Montréal, Montreal, Quebec, Canada b IRSPUM Institut de recherche en santé publique de l'université de. Available online: 28 Jul 2011

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3 Women & Health, 51: , 2011 Copyright Taylor & Francis Group, LLC ISSN: print/ online DOI: / Child Asthma and Change in Elevated Depressive Symptoms Among Mothers of Children of a Birth Cohort from Quebec MAI THANH TU, PhD Department of Social & Preventive Medicine, Université de Montréal, Montreal, Quebec, Canada, and IRSPUM Institut de recherche en santé publique de l université de Montréal and CRCHUM Centre de Recherche du Centre Hospitalier de l Université de Montréal, Montreal, Quebec, Canada GENEVIÈVE PERREAULT, MD, MSc Department of Social & Preventive Medicine, Université de Montréal, Montreal, Quebec, Canada LOUISE SÉGUIN, MD, MPH Department of Social & Preventive Medicine, Université de Montréal, Montreal, Quebec, Canada, and IRSPUM Institut de recherche en santé publique de l université de Montréal and Léa-Roback Research Centre on Social Inequalities in Health in Montreal, Université de Montréal, Montreal, Quebec, Canada LISE GAUVIN, PhD Department of Social & Preventive Medicine, Université de Montréal, Montreal, Quebec, Canada, and CRCHUM Centre de Recherche du Centre Hospitalier de l Université de Montréal, Montreal, Quebec, Canada The authors examined the association between maternal reports of child asthma attacks since birth and occurrence of elevated maternal depressive symptoms at seventeen months postpartum in the present study. The modifying role of poverty in this association Received December 13, 2010; revised May 18, 2011; accepted May 20, The IRSPUM and CRCHUM receive infrastructure funding from the Fonds de la Recherche en Santé du Québec. MTT is funded by a postdoctoral CIHR fellowship (CIHR #181755). MTT was also awarded the Young Investigator Award from the NARSAD, the Brain and Behavior Research Foundation. LG holds a CIHR/CRPO (Centre de recherche en prévention de l obésité) Applied Public Health Chair on Neighbourhoods, Lifestyle, and Healthy Body Weight. The Direction Santé Québec of the Institut de la Statistique du Québec was in charge of data collection. The authors would like to thank Béatrice Nikiéma for their helpful assistance. Address correspondence to Louise Séguin, MD, MPH, Department of Social and Preventive Medicine, Université de Montréal, P. O. Box 6128, Downtown Station, Montréal, Québec, Canada H3C 3J7. louise.seguin@umontreal.ca 461

4 462 M. T. Tu et al. was also examined. Data from n D 1,696 mother child dyads from the Quebec Longitudinal Study of Child Development, a birth cohort of children born in 1998, were used. Maternal depressive symptoms were measured with an abridged and validated twelveitem version of the Center for Epidemiologic Studies Depression Scale. Maternal reports of child asthma attacks since birth in relation to the occurrence of maternal depressive symptoms at 17 months postpartum and the potential modifying role of poverty were tested using multiple logistic regression models. When mothers reported child asthma attacks, those without elevated depressive symptoms at 5 months postpartum had lower odds of elevated depressive symptoms one year later (OR D 0.2, 95% CI: ). Poverty was associated with increased odds of elevated maternal depressive symptoms (OR D 2.4, 95% CI: ), without interacting with child asthma. Through this study, the authors suggest that in mothers without elevated symptoms at 5 months, reported child asthma attacks since birth did not contribute one year later to new occurrence of depressive symptoms. KEYWORDS child asthma, maternal depressive symptoms, poverty, longitudinal studies INTRODUCTION Maternal depressive symptoms are frequent, with the prevalence varying between 6.5% and 25% during the postpartum period (McLennan, Kotelchuck, & Cho, 2001; McLearn et al., 2006). Although postpartum depression has been the focus of much research, few data are available regarding maternal depressive symptoms after the child s first year of life. Higher levels of maternal depressive symptoms are indicative of maternal depression (Radloff, 1977) which may have negative consequences, such as suffering of the mother, deterioration of the mother child relationship, child emotional and cognitive problems, less frequent preventive practices, marital difficulties, and family functioning problems when it becomes chronic (Jameson et al., 1997; Johnson & Jacob, 1997; Cichetti, Rogosch, & Toth, 1998; McLennan & Kotelchuck, 2000; Burke, 2003; Dawson et al., 2003). The major focus of research and clinical studies on maternal depressive symptoms during the year following childbirth rather than beyond may be due to several reasons, including greater prevalence for elevated depressive symptoms during the year following child birth and more vulnerability in the child s behavior and socioemotional development when exposed to severe and prolonged symptoms during that critical time frame. However, it is important to note that depressive symptoms in women may not be restricted to the postpartum

