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Associations between poor subjective prenatal sleep quality and postnatal depression and anxiety symptoms
Journal of Affective Disorders 202 (2016) 91–94
Contents lists available at ScienceDirect
Journal of Affective Disorders journal homepage: www.elsevier.com/locate/jad
Associations between poor subjective prenatal sleep quality and postnatal depression and anxiety symptoms Elaine K.H. Tham a, Joyce Tan b, Yap.-Seng. Chong a,c, Kenneth Kwek d, Seang.-Mai. Saw b,e,f, Oon.-Hoe. Teoh d, Daniel Y.T Goh g, Michael J. Meaney a,h, Birit F.P. Broekman a,b,n a
Singapore Institute for Clinical Sciences, Agency for Science and Technology Research (AnSTAR), Brenner Centre for Molecular Medicine, Singapore Department of Psychological Medicine, Yong Loo Lin School of Medicine, National University of Singapore, National University Health System, Singapore c Department of Obstetrics & Gynaecology, Yong Loo Lin School of Medicine, National University of Singapore, National University Health System, Singapore d KK Women's and Children's Hospital, Singapore e Saw Swee Hock School of Public Health, National University of Singapore, Singapore f Singapore Eye Research Institute, Singapore National Eye Centre, Singapore g Department of Pediatrics, Yong Loo Lin School of Medicine, National University of Singapore, National University Health System, Singapore h Douglas Mental Health University Institute, McGill University, Canada b
art ic l e i nf o
a b s t r a c t
Article history: Received 15 December 2015 Received in revised form 18 May 2016 Accepted 18 May 2016 Available online 25 May 2016
Background: Symptoms of depression and anxiety are common during pregnancy and the postnatal period. A risk factor for mood disorders is poor sleep quality. In this study we investigate the effects of poor subjective prenatal sleep quality on postnatal depressive and anxiety symptoms, independent of prenatal depression or anxiety, amongst pregnant women in the general population. Methods: We analysed data from a subset of women taking part in a prospective cohort study, Growing Up in Singapore towards Healthy Outcomes. The participants completed the Edinburgh Postnatal Depression Scale and State-Trait Anxiety Inventory between 26 and 28 weeks of pregnancy (Time 1) and at 3 months postpartum (Time 2), and the Pittsburgh Sleep Quality Index at Time 1. Logistic regression analyses were used to investigate the associations between subjective prenatal sleep quality and postnatal depressive and anxiety symptoms, while adjusting for prenatal depressive/anxiety symptoms and education. Results: Although borderline-high depressive/anxiety symptoms were the strongest predictors of postnatal depressive/anxiety, independent of this, poor subjective sleep quality during pregnancy was also associated with borderline-high postnatal depressive symptoms, but not with postnatal anxiety. Limitations: Sleep quality and prenatal/postnatal mood were derived from self-reported questionnaires, which may be more susceptible to bias. Conclusion: Although treatment of symptoms of prenatal depression and anxiety will be the most important for reducing postnatal depression and anxiety, in addition to that, future studies may explore treatments improving prenatal sleep quality, particularly for women with antenatal depressive symptoms. & 2016 Elsevier B.V. All rights reserved.
Keywords: Maternal sleep Depression Anxiety Pregnancy Mental health
1. Introduction Symptoms of depression and anxiety during the peri-partum period are common, with a global prevalence of up to 26% (Gotlib et al., 1989; Norhayati et al., 2015) and 30% (Britton, 2008) respectively, while prevalence rates of diagnoses of postnatal depressive or anxiety disorders is, respectively up to 13% and 8–11% (Gavin et al., 2005; Misri et al., 2015; Reck et al., 2008).
n Corresponding author at: Singapore Institute for Clinical Sciences, Agency for Science and Technology Research AnStar Brenner Centre for Molecular Medicine, Singapore.
http://dx.doi.org/10.1016/j.jad.2016.05.028 0165-0327/& 2016 Elsevier B.V. All rights reserved.
Importantly, these symptoms can have detrimental effects on neurodevelopment of the offspring, such as birth outcomes, and increased emotional and cognitive problems (Dunkel Schetter et al., 2012; Glover, 2014). Hence, prevention or treatment has potential effects on child outcomes. Experience of poor sleep quality is not only linked to depression and anxiety but also common in the peri-partum period, with a recent study reporting a prevalence of 60% of insomnia during pregnancy (Sivertsen et al., 2015). Women who received sleep medication for insomnia during the third trimester reported fewer depressive symptoms postnatally than those who did not receive treatment (Khazaie et al., 2013), suggesting a link between sleep quality during pregnancy and postnatal mood. Indeed, more
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recent studies found that subjective sleep quality during pregnancy was associated with (Skouteris et al., 2009) or had additive effects on postnatal depression (Bei et al., 2010; Wu et al., 2014). Although a few previous studies found that poor subjective prenatal sleep quality was also correlated with higher levels of postnatal anxiety (Skouteris et al., 2009; Swanson et al., 2011), a recent review found not enough evidence (Lawson et al., 2015). The present study extends previous work by investigating the effects of poor subjective prenatal sleep among pregnant Singaporean women in the general population on postnatal depressive and anxiety symptoms, beyond the influence of prenatal symptoms of mood and anxiety. In addition, this study examines mood in terms of symptom severity rather than clinical diagnoses, into two categories – borderline-high/high level versus low level. We hypothesize that poor subjective sleep quality during pregnancy will predict borderline-high/high levels of post-partum depression and anxiety, beyond the level of prenatal symptoms.
