisfaction with labour. Women who had experienced severe blues or highs were almost 29 times more likely to have PND than women who did not experience severe mood swings.
Multivariate analysis of risk factors associated with P N D A standard logistic regression was conducted to determine which antenatal and perinatal risk factors best predicted PND and to determine the model of best fit. See Table 4. All significant risk factors from the chi-square analyses were entered into the logistic regression equation. A test of the full model with 10 predictors against a constant only model was statistically significant, chi square X210 = 58.67, p < 0.001, with a considerable amount of the variance in PND being explained by the predictors, Nagelkerke R 2 -- .38. Only three were found to be significant predictors of depression in the final model. These were antenatal depression, severe blues or highs and dissatisfaction with care in labour. With these variables in the regression equation, none of the other risk factors were contributing significantly to the prediction of PND.
Discussion This study aimed to determine the relationship between a range of antenatal and perinatal risk factors and PND. Results indicated some important risk factors requiring further investigation and also yielded interesting data on incidence of PND in a regional/rural area. Only 7% of the women in the final sample screened positive for major PND. This figure was comparable to an earlier unpublished local study of Albury women (Willinck 2000) in which 6% of women screened (n = 406) were found to have major PND. It was also comparable to a large Danish study (Nielsen et al 2000) in which 5.5% of women examined (n = 5252) developed PND. However it was considerably lower than many other studies including the latest Victorian Survey of Recent Mothers in which incidence of PND was 14% (Brown et al. 2001). There are several possible explanations for the lower than expected incidence of PND in this study. One methodological factor for consideration is that the Survey of Recent Mothers was based on EPDS screening conducted eight to nine months postnatally, compared with the six to eight week postnatal time frame in this study. Another factor for consideration is the 42% attrition rate. Posthoc analyses indicated that a disproportionate number of the women lost to the study had antenatal risk factors for depression. Had they been included in the final sample the overall incidence of PND may have been higher. A final explanation is that incidence of PND may be lower in rural/regional areas. Australian Midwifery: Journal of the Australian College of Midwives June 2004
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Australian Midwifery: Journal of The Australian College of Midwives
T a b l e 3 Perinatal risk factors f o r postnatal depression
(EPDS < 12) P N D
(EPS > 12)
Odds ratio
p value*
0.3%
8.0%
28.87
< 0.001
(n = I)
(n = 2)
0.3%
4.0%
13.83
0.017
(n = I)
(n = I)
0.9%
8.0%
9.56
0.004
(n = 3)
(n = 2)
2.7%
16.0%
6.86
0.001
(n = 9)
(n -- 4)
Lack of parent skills or lack of
2.7%
8%
3.13
0.140
confidence to look after baby
(n = 9)
(n = 2)
5.4%
8.0%
1.52
0.590
(n = 18)
(n = 2)
15.6%
20.0%
1.35
0.560
(n = 52)
(n = 5)
4.8%
4.0%
0.83
0.850
( n = 16)
( n = I)
21.6%
16.0%
0.69
0.510
(n = 72)
(n = 4)
0.3%
0.0
N/A
0.780
(n = I)
(n = O)
0.3%
0.0%
N/A
0.780
(n = I)
(n = 0)
2.1%
0.0%
N/A
0.460
(n = 7)
(n = 0)
1.2%
0.0%
N/A
0.532
(n = 4)
(n = 0)
Perinatal risk f a c t o r N o P N D
Severe blues or high
Unwanted people at births
No partner or support person at birth
Dissatisfied with care in labour a n d / o r no say in decisions
Late birth complications or health problems
Problems with baby or significant feeding problems
Premature or post mature births
Birth not to plan including assisted birth or significant complications
Multiple births
Negative neutral feelings about baby or detatchment from baby
Early discharge from hospital not by patient choice
No partner or other support person after discharge
*p values obtained from chi square analyses with df = I N/A statistics such as chi square and the odds ratio not calculated due to null cells
14
AustralianMidwifery:Journalof the AustralianCollegeof MidwivesJune2004
Lizette Willinck and Susan Cotton