5 Child Asthma and Change in Maternal Depressive Symptoms 463 period as they may occur at any time during a woman s life course, with negative consequences on children s development (Ashman, Dawson, & Panagiotides, 2008). Risk factors for maternal depressive symptoms remain to be defined more clearly in the literature. Of particular interest is the role that caring for a child with chronic health problems may play. Indeed, some studies show an association between child chronic illnesses, handicaps, or retarded growth and presence of maternal psychological distress (Gudmundsdóttir, Elklit, & Gudmundsdóttir, 2006; Patiño Fernández et al., 2008) or maternal depressive symptoms (Silver, Bauman, & Weiss, 1999; O Brien et al., 2004; Kashikar Zuck, 2008), while others did not find any association (Gowen et al., 1989; Manuel et al., 2003). Studies indicate that the severity of maternal depressive symptoms is associated with the extent of functional limitations and the degree of dependence of the child on the mother but not necessarily with the nature of the handicap (Breslau, Staruch, & Mortimer, 1982; Silver, Bauman, & Weiss, 1999; Yilmaz et al., 2010). On the other hand, stress and depression or depressive symptoms during pregnancy may also make the child more vulnerable to childhood illnesses (for a review, see Brand & Brennan, 2009). Childhood asthma is a chronic illness that may affect up to 10% of children, with the prevalence increasing in past decades worldwide (Casey et al., 2002). Given the anxiety that child asthma can generate in mothers and the burden due to difficult asthma management in young children, it is possible that child asthma may contribute to elevated maternal depressive symptoms (Akcakaya et al., 2003; Gustafsson, Kjellman, & Bjorksten, 2002; Kub et al., 2009; Shalowitz et al., 2006; Leao et al., 2009). Yet, few studies have examined the association between child asthma and maternal depressive symptoms (Akcakaya et al., 2003) and even the direction remains elusive (Gustafsson, Kjellman, & Bjorksten, 2002). Studies have either shown a positive association (Kub et al., 2009), or did not find any significant association in a sample of low income mothers (Shalowitz et al., 2006). Other research focused more extensively on the impact of child asthma on parents quality of life (Levy et al., 2004; Williams et al., 2000; Ozkaya et al., 2010; Wright, 2011) or on the impact of maternal depression on child asthma morbidity and use of health care services (Bartlett et al., 2001; Klinnert et al., 2001). Defining and diagnosing child asthma is particularly difficult during the first years of life as asthma-like symptoms are unstable and can be due to other ailments (Klinnert et al., 2001; Kurukulaaratchy, Matthews, & Arshad, 2004). Finally, poverty represents an important risk factor for maternal depression (McLennan, Kotelchuck, & Cho, 2001; Beeghly et al., 2003; Casey et al., 2004; Heneghan, 1998; Horowitz & Goodman, 2004; Mulvaney & Kendrick, 2005; Seto et al., 2005) as well as for child health problems, including asthma (Phipps, 2003; Ross & Roberts, 1999; Seguin et al., 2005; Spencer, 2000; Wood, 2003). Thus, it is possible that poverty may play a modifying role in