2. Method
sleep efficiency, sleep disturbances, use of sleeping medication and daytime dysfunction. A global measure of sleep quality is derived from the sum of the 7 measures (range 0–21), with higher scores representing poorer subjective sleep quality. A validated cutoff score of 6 was used (Backhaus et al., 2002), where scores Z7 denoted poor sleep quality. 2.3. Data analysis We conducted univariate ANOVAs to test if main sociodemographic factors were different between those who were included in our sample and those excluded. To check for covariates, we also ran univariate ANOVAs of sociodemographic variables on postnatal depression and anxiety. Kolmogorov-Smirnov tests indicated that PSQI, EPDS and STAI scores (all timepoints) were nonnormally distributed (all p's o.001), hence logistic regression analyses were performed using IBM SPSS 23.0 (SPSS Inc, Chicago, IL), with categorical levels of postnatal depressive/anxiety symptoms as dependent variables and subjective prenatal sleep quality as the independent variable, while adjusting for prenatal depression/anxiety and education (adjusted model).
2.1. Participants This study was part of the Growing Up in Singapore Towards healthy Outcomes (GUSTO), which recruited 1247 pregnant women in their first trimester, from two large birthing hospitals in Singapore (for study details see Soh et al., 2014). During the first recruitment hospital visit (o14 weeks of pregnancy) the participants were interviewed to obtain sociodemographic information, the self-report questionnaires were administered during follow-up visits between 26 and 28-weeks of pregnancy (Time 1) and at 3-months post-pregnancy (Time 2). We excluded mothers (n ¼368) with gestational diabetes, hypertension and preeclampsia, and those who smoked and consumed alcohol during pregnancy. Of the remaining participants, only 313 had complete longitudinal data on all questionnaires (n¼ 316 for sleep and depression analyses, n ¼320 for sleep and anxiety analyses), and were included in the final sample. The GUSTO study was approved by the National Health Care Group Domain Specific Review Board and the SingHealth Centralized Institutional Review Board. Written, informed consent was obtained from all participants. 2.2. Questionnaires 2.2.1. Edinburgh Postnatal Depression Scale (EPDS) The EPDS is a 10-items screening instrument to identify perinatal depression, with total scores ranging from 0 to 30. We used the borderline cut-off of 10 (Chen et al., 2011), with scores Z10 indicating a borderline to high probability of depressive disorder (Cox et al., 1987). 2.2.2. State-Trait Anxiety Inventory (STAI) The STAI measures symptom severity for both “state” and “trait” anxiety, referring respectively to levels of current anxiety symptoms and anxious personality traits (Spielberger et al., 1983). As this study is concerned with anxiety symptoms that women experienced at the point of assessment, we only explored state anxiety, which consists of 20 items on a 4-point Likert scale. The final score is a sum of all items. An established cutoff of 40 was used, with scores of r40 denoting low levels of symptoms, while scores of 440 denoting high levels of anxiety (Addolorato et al., 1999). 2.2.3. Pittsburgh Sleep Quality Index (PSQI) The PSQI (Buysse et al., 1989) has 7 measures of sleep quality: subjective sleep quality, sleep latency, sleep duration, habitual