This suggestion is supported by a finding from the 1989 Victorian Survey of Recent Mothers, which indicated that lower odds of depression were significantly associated with non-metropolitan residence (Astbury et al 1994). Interestingly this finding was not replicated in the 2000 Survey of Recent Mothers (Brown et al. 2001). Chi square tests of the associations between antenatal risk factors and PND supported previous findings regarding the strong links between PND and relationship problems, antenatal depression, limited supports, history of PND and significant stressful life events (Wilson et al. 1996, Beck 2001). However it also found that the antenatal risk factor with the highest odds ratio was domestic violence. Although this finding needs to be treated with caution due to the small sample size it is of interest given it was a factor excluded by many authors (Astbury et al. 1994, Cooper et al. 1996, Nielsen et al. 2000, Beck 2001). Webster et al. (2000, 2003) arguably included potential indicators of domestic violence in their 'conflict with partner' and 'controlled by partner' risk factors, but they did not report these factors as being significantly associated with PND. Published studies on the relationships between perinatal risk factors and PND are limited. Therefore the chi square analyses conducted in this study are a useful contribution to the literature. The results from this study support previous findings that severe blues or highs (Beck 2001, Webster et al. 2003), no partner or support person at birth (Astbury et al. 1994) and dissatisfaction with care in labour (Webster 2003) are all significantly associated with PND. Multivariate analysis conducted with this data suggest that in the final model only three risk factors were significant predictors of PND. However, these results should be treated with particular caution due to the sample size. Investigation of the associations between PND and protective or resilience factors was outside the scope of this study. However, further studies into the role of high self esteem, good social supports and other protective factors would be welcome contributions to the literature. In conclusion, this study indicates that future research into risk factors for PND should include a range of antenatal, birth, immediate postpartum and, where possible, postnatal
risk factors for PND, with consideration also being given to the role of protective factors. The importance of including antenatal depression , domestic violence, dissatisfaction with care in labour and severe blues/highs as risk factors is emphasised. It is also suggested that hospitals conducting psychosocial risk assessments of childbearing women consider reviewing their assessments in light of these findings.
Acknowledgements The principal author wishes to thank all staff and participants of the Hume Region Antenatal Risk Assessment Project.
References Astbury J, Brown S, Lumley J, Small R. (1994). Birth events, birth experiences and social differences in postnatal depression. Australian Journal of Public Health. 18(2): 176-84. Beck CT. (2001). Predictors of postpartum depression: an update. Nursing Research. Sept/Oct. Vol 50, No. 5: 275-285. Boyce E Stubbs J, Todd A. (t993). The Edinburgh Postnatal Depression Scale: Validation for an Australian sample. Australian and New Zealand Journal of Psychiatry. 27(3): 472-476. Brown S, Darcy MA, Bruinsma E (2001). Victorian Survey of Recent Mothers 2000. Report 3. Early postnatal care. Melbourne: Centre for the Study of Mothers' and Children's Health. Brown S, Lumley J, Small R, Astbury J. (1994). Missing Voices: the experience of motherhood. Melbourne: Oxford University Press. Buist A. (1995). Recognition and management of postnatal depression. Modern Medicine of Australia. March. 72-75. Cooper PJ, Murray L, Hooper R, West A. (1996). The development and validation of a predictive index for postpartum depression. Psychological Medicine. 26: 627-634. Cox JL, Holden MJ, Sagovsky R. (1987). Detection of postnatal depression. Development of the 10 item Edinburgh Postnatal Depression Scale. British Journal of Psychiatry. 150: 78~786. Nielsen FD, Videbech P, Hedegaard M, Salvig JD, Secher NJ. (2000). Postpartum depression: identification of women at risk. British Journal of Obstetrics and Gynaecology. 107: 1210-1217. Queensland Health. (2000) Initiative to combat the health impact of domestic violence against women. Stage 1 Evaluation Report. Webster J, Linnane JWJ, Dibley LM, Pritchard M. (2000). Improving antenatal recognition of women at risk of postnatal depression. Australian and New Zealand Journal of Obstetrics and Gynaecology. 10: 409-412. Webster J, Pritchard MA, Creedy D, East C. (2003). A simplified predictive index for the detection of women at risk for postnatal depression. Birth. 30(2) June: 101-108. Wilson LM, Reid AJ, Midmer DK, Biringer A, Carroll JC, Stewart DE . (1996) Antenatal psychosocial risk factors associated with adverse postpartum family outcomes. Canadian Medical Association Journal. 154: 785-799. Willinck L. (2000) Incidence of postnatal depression in Albury: a retrospective study of Early Child Health Nurse EPDS data. (unpublished).