3. Results 3.1. Sample characteristics In our study sample, women were of Chinese (51.4%), Malay (28.8%) or Indian (19.8%) ethnicity. Education was characterized into below primary (3%), primary (1.6%), secondary (19.2%), GCE A-levels or equivalent (37.5%), university degree (39.7%) and postgraduate degree (1.6%). Most women were married (96.7%). The mean age was 30.3 years (18–41, SD ¼5.02). There were no significant differences in participant characteristics such as age [F (1802) ¼1.21, p¼ .27], marital status [F (1802) ¼.005, p¼ .95] and ethnicity [F (1802) ¼.12, p ¼.73] for women with or without longitudinal data, with the exception of women with longitudinal data having significantly higher education [F (1802) ¼32.27, po .001]. Sociodemographic variables were not associated with both postnatal depression and anxiety (all p's 4.05), with the exception of education and postnatal anxiety [F (1299)¼ 9.35, p ¼.002]. At the prenatal time point, 29.7% of participants had poor subjective sleep quality (PSQI Z7, M ¼8.91, SD¼ 2.06), 28.8% met criteria for high depressive symptoms (EPDS Z10, M¼13.11, SD ¼3.28) and 25.2% for high anxiety symptoms (STAI 440, M¼47.86. SD ¼5.57). At the postnatal time point, 20.1% of participants met criteria for high depressive symptoms (EPDS Z10, M¼13.30, SD¼ 3.50) and 20.9% for high anxiety symptoms (STAI440, M ¼47.63, SD ¼ 5.76). In addition, 66.4% of participants with high depressive symptoms prenatally also had high anxiety symptoms, and 64.6% of participants with high depressive symptoms postnatally also had high anxiety symptoms. Due to the high comorbidity between depressive and anxiety symptoms, we did not control for prenatal anxiety symptoms (when postnatal depression was the outcome variable) and vice versa due to potential issues with collinearity. 3.2. Subjective prenatal sleep and postnatal depressive symptoms Logistic regression results in Table 1 revealed that in the unadjusted model, women with poor subjective prenatal sleep were 2.66 times (95% CI:1.52–4.68) more likely to have borderline-high postnatal depressive symptoms as compared to those who had good subjective sleep. In addition, in the adjusted model, women with borderline-
E.K.H. Tham et al. / Journal of Affective Disorders 202 (2016) 91–94
Table 1. Logistic regression analyses between subjective prenatal sleep quality and postnatal depressive symptoms. 95% CI for Odds Ratio Predictor
B (SE)
Lower
Odds Ratio
Upper
Unadjusted Model Prenatal PSQI Adjusted Model
.98*** (.29) .037 (.17)
1.52 .69
2.66 .96
4.68 1.36
Education Prenatal EPDS Prenatal PSQI
1.18*** (.31) .62* (.31)
1.76 1.01
3.24 1.85
5.99 3.40
Note: R2 ¼ .08 (Cox & Snell),.13 (Nagelkerke) for the adjusted model. *
p o .05. p o .001.
***
high prenatal depressive symptoms were 3.24 times (95% CI:1.76– 5.99) more likely to continue having borderline-high postnatal depressive symptoms compared to those who had low prenatal symptoms. In the adjusted model, we still found significant associations between sleep quality and postnatal depressive symptoms: women with poor subjective prenatal sleep were 1.85 times (95% CI:1.01–3.40) more likely to also have borderline-high postnatal depressive symptoms as compared to those who had good subjective sleep quality. 3.3. Subjective prenatal sleep and postnatal anxiety symptoms Logistic regression results in Table 2 revealed that in the unadjusted model, women with poor subjective prenatal sleep were 2.12 times (95% CI:1.21–3.70) more likely to have high postnatal anxiety symptoms as compared to those who had good subjective sleep. In addition, in the adjusted model, women with high anxiety symptoms during pregnancy were 6.18 times (95% CI:3.29–11.59) more likely to also have postnatal high anxiety symptoms as compared to those had low anxiety symptoms. In the adjusted model, there was no significant association between subjective prenatal sleep quality and postnatal anxiety symptoms.
4. Discussion Our findings show that poor subjective sleep quality during pregnancy was - independently from prenatal depressive symptoms - significantly associated with postnatal depressive Table 2. Logistic regression analyses between subjective prenatal sleep quality and postnatal anxiety symptoms. 95% CI for Odds Ratio Predictor
B (SE)
Lower
Odds Ratio
Unadjusted Model Prenatal PSQI Adjusted Model
.75** (.29) .047 (.17)
1.21 .67
2.12 .95
3.70 1.35
Education Prenatal STAI state Prenatal PSQI
1.82*** (.32) .28 (.32)
3.29 .71
6.18 1.32
11.59 2.46
Note: R2 ¼ .13 (Cox & Snell),.20 (Nagelkerke). ** ***
po .01. p o .001.
Upper
93
symptoms. In contrast, poor subjective prenatal sleep did not increase the odds of developing high postnatal anxiety symptoms after controlling for prenatal anxiety. Our findings are in concordance with the recent review of Lawson et al., 2015, who found an association between self-reported poor sleep and postnatal depression, but not anxiety. Although our findings showed that prenatal depression remained the strongest predictor of postnatal depression, these findings suggest that poor subjective prenatal sleep can be an extra risk factor for developing postnatal depression. It is possible that poor subjective sleep quality during pregnancy impacts coping after pregnancy, as women who perceive themselves as having poor sleep are also more likely to perceive themselves as having more postpartum stress (Bei et al., 2010; Roeser et al., 2012), thus in turn leading to increased symptoms of depression. Another criticism is that poor sleep is a common feature of depression (Skouteris et al., 2009), hence findings on postnatal depression may be driven solely by prenatal depression. However, in our study we found effects of poor subjective prenatal sleep while controlling for prenatal depression. Another possible pathway is that poor subjective prenatal sleep quality may relate to poor subjective postnatal sleep quality, which then leads to increased depressive symptoms. Even though poor subjective prenatal sleep is still involved in the above pathway, future studies should also investigate the potential role of postnatal sleep quality to gain more insights into the role of prenatal sleep on postnatal depression. The limited, but statistically significant, role of poor subjective prenatal sleep quality on the etiology of postnatal depressive symptoms suggest that, in addition to treatment of depression, treatment of sleep problems can be helpful (Haynes, 2015; Sutton, 2014). During pregnancy especially, non-pharmacological treatments could be considered such as sleep hygiene education, cognitive behavioral therapies and relaxation techniques (Haynes, 2015; Sutton, 2014). A strength of this study is that it replicates key findings from recent work focusing on depressive and anxiety symptoms among non-clinical samples (Bei et al., 2010; Skouteris et al., 2009; Swanson et al., 2011; Wu et al., 2014). Instead of excluding women with high symptoms (Wu et al., 2014), we used borderline cut-offs, as mild depressive and anxiety symptoms are more common in the general population. However, a limitation is the use of self-reported measurements, which may be subjective in nature. The association between sleep quality and perinatal mood has been reported to be stronger when subjective self-reported measures were used compared to objective measures (Bei et al., 2010). In addition, the study did not collect measures of sleep quality prior to pregnancy, hence we were not able to disentangle specific effects of sleep during pregnancy from participant's general sleep quality. Another limitation is that the women in our study were part of a larger study which may limit the generalizability of our findings due to selection bias. Although we used the same timepoints of measures during pregnancy (Bei et al., 2010; Wu et al., 2014) and postpartum (Wu et al., 2014) as other studies, the interpretation of our findings are only limited to these timepoints. Even though existing work has revealed that prevalence of maternal sleep problems is fairly stable from pregnancy up to 2 years postpartum (Sivertsen et al., 2015), it would be interesting for future studies to explore the relations between trajectories of sleep quality and depression/ anxiety during and after pregnancy to better predict causal pathways between peri-partum sleep and mood. In conclusion, poor subjective prenatal sleep quality increases the risk of postnatal depression but not anxiety, even after adjusting for the presence of prenatal symptoms. As prenatal depressive and anxiety symptoms were still the strongest predictors of postnatal depression and anxiety, treatment of depression and
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anxiety remain of utmost importance. Nonetheless, future studies may explore if treatments for sleep, such as sleep hygiene or relaxation techniques, may additionally help to reduce the risk for postnatal depression, in particular for women with antenatal borderline-high depressive symptoms.
Acknowledgements
(i) The GUSTO study group includes Pratibha Agarwal, Arijit Biswas, Choon Looi Bong, Birit F. P. Broekman, Shirong Cai, Jerry Kok Yen Chan, Yiong Huak Chan, Cornelia Yin Ing Chee, Helen Chen, Yin Bun Cheung, Audrey Chia, Amutha Chinnadurai, Chai Kiat Chng, Mary Foong-Fong Chong, Yap-Seng Chong, Shang Chee Chong, Mei Chien Chua, Eric Andrew Finkelstein, Doris Fok, Marielle V. Fortier, Peter D. Gluckman, Keith M. Godfrey, Anne Eng Neo Goh, Yam Thiam Daniel Goh, Joshua J. Gooley, Wee Meng Han, Mark Hanson, Christiani Jeyakumar Henry, Joanna D. Holbrook, Chin-Ying Hsu, Hazel Inskip, Jeevesh Kapur, Kenneth Kwek, Ivy Yee-Man Lau, Bee Wah Lee, Yung Seng Lee, Ngee Lek, Sok Bee Lim, Iliana Magiati, Lourdes Mary Daniel, Michael Meaney, Cheryl Ngo, Krishnamoorthy Niduvaje, Wei Wei Pang, Anqi Qiu, Boon Long Quah, Victor Samuel Rajadurai, Mary Rauff, Salome A. Rebello, Jenny L. Richmond, Anne Rifkin-Graboi, Seang-Mei Saw, Lynette Pei-Chi Shek, Allan Sheppard, Borys Shuter, Leher Singh, Shu-E Soh, Walter Stunkel, Lin Lin Su, Kok Hian Tan, Oon Hoe Teoh, Mya Thway Tint, Hugo P S van Bever, Rob M. van Dam, Inez Bik Yun Wong, P. C. Wong, Fabian Yap, George Seow Heong Yeo. (ii) This research is supported by the Singapore National Research Foundation under its Translational and Clinical Research (TCR) Flagship Programme and administered by the Singapore Ministry of Health's National Medical Research Council (NMRC), Singapore- NMRC/TCR/004-NUS/2008; NMRC/TCR/012-NUHS/ 2014. Additional funding is provided by the Singapore Institute for Clinical Sciences, Agency for Science Technology and Research (A*STAR), Singapore.