Table 4 Logistic regression of risk factors for postnatal depression Risk c a t e g o r y
Risk factor
Antenatal
Perinatal
Regression coefficient
Wald
Odds ratio
p value
Domestic violence
1.79
3.02
6.02
0.082
Relationship problems
I. 15
1.72
3.16
0.190
Antenatal depression
1.86
I 1.43
6.46
0.00 I
Limited supports
0.47
0.50
1.60
0.478
Financial difficulties
0.72
0.82
2.05
0.366
History of postnatal depression
0.95
1.74
2.58
0.188
Recent stressful life events
-0.05
0.01
0.95
0.934
Severe highs or blues
4.19
9.18
66.37
0.002
No partner or support person at birth
1.59
1.34
4.91
0.246
1.93
4.99
6.90
0.025
-4.04
89,87
0.018
< 0.001
Dissatisfaction with care in labour and/or no say in decisions Constant
Australian Midwifery: Journal of the Australian College of MidwivesJune 2004
15
Risk factors for postnatal depression Lizette A Willinck and Susan M Cotton
ABSTRACT A prospective longitudinal study of 620 women investigated the association between a range of risk factors and postnatal depression (PND). Univariate analyses of results demonstrated seven antenatal and three perinatal variables significantly associated with PND. Antenatal risk factors included relationship problems, antenatal depression and limited supports. These factors had previously been reported in the literature. Additionally this study highlighted the significance of domestic violence as a risk factor. Perinatal factors significantly associated with PND were severe blues/highs, no partner or support person at birth and dissatisfaction with care in labour. Logistic regression analysis of the 10 combined antenatal and perinatal risk factors demonstrated that only three factors were found to be significant predictors of depression in the final model. These were antenatal depression, severe blues/highs and dissatisfaction with care in labour. With these variables in the regression equation, none of the other risk factors were contributing significantly to the prediction of PND.
Introduction Lowered mood, labile mood, tearfulness, irritability, anxiety, panic attacks and suicidal i d e a s . . , these are just some of the well-recognised symptoms of postnatal depression (Buist 1995). Although approximately 14% of childbearing Australian women experience postnatal depression (Brown et al. 2001), progress towards reducing this condition has been slow. One of the reasons is a difficulty in identifying Correspondence to LizetteA Willinck B App Sc (Speech Pathology) Research Project Coordinator PO Box 326 Albury NSW 2640 email [email protected] Susan M Cotton BBSc (hons), Grad Dip App Sc (statistics), M App Sc (statistics) Biostatistician Dept. Psychiatry University of Melbourne
10
AustralianMidwifery:Journal of the Australian College of Midwives June 2004
women who may be at risk. Risk factors for PND are many and varied. Factors linked to PND may present at varying stages of the pregnancy to parenthood continuum. This continuum of risk factors can arguably be grouped into four categories; antenatal risk factors, birth risk factors, immediate postpartum risk factors and postnatal risk factors. Despite the vast literature on risk factors for PND, most studies have focused simply on factors within specific risk categories, such as considering only antenatal risk factors. This has limited the scope of findings. Three major studies focused exclusively on antenatal risk factors for PND. Wilson et al (1996) conducted a comprehensive review of antenatal risk factors for PND and identified three antenatal psychosocial risk factors that had good evidence of an association with PND. These factors were relationship problems, recent stressful life events and antenatal depression. A further three factors found to have fair evidence of an association with PND were lack of social support, domestic violence and current/past psychiatric history. In the same year Cooper et al (1996) recruited a sample of over 6000 pregnant British women and administered a questionnaire to detect the presence of factors likely to increase risk of PND. Unfortunately the antenatal risk factors found to contribute most significantly to the development of PND were not specified. A study of 574 Australian women conducted by Webster et al. (2000) found three antenatal risk factors significantly linked to PND. These were low social support, psychiatric history and history of PND. Unfortunately the study omitted antenatal depression and recent stressful life events; two potential risk factors found by Wilson et al. (1996) to be of greatest significance. Only one major study has investigated associations between PND and birth and immediate postpartum risk factors. This study by Astbury et al. (1994) of 790 Victorian women found six factors associated with increased odds of depression in the final logistic model. These risk factors were; having a first child over the age of 