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Contents lists available at ScienceDirect
Journal of Affective Disorders journal homepage: www.elsevier.com/locate/jad
Associations between poor subjective prenatal sleep quality and postnatal depression and anxiety symptoms Elaine K.H. Tham a, Joyce Tan b, Yap.-Seng. Chong a,c, Kenneth Kwek d, Seang.-Mai. Saw b,e,f, Oon.-Hoe. Teoh d, Daniel Y.T Goh g, Michael J. Meaney a,h, Birit F.P. Broekman a,b,n a
Singapore Institute for Clinical Sciences, Agency for Science and Technology Research (AnSTAR), Brenner Centre for Molecular Medicine, Singapore Department of Psychological Medicine, Yong Loo Lin School of Medicine, National University of Singapore, National University Health System, Singapore c Department of Obstetrics & Gynaecology, Yong Loo Lin School of Medicine, National University of Singapore, National University Health System, Singapore d KK Women's and Children's Hospital, Singapore e Saw Swee Hock School of Public Health, National University of Singapore, Singapore f Singapore Eye Research Institute, Singapore National Eye Centre, Singapore g Department of Pediatrics, Yong Loo Lin School of Medicine, National University of Singapore, National University Health System, Singapore h Douglas Mental Health University Institute, McGill University, Canada b
art ic l e i nf o
a b s t r a c t
Article history: Received 15 December 2015 Received in revised form 18 May 2016 Accepted 18 May 2016 Available online 25 May 2016
Background: Symptoms of depression and anxiety are common during pregnancy and the postnatal period. A risk factor for mood disorders is poor sleep quality. In this study we investigate the effects of poor subjective prenatal sleep quality on postnatal depressive and anxiety symptoms, independent of prenatal depression or anxiety, amongst pregnant women in the general population. Methods: We analysed data from a subset of women taking part in a prospective cohort study, Growing Up in Singapore towards Healthy Outcomes. The participants completed the Edinburgh Postnatal Depression Scale and State-Trait Anxiety Inventory between 26 and 28 weeks of pregnancy (Time 1) and at 3 months postpartum (Time 2), and the Pittsburgh Sleep Quality Index at Time 1. Logistic regression analyses were used to investigate the associations between subjective prenatal sleep quality and postnatal depressive and anxiety symptoms, while adjusting for prenatal depressive/anxiety symptoms and education. Results: Although borderline-high depressive/anxiety symptoms were the strongest predictors of postnatal depressive/anxiety, independent of this, poor subjective sleep quality during pregnancy was also associated with borderline-high postnatal depressive symptoms, but not with postnatal anxiety. Limitations: Sleep quality and prenatal/postnatal mood were derived from self-reported questionnaires, which may be more susceptible to bias. Conclusion: Although treatment of symptoms of prenatal depression and anxiety will be the most important for reducing postnatal depression and anxiety, in addition to that, future studies may explore treatments improving prenatal sleep quality, particularly for women with antenatal depressive symptoms. & 2016 Elsevier B.V. All rights reserved.
Keywords: Maternal sleep Depression Anxiety Pregnancy Mental health
1. Introduction Symptoms of depression and anxiety during the peri-partum period are common, with a global prevalence of up to 26% (Gotlib et al., 1989; Norhayati et al., 2015) and 30% (Britton, 2008) respectively, while prevalence rates of diagnoses of postnatal depressive or anxiety disorders is, respectively up to 13% and 8–11% (Gavin et al., 2005; Misri et al., 2015; Reck et al., 2008).
n Corresponding author at: Singapore Institute for Clinical Sciences, Agency for Science and Technology Research AnStar Brenner Centre for Molecular Medicine, Singapore.
http://dx.doi.org/10.1016/j.jad.2016.05.028 0165-0327/& 2016 Elsevier B.V. All rights reserved.
Importantly, these symptoms can have detrimental effects on neurodevelopment of the offspring, such as birth outcomes, and increased emotional and cognitive problems (Dunkel Schetter et al., 2012; Glover, 2014). Hence, prevention or treatment has potential effects on child outcomes. Experience of poor sleep quality is not only linked to depression and anxiety but also common in the peri-partum period, with a recent study reporting a prevalence of 60% of insomnia during pregnancy (Sivertsen et al., 2015). Women who received sleep medication for insomnia during the third trimester reported fewer depressive symptoms postnatally than those who did not receive treatment (Khazaie et al., 2013), suggesting a link between sleep quality during pregnancy and postnatal mood. Indeed, more
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recent studies found that subjective sleep quality during pregnancy was associated with (Skouteris et al., 2009) or had additive effects on postnatal depression (Bei et al., 2010; Wu et al., 2014). Although a few previous studies found that poor subjective prenatal sleep quality was also correlated with higher levels of postnatal anxiety (Skouteris et al., 2009; Swanson et al., 2011), a recent review found not enough evidence (Lawson et al., 2015). The present study extends previous work by investigating the effects of poor subjective prenatal sleep among pregnant Singaporean women in the general population on postnatal depressive and anxiety symptoms, beyond the influence of prenatal symptoms of mood and anxiety. In addition, this study examines mood in terms of symptom severity rather than clinical diagnoses, into two categories – borderline-high/high level versus low level. We hypothesize that poor subjective sleep quality during pregnancy will predict borderline-high/high levels of post-partum depression and anxiety, beyond the level of prenatal symptoms.
2. Method
sleep efficiency, sleep disturbances, use of sleeping medication and daytime dysfunction. A global measure of sleep quality is derived from the sum of the 7 measures (range 0–21), with higher scores representing poorer subjective sleep quality. A validated cutoff score of 6 was used (Backhaus et al., 2002), where scores Z7 denoted poor sleep quality. 2.3. Data analysis We conducted univariate ANOVAs to test if main sociodemographic factors were different between those who were included in our sample and those excluded. To check for covariates, we also ran univariate ANOVAs of sociodemographic variables on postnatal depression and anxiety. Kolmogorov-Smirnov tests indicated that PSQI, EPDS and STAI scores (all timepoints) were nonnormally distributed (all p's o.001), hence logistic regression analyses were performed using IBM SPSS 23.0 (SPSS Inc, Chicago, IL), with categorical levels of postnatal depressive/anxiety symptoms as dependent variables and subjective prenatal sleep quality as the independent variable, while adjusting for prenatal depression/anxiety and education (adjusted model).
2.1. Participants This study was part of the Growing Up in Singapore Towards healthy Outcomes (GUSTO), which recruited 1247 pregnant women in their first trimester, from two large birthing hospitals in Singapore (for study details see Soh et al., 2014). During the first recruitment hospital visit (o14 weeks of pregnancy) the participants were interviewed to obtain sociodemographic information, the self-report questionnaires were administered during follow-up visits between 26 and 28-weeks of pregnancy (Time 1) and at 3-months post-pregnancy (Time 2). We excluded mothers (n ¼368) with gestational diabetes, hypertension and preeclampsia, and those who smoked and consumed alcohol during pregnancy. Of the remaining participants, only 313 had complete longitudinal data on all questionnaires (n¼ 316 for sleep and depression analyses, n ¼320 for sleep and anxiety analyses), and were included in the final sample. The GUSTO study was approved by the National Health Care Group Domain Specific Review Board and the SingHealth Centralized Institutional Review Board. Written, informed consent was obtained from all participants. 2.2. Questionnaires 2.2.1. Edinburgh Postnatal Depression Scale (EPDS) The EPDS is a 10-items screening instrument to identify perinatal depression, with total scores ranging from 0 to 30. We used the borderline cut-off of 10 (Chen et al., 2011), with scores Z10 indicating a borderline to high probability of depressive disorder (Cox et al., 1987). 2.2.2. State-Trait Anxiety Inventory (STAI) The STAI measures symptom severity for both “state” and “trait” anxiety, referring respectively to levels of current anxiety symptoms and anxious personality traits (Spielberger et al., 1983). As this study is concerned with anxiety symptoms that women experienced at the point of assessment, we only explored state anxiety, which consists of 20 items on a 4-point Likert scale. The final score is a sum of all items. An established cutoff of 40 was used, with scores of r40 denoting low levels of symptoms, while scores of 440 denoting high levels of anxiety (Addolorato et al., 1999). 2.2.3. Pittsburgh Sleep Quality Index (PSQI) The PSQI (Buysse et al., 1989) has 7 measures of sleep quality: subjective sleep quality, sleep latency, sleep duration, habitual