34, assisted delivery, bottle feeding, dissatisfaction with antenatal care, unwanted people at the birth and lacking confidence to look after the baby at the time of leaving hospital. Although a small number of antenatally-evidenced 'social factors' were included in the study, most antenatal psychosocial risk factors mentioned in previously cited investigations were omitted. Two studies have attempted to investigate a range of antenatal, birth and immediate postpartum risk factors. Nielsen et al. (2000) tested the predictive power of a range of demographic, obstetric and psychosocial PND risk factors in a sample of 5252 women. Risk factors identified by multivariate logistic regression analysis as being significantly associated with PND were psychological distress in late pregnancy, social isolation, high parity and previous psychiatric history. However, several risk factors identified as significant in previous studies were not investigated. These
Lizette Willinck and Susan Cotton included relationship problems, domestic violence and dissatisfaction with care in labour. A recent Australian study by Webster (2003) screened 1762 women for 11 antenatal risk factors and 10 birth/immediate postpartum risk factors. Individual antenatal risk factors shown to be statistically associated with PND were past psychiatric history, family history of mood disorder, having a mother who had PND, low family support and conflict with partner. Individual postnatal risk factors shown to be statistically associated with PND were low satisfaction with delivery, low postnatal support and reduced parent-child interaction. Multivariate analysis was not conducted and unfortunately antenatal depression was not included as an antenatal risk factor. One study has attempted to investigate PND risk factors from the entire pregnancy to postnatal continuum, but this otherwise rigorous meta-analysis by Beck (2001) investigated only a relatively small number of risk factors (a total of 10 antenatal, two immediate postpartum, one postnatal and no birth risk factors). Selection criteria for the risk factors chosen was not specified. In conclusion, there has been a tendency for previous studies to either ignore the continuum of antenatal to postnatal risk factors for PND or to omit significant individual risk factors. The aim of this study was therefore twofold. The first aim was to include the spectrum of antenatal to birth and immediate postpartum risk categories. The second aim was to include all individual risk factors that had been deemed significant by a majority of previous studies and could be readily assessed for in a clinical setting. This led to a total of 15 antenatal risk factors, seven birth and six immediate postpartum risk factors for PND. Investigation of postnatal risk factors such as infant temperament could not be included in this study due to time frame and budgetary restrictions. This study formed part of a larger initiative, the three-year Hume Region Antenatal Risk Assessment Project, which aimed to better identify and assist not only women at risk of postnatal depression, but all psychosocially vulnerable pregnant women.
Methods In August 2000 a prospective longitudinal study of a single cohort of women recruited from five Maternity Hospitals in the Hume Region of north east Victoria commenced. The hospitals involved were Wodonga Regional Health Service, Goulburn Valley Hospital, Wangaratta District Base
Hospital, Seymour and District Memorial Hospital and Alpine Health. Funding was provided by the Hume Region Department of Human Services Maternity Services Enhancement Strategy and approval to conduct the study was obtained from the Victorian Department of Human Services Ethics Committee. Women consenting to participate in the study were screened with the following instruments:
Maternity Psychosocial Risk Assessment Tool (M PRAT) This tool was developed for the Hume Region Antenatal Risk Assessment Project and administered by midwives trained in its use. It consisted of an antenatal and a postnatal component. The antenatal component took approximately 45 minutes to administer. It contained probes to determine the presence/absence of 15 risk factors for PND that had been determined following extensive literature review. Risk factors included domestic violence, which was screened for with four questions pertaining to physical or emotional abuse over the past year. These questions had been developed by the Initiative to Combat the Health Impact of Domestic Violence Against Women (Queensland Health 2000). The postnatal component of the MPRAT was completed two to three days postnatally and took approximately 15 minutes to administer. It contained probes to determine the presence/absence of seven birth and six immediate postpartum risk factors for PND (referred to collectively as perinatal risk factors).
Edinburgh Postnatal Depression Scale (Cox et al. 1987) The Edinburgh Postnatal Depression Scale (EPDS) is one of the most widely used PND screening scales in Australia. It has been validated for use in Australia (Boyce et al. 1993) and is the only self-report scale that has been validated for use antenatally and postnatally. As with all screening tools, the scale cannot in itself confirm a diagnosis of PND, however a score of 10-12 is widely used to indicate possibility of minor depression and a score of greater than 12 indicates significant or major depression is likely. Participants were investigated on the following three occasions: 1. During second or third trimester of pregnancy. Administration of the antenatal component of the
Table I Demographic variables for postnatal depression Demographic variable
Parity Age
M (SD) M (SD)
Marital status
Married De facto Single
No P N D (EPD$ ~ 12)
PND (EPDS > 12)
0.86 (I. 12) 29.3 (5.5)
0.92 (I. 19) 29.2 (7.2)
%(n)
p value
1,79*
0.94* 0.001 #
75. I (250) 15.9 (53) 9.0 (30)
40 (I 0) 40 (10) 20 (5)
*p values from independent groups t-tests; #p values from chi square test Australian Midwifery: Journal of the Australian College of Midwives June 2004
II
Australian Midwifery: Journal of The Australian College of Midwives T a b l e 2 Antenatal risk factors for postnatal depression
Antenatal risk factor No P N D Domestic violence
Relationship problems
Antenatal depression
Late/limited antenatal care
Limited supports
Financial difficulties
History of postnatal depression
Recent significant stressful life events
Poor relationships with parents
(EPDS ~ 12) P N D
History of childhood abuse
Single parent
Other psychological/ psychiatric history Unwanted pregnancy
Born overseas NESB
Odds ratio
p value*
20.56
< 0.00 I
9.98
< 0.00 I
8.58
< 0.00 I
6.89
0.07
4.95
< 0.00 I
4.64
0.003
4.13
0.006
3.18
0.005
2.89
0.09
2.89
0.098
2.70
O. 12
2.69
0.08 I
2.37
0.06
N/A
0.784
N/A
0.78
1.2%
20%
(n = 4)
(n = 5
4.5%
32.0%
( n = 15)
(n=8)
12.9%
56.0%
(n = 43)
(n = 14)
0.6%
4.0%
(n = 2)
(n = I)
10.2%
36.0%
(n = 34)
(n = 9)
45. 1%
20.0%
( n = 17)
(n=5)
5.7%
20.0%
(n-- 19)
(n=5)
19.8%
44.0%
(n = 66)
(n = II)
4.5% ( n = 15)
Age less than 20 years
(EPDS > 12)
12.0% (n=3)
4.5%
12.0%
(n = 15)
(n = 3)
4.8%
12.0%
(n= 16)
(n--3)
6.6%
16.0%
(n = 22)
(n = 4)
14. 1%
28.0%
(n = 47)
(n = 7)
0.3%
0.0%
(n = I)
(n = 0)
0.3%
0.0%
(n = I)
(n = 0)
*p values obtained from chi square analyses with df = I N/A statistics such as chi square and the odds ratio not calculated due to null cells
12
AustralianMidwifery: Journal of the Australian College of MidwivesJune 2004
Lizette Willinck and Susan Cotton
MPRAT, including EPDS.Two to three days post natally. 2. Administration of the postnatal component of the MPRAT. 3. Six to eight weeks postnatally. Administration of the EPDS by Early/Maternal and Child Health Nurses (E/MCHNs). Data were analysed using the Statistical Package for Social Sciences (SPSS version 11.0.05). Chi square tests were used to assess associations between PND and categorical risk factors. For these univariate analyses alpha was set at 0.01 to reduce the chances of type I error. Odds ratios were used to provide a measure of association between two values and an index of relative risk. Logistic regression was used to determine which variables predicted PND.