3. Results 3.1. Sample characteristics In our study sample, women were of Chinese (51.4%), Malay (28.8%) or Indian (19.8%) ethnicity. Education was characterized into below primary (3%), primary (1.6%), secondary (19.2%), GCE A-levels or equivalent (37.5%), university degree (39.7%) and postgraduate degree (1.6%). Most women were married (96.7%). The mean age was 30.3 years (18–41, SD ¼5.02). There were no significant differences in participant characteristics such as age [F (1802) ¼1.21, p¼ .27], marital status [F (1802) ¼.005, p¼ .95] and ethnicity [F (1802) ¼.12, p ¼.73] for women with or without longitudinal data, with the exception of women with longitudinal data having significantly higher education [F (1802) ¼32.27, po .001]. Sociodemographic variables were not associated with both postnatal depression and anxiety (all p's 4.05), with the exception of education and postnatal anxiety [F (1299)¼ 9.35, p ¼.002]. At the prenatal time point, 29.7% of participants had poor subjective sleep quality (PSQI Z7, M ¼8.91, SD¼ 2.06), 28.8% met criteria for high depressive symptoms (EPDS Z10, M¼13.11, SD ¼3.28) and 25.2% for high anxiety symptoms (STAI 440, M¼47.86. SD ¼5.57). At the postnatal time point, 20.1% of participants met criteria for high depressive symptoms (EPDS Z10, M¼13.30, SD¼ 3.50) and 20.9% for high anxiety symptoms (STAI440, M ¼47.63, SD ¼ 5.76). In addition, 66.4% of participants with high depressive symptoms prenatally also had high anxiety symptoms, and 64.6% of participants with high depressive symptoms postnatally also had high anxiety symptoms. Due to the high comorbidity between depressive and anxiety symptoms, we did not control for prenatal anxiety symptoms (when postnatal depression was the outcome variable) and vice versa due to potential issues with collinearity. 3.2. Subjective prenatal sleep and postnatal depressive symptoms Logistic regression results in Table 1 revealed that in the unadjusted model, women with poor subjective prenatal sleep were 2.66 times (95% CI:1.52–4.68) more likely to have borderline-high postnatal depressive symptoms as compared to those who had good subjective sleep. In addition, in the adjusted model, women with borderline-
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Table 1. Logistic regression analyses between subjective prenatal sleep quality and postnatal depressive symptoms. 95% CI for Odds Ratio Predictor
B (SE)
Lower
Odds Ratio
Upper
Unadjusted Model Prenatal PSQI Adjusted Model
.98*** (.29) .037 (.17)
1.52 .69
2.66 .96
4.68 1.36
Education Prenatal EPDS Prenatal PSQI
1.18*** (.31) .62* (.31)
1.76 1.01
3.24 1.85
5.99 3.40
Note: R2 ¼ .08 (Cox & Snell),.13 (Nagelkerke) for the adjusted model. *
p o .05. p o .001.
***
high prenatal depressive symptoms were 3.24 times (95% CI:1.76– 5.99) more likely to continue having borderline-high postnatal depressive symptoms compared to those who had low prenatal symptoms. In the adjusted model, we still found significant associations between sleep quality and postnatal depressive symptoms: women with poor subjective prenatal sleep were 1.85 times (95% CI:1.01–3.40) more likely to also have borderline-high postnatal depressive symptoms as compared to those who had good subjective sleep quality. 3.3. Subjective prenatal sleep and postnatal anxiety symptoms Logistic regression results in Table 2 revealed that in the unadjusted model, women with poor subjective prenatal sleep were 2.12 times (95% CI:1.21–3.70) more likely to have high postnatal anxiety symptoms as compared to those who had good subjective sleep. In addition, in the adjusted model, women with high anxiety symptoms during pregnancy were 6.18 times (95% CI:3.29–11.59) more likely to also have postnatal high anxiety symptoms as compared to those had low anxiety symptoms. In the adjusted model, there was no significant association between subjective prenatal sleep quality and postnatal anxiety symptoms.
4. Discussion Our findings show that poor subjective sleep quality during pregnancy was - independently from prenatal depressive symptoms - significantly associated with postnatal depressive Table 2. Logistic regression analyses between subjective prenatal sleep quality and postnatal anxiety symptoms. 95% CI for Odds Ratio Predictor
B (SE)
Lower
Odds Ratio
Unadjusted Model Prenatal PSQI Adjusted Model
.75** (.29) .047 (.17)
1.21 .67
2.12 .95
3.70 1.35
Education Prenatal STAI state Prenatal PSQI
1.82*** (.32) .28 (.32)
3.29 .71
6.18 1.32
11.59 2.46
Note: R2 ¼ .13 (Cox & Snell),.20 (Nagelkerke). ** ***
po .01. p o .001.