Results A total of 734 pregnant women attending antenatal bookings at the five Hume Region hospitals were asked to participate in the study. Of the women, 620 agreed to participate, representing a consent rate of 84%. Of the women who participated, only 58% (358/620) were screened for PND at their six to eight week E/MCHN postnatal visit. Reasons for poor compliance with the postnatal EPDS screening were inability to screen due to conflict with another study (14%), women not locatable (13%), failure to attend appointment (8%), not screened by E/MCHN (6%) and refusal to be screened (1%). Women that were assessed postnatally with the EPDS were divided into two groups according to EPDS scores: no PND (EPDS score 12 or less) and PND (EPDS score greater than 12). Seven per cent of screened women (25/358) scored greater than 12, indicating probable major PND. Although it is recognised that an EPDS score of greater than 12 is merely indicative of depressive symptoms, for the purposes of this report women scoring in this category will henceforth be referred to as having PND.
Demographic variables associated with P N D Several demographic variables were examined with regards to PND (Table 1). Women in the PND versus no PND groups were similar in terms of parity and mean age but differed in terms of marital status. Single and defacto women were significantly more likely to develop PND than married women, X22 = 14.48, p = 0.001.
Antenatal risk factors associated with P N D Table 2 comprises the percentages of women with and without PND with each of the 15 antenatal risk factors. Seven antenatal variables were significantly associated with PND. Domestic violence, relationship problems and antenatal depression yielded the highest odds ratios, indicating that these were the most important risk factors for developing PND. For example, women who had experienced domestic violence in the past year were 20 times at greater risk for developing PND than women who had not experienced domestic violence.
Perinatal risk factors associated with P N D Birth and immediate postpartum risk factors were collectively termed perinatal risk factors. Table 3 comprises the percentages of women with and without PND with each of the perinatal risk factors. Three factors were significantly associated with PND. These were severe blues or highs, no partner or support person at birth and dissatisfaction with labour. Women who had experienced severe blues or highs were almost 29 times more likely to have PND than women who did not experience severe mood swings.
Multivariate analysis of risk factors associated with P N D A standard logistic regression was conducted to determine which antenatal and perinatal risk factors best predicted PND and to determine the model of best fit. See Table 4. All significant risk factors from the chi-square analyses were entered into the logistic regression equation. A test of the full model with 10 predictors against a constant only model was statistically significant, chi square X210 = 58.67, p < 0.001, with a considerable amount of the variance in PND being explained by the predictors, Nagelkerke R 2 -- .38. Only three were found to be significant predictors of depression in the final model. These were antenatal depression, severe blues or highs and dissatisfaction with care in labour. With these variables in the regression equation, none of the other risk factors were contributing significantly to the prediction of PND.
Discussion This study aimed to determine the relationship between a range of antenatal and perinatal risk factors and PND. Results indicated some important risk factors requiring further investigation and also yielded interesting data on incidence of PND in a regional/rural area. Only 7% of the women in the final sample screened positive for major PND. This figure was comparable to an earlier unpublished local study of Albury women (Willinck 2000) in which 6% of women screened (n = 406) were found to have major PND. It was also comparable to a large Danish study (Nielsen et al 2000) in which 5.5% of women examined (n = 5252) developed PND. However it was considerably lower than many other studies including the latest Victorian Survey of Recent Mothers in which incidence of PND was 14% (Brown et al. 2001). There are several possible explanations for the lower than expected incidence of PND in this study. One methodological factor for consideration is that the Survey of Recent Mothers was based on EPDS screening conducted eight to nine months postnatally, compared with the six to eight week postnatal time frame in this study. Another factor for consideration is the 42% attrition rate. Posthoc analyses indicated that a disproportionate number of the women lost to the study had antenatal risk factors for depression. Had they been included in the final sample the overall incidence of PND may have been higher. A final explanation is that incidence of PND may be lower in rural/regional areas. Australian Midwifery: Journal of the Australian College of Midwives June 2004
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Australian Midwifery: Journal of The Australian College of Midwives
T a b l e 3 Perinatal risk factors f o r postnatal depression
(EPDS < 12) P N D
(EPS > 12)
Odds ratio
p value*
0.3%
8.0%
28.87
< 0.001
(n = I)
(n = 2)
0.3%
4.0%
13.83
0.017
(n = I)
(n = I)
0.9%
8.0%
9.56
0.004
(n = 3)
(n = 2)
2.7%
16.0%
6.86
0.001
(n = 9)
(n -- 4)
Lack of parent skills or lack of
2.7%
8%
3.13
0.140
confidence to look after baby
(n = 9)
(n = 2)
5.4%
8.0%
1.52
0.590
(n = 18)
(n = 2)
15.6%
20.0%
1.35
0.560
(n = 52)
(n = 5)
4.8%
4.0%
0.83
0.850
( n = 16)
( n = I)
21.6%
16.0%
0.69
0.510
(n = 72)
(n = 4)
0.3%
0.0
N/A
0.780
(n = I)
(n = O)
0.3%
0.0%
N/A
0.780
(n = I)
(n = 0)
2.1%
0.0%
N/A
0.460
(n = 7)
(n = 0)
1.2%
0.0%
N/A
0.532
(n = 4)
(n = 0)
Perinatal risk f a c t o r N o P N D
Severe blues or high
Unwanted people at births
No partner or support person at birth
Dissatisfied with care in labour a n d / o r no say in decisions
Late birth complications or health problems
Problems with baby or significant feeding problems
Premature or post mature births
Birth not to plan including assisted birth or significant complications
Multiple births
Negative neutral feelings about baby or detatchment from baby
Early discharge from hospital not by patient choice
No partner or other support person after discharge
*p values obtained from chi square analyses with df = I N/A statistics such as chi square and the odds ratio not calculated due to null cells
14
AustralianMidwifery:Journalof the AustralianCollegeof MidwivesJune2004
Lizette Willinck and Susan Cotton
This suggestion is supported by a finding from the 1989 Victorian Survey of Recent Mothers, which indicated that lower odds of depression were significantly associated with non-metropolitan residence (Astbury et al 1994). Interestingly this finding was not replicated in the 2000 Survey of Recent Mothers (Brown et al. 2001). Chi square tests of the associations between antenatal risk factors and PND supported previous findings regarding the strong links between PND and relationship problems, antenatal depression, limited supports, history of PND and significant stressful life events (Wilson et al. 1996, Beck 2001). However it also found that the antenatal risk factor with the highest odds ratio was domestic violence. Although this finding needs to be treated with caution due to the small sample size it is of interest given it was a factor excluded by many authors (Astbury et al. 1994, Cooper et al. 1996, Nielsen et al. 2000, Beck 2001). Webster et al. (2000, 2003) arguably included potential indicators of domestic violence in their 'conflict with partner' and 'controlled by partner' risk factors, but they did not report these factors as being significantly associated with PND. Published studies on the relationships between perinatal risk factors and PND are limited. Therefore the chi square analyses conducted in this study are a useful contribution to the literature. The results from this study support previous findings that severe blues or highs (Beck 2001, Webster et al. 2003), no partner or support person at birth (Astbury et al. 1994) and dissatisfaction with care in labour (Webster 2003) are all significantly associated with PND. Multivariate analysis conducted with this data suggest that in the final model only three risk factors were significant predictors of PND. However, these results should be treated with particular caution due to the sample size. Investigation of the associations between PND and protective or resilience factors was outside the scope of this study. However, further studies into the role of high self esteem, good social supports and other protective factors would be welcome contributions to the literature. In conclusion, this study indicates that future research into risk factors for PND should include a range of antenatal, birth, immediate postpartum and, where possible, postnatal
risk factors for PND, with consideration also being given to the role of protective factors. The importance of including antenatal depression , domestic violence, dissatisfaction with care in labour and severe blues/highs as risk factors is emphasised. It is also suggested that hospitals conducting psychosocial risk assessments of childbearing women consider reviewing their assessments in light of these findings.