Upper
93
symptoms. In contrast, poor subjective prenatal sleep did not increase the odds of developing high postnatal anxiety symptoms after controlling for prenatal anxiety. Our findings are in concordance with the recent review of Lawson et al., 2015, who found an association between self-reported poor sleep and postnatal depression, but not anxiety. Although our findings showed that prenatal depression remained the strongest predictor of postnatal depression, these findings suggest that poor subjective prenatal sleep can be an extra risk factor for developing postnatal depression. It is possible that poor subjective sleep quality during pregnancy impacts coping after pregnancy, as women who perceive themselves as having poor sleep are also more likely to perceive themselves as having more postpartum stress (Bei et al., 2010; Roeser et al., 2012), thus in turn leading to increased symptoms of depression. Another criticism is that poor sleep is a common feature of depression (Skouteris et al., 2009), hence findings on postnatal depression may be driven solely by prenatal depression. However, in our study we found effects of poor subjective prenatal sleep while controlling for prenatal depression. Another possible pathway is that poor subjective prenatal sleep quality may relate to poor subjective postnatal sleep quality, which then leads to increased depressive symptoms. Even though poor subjective prenatal sleep is still involved in the above pathway, future studies should also investigate the potential role of postnatal sleep quality to gain more insights into the role of prenatal sleep on postnatal depression. The limited, but statistically significant, role of poor subjective prenatal sleep quality on the etiology of postnatal depressive symptoms suggest that, in addition to treatment of depression, treatment of sleep problems can be helpful (Haynes, 2015; Sutton, 2014). During pregnancy especially, non-pharmacological treatments could be considered such as sleep hygiene education, cognitive behavioral therapies and relaxation techniques (Haynes, 2015; Sutton, 2014). A strength of this study is that it replicates key findings from recent work focusing on depressive and anxiety symptoms among non-clinical samples (Bei et al., 2010; Skouteris et al., 2009; Swanson et al., 2011; Wu et al., 2014). Instead of excluding women with high symptoms (Wu et al., 2014), we used borderline cut-offs, as mild depressive and anxiety symptoms are more common in the general population. However, a limitation is the use of self-reported measurements, which may be subjective in nature. The association between sleep quality and perinatal mood has been reported to be stronger when subjective self-reported measures were used compared to objective measures (Bei et al., 2010). In addition, the study did not collect measures of sleep quality prior to pregnancy, hence we were not able to disentangle specific effects of sleep during pregnancy from participant's general sleep quality. Another limitation is that the women in our study were part of a larger study which may limit the generalizability of our findings due to selection bias. Although we used the same timepoints of measures during pregnancy (Bei et al., 2010; Wu et al., 2014) and postpartum (Wu et al., 2014) as other studies, the interpretation of our findings are only limited to these timepoints. Even though existing work has revealed that prevalence of maternal sleep problems is fairly stable from pregnancy up to 2 years postpartum (Sivertsen et al., 2015), it would be interesting for future studies to explore the relations between trajectories of sleep quality and depression/ anxiety during and after pregnancy to better predict causal pathways between peri-partum sleep and mood. In conclusion, poor subjective prenatal sleep quality increases the risk of postnatal depression but not anxiety, even after adjusting for the presence of prenatal symptoms. As prenatal depressive and anxiety symptoms were still the strongest predictors of postnatal depression and anxiety, treatment of depression and
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anxiety remain of utmost importance. Nonetheless, future studies may explore if treatments for sleep, such as sleep hygiene or relaxation techniques, may additionally help to reduce the risk for postnatal depression, in particular for women with antenatal borderline-high depressive symptoms.
Acknowledgements
(i) The GUSTO study group includes Pratibha Agarwal, Arijit Biswas, Choon Looi Bong, Birit F. P. Broekman, Shirong Cai, Jerry Kok Yen Chan, Yiong Huak Chan, Cornelia Yin Ing Chee, Helen Chen, Yin Bun Cheung, Audrey Chia, Amutha Chinnadurai, Chai Kiat Chng, Mary Foong-Fong Chong, Yap-Seng Chong, Shang Chee Chong, Mei Chien Chua, Eric Andrew Finkelstein, Doris Fok, Marielle V. Fortier, Peter D. Gluckman, Keith M. Godfrey, Anne Eng Neo Goh, Yam Thiam Daniel Goh, Joshua J. Gooley, Wee Meng Han, Mark Hanson, Christiani Jeyakumar Henry, Joanna D. Holbrook, Chin-Ying Hsu, Hazel Inskip, Jeevesh Kapur, Kenneth Kwek, Ivy Yee-Man Lau, Bee Wah Lee, Yung Seng Lee, Ngee Lek, Sok Bee Lim, Iliana Magiati, Lourdes Mary Daniel, Michael Meaney, Cheryl Ngo, Krishnamoorthy Niduvaje, Wei Wei Pang, Anqi Qiu, Boon Long Quah, Victor Samuel Rajadurai, Mary Rauff, Salome A. Rebello, Jenny L. Richmond, Anne Rifkin-Graboi, Seang-Mei Saw, Lynette Pei-Chi Shek, Allan Sheppard, Borys Shuter, Leher Singh, Shu-E Soh, Walter Stunkel, Lin Lin Su, Kok Hian Tan, Oon Hoe Teoh, Mya Thway Tint, Hugo P S van Bever, Rob M. van Dam, Inez Bik Yun Wong, P. C. Wong, Fabian Yap, George Seow Heong Yeo. (ii) This research is supported by the Singapore National Research Foundation under its Translational and Clinical Research (TCR) Flagship Programme and administered by the Singapore Ministry of Health's National Medical Research Council (NMRC), Singapore- NMRC/TCR/004-NUS/2008; NMRC/TCR/012-NUHS/ 2014. Additional funding is provided by the Singapore Institute for Clinical Sciences, Agency for Science Technology and Research (A*STAR), Singapore.
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