Acknowledgements The principal author wishes to thank all staff and participants of the Hume Region Antenatal Risk Assessment Project.
References Astbury J, Brown S, Lumley J, Small R. (1994). Birth events, birth experiences and social differences in postnatal depression. Australian Journal of Public Health. 18(2): 176-84. Beck CT. (2001). Predictors of postpartum depression: an update. Nursing Research. Sept/Oct. Vol 50, No. 5: 275-285. Boyce E Stubbs J, Todd A. (t993). The Edinburgh Postnatal Depression Scale: Validation for an Australian sample. Australian and New Zealand Journal of Psychiatry. 27(3): 472-476. Brown S, Darcy MA, Bruinsma E (2001). Victorian Survey of Recent Mothers 2000. Report 3. Early postnatal care. Melbourne: Centre for the Study of Mothers' and Children's Health. Brown S, Lumley J, Small R, Astbury J. (1994). Missing Voices: the experience of motherhood. Melbourne: Oxford University Press. Buist A. (1995). Recognition and management of postnatal depression. Modern Medicine of Australia. March. 72-75. Cooper PJ, Murray L, Hooper R, West A. (1996). The development and validation of a predictive index for postpartum depression. Psychological Medicine. 26: 627-634. Cox JL, Holden MJ, Sagovsky R. (1987). Detection of postnatal depression. Development of the 10 item Edinburgh Postnatal Depression Scale. British Journal of Psychiatry. 150: 78~786. Nielsen FD, Videbech P, Hedegaard M, Salvig JD, Secher NJ. (2000). Postpartum depression: identification of women at risk. British Journal of Obstetrics and Gynaecology. 107: 1210-1217. Queensland Health. (2000) Initiative to combat the health impact of domestic violence against women. Stage 1 Evaluation Report. Webster J, Linnane JWJ, Dibley LM, Pritchard M. (2000). Improving antenatal recognition of women at risk of postnatal depression. Australian and New Zealand Journal of Obstetrics and Gynaecology. 10: 409-412. Webster J, Pritchard MA, Creedy D, East C. (2003). A simplified predictive index for the detection of women at risk for postnatal depression. Birth. 30(2) June: 101-108. Wilson LM, Reid AJ, Midmer DK, Biringer A, Carroll JC, Stewart DE . (1996) Antenatal psychosocial risk factors associated with adverse postpartum family outcomes. Canadian Medical Association Journal. 154: 785-799. Willinck L. (2000) Incidence of postnatal depression in Albury: a retrospective study of Early Child Health Nurse EPDS data. (unpublished).
Table 4 Logistic regression of risk factors for postnatal depression Risk c a t e g o r y
Risk factor
Antenatal
Perinatal
Regression coefficient
Wald
Odds ratio
p value
Domestic violence
1.79
3.02
6.02
0.082
Relationship problems
I. 15
1.72
3.16
0.190
Antenatal depression
1.86
I 1.43
6.46
0.00 I
Limited supports
0.47
0.50
1.60
0.478
Financial difficulties
0.72
0.82
2.05
0.366
History of postnatal depression
0.95
1.74
2.58
0.188
Recent stressful life events
-0.05
0.01
0.95
0.934
Severe highs or blues
4.19
9.18
66.37
0.002
No partner or support person at birth
1.59
1.34
4.91
0.246
1.93
4.99
6.90
0.025
-4.04
89,87
0.018
< 0.001
Dissatisfaction with care in labour and/or no say in decisions Constant
Australian Midwifery: Journal of the Australian College of MidwivesJune 2004
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