6 464 M. T. Tu et al. the association between maternal depressive symptoms and child asthma. However, the literature has mostly examined families with low household income (Bartlett et al., 2001, 2004; Shalowitz et al., 2006; Kub et al., 2009) thus limiting the ability to address this issue. To the knowledge of the authors, only one study on exposure to maternal distress from birth to 7 years of age in a population-based low-risk cohort has reported possible differences in child asthma between low-income and high-income families but did not examine the impact of child asthma on the mother (Kozyrskyj et al., 2008). To the knowledge of the authors, no study has examined poverty as a potential modifying factor of the association between childhood asthma and occurrence of maternal depressive symptoms. Given these gaps in the literature, the main objective of the authors in this study was to assess the association between maternal reports of childhood asthma attacks since birth and occurrence of elevated maternal depressive symptoms at 17 months postpartum in a population-based study, while controlling for maternal and child characteristics and psychosocial environment. A secondary aim was to examine the modifying role of poverty on this association. METHODOLOGY Study Participants The analyses were carried out using data from the first two rounds of the Quebec Longitudinal Study of Child Development (QLSCD) from the Institut de la Statistique du Québec (Jetté, 2002). The QLSCD is a birth cohort in which children were followed annually since the age of five months. The initial objective of the researchers in this cohort study was to examine factors associated with childhood development and school readiness. The current secondary data analysis was based on longitudinal data collected when children in the cohort were five and 17 months old on average. The participants in the cohort were selected randomly from the Québec live births registry to be representative of singleton births in Quebec in , with the exception of births in Northern Québec, in Cri and Inuit territories, and on First Nations reservations (2.1%). Babies of unknown gestational age and those born before 24 or after 42 gestational weeks (1.4%) were also excluded (Jetté, 2002). About 1.3% of births had missing data on the birth registry, leading to exclusion from the recruitment process. Participants were not over-sampled to account for these exclusions. Recruitment was from households distributed geographically according to regional densities in the province of Quebec. Selected households received by postal mail a letter and a flyer introducing the main agencies in charge of the study, its purpose, and importance for public health. Families were invited to call the office

7 Child Asthma and Change in Maternal Depressive Symptoms 465 responsible for data collection to enroll. The households recruited to join the QLSCD cohort were representative of 94.4% of the Quebec population. The response rate at recruitment in 1998 was 83.1%, resulting in 2,120 families participating in the longitudinal study. In 1999, when the child was 17 months old, 2,045 families participated with a participation rate of 96.4% (Jetté, 2002). The principal causes for attrition were: unable to retrace families (0.4%), families excluded because they had moved too far (0.5%), and refusal to participate (2.6% in 1999). Data Collection The study was approved by the Human Research Ethics Committee of the Faculty of Medicine of Université de Montréal. Three sources of data were used: hospital birth records, home interviews, and questionnaires selfadministered by the mother. Interviews were performed at home with the child s main caregiver, after obtaining their written informed consent. The questions dealt with mother and child s health and the psychosocial environment. As the study concerned maternal depressive symptoms, respondents other than the biological mother were excluded from the study, leaving 1,962 mother child dyads. The dependent variable depressive symptoms was assessed with the abridged 12-item version of the Center for Epidemiologic Studies Depression Scale (CES-D; Radloff, 1977), which has been used in the National Longitudinal Study of Children and Youth (NLSCY, 1995) and has been shown to have good construct validity (Poulin, Hand, & Boudreau, 2005a; Poulin et al., 2005b). The abridged version was derived from the CES-D, a 20-item selfreport measurement instrument shown to be reliable and valid in different studies (Hann, Winter, & Jacobsen, 1999; Himmelfarb & Murrell, 1983; Radloff & Locke, 1986). Respondents quantified the frequency of different depressive symptoms experienced over the previous week. In the present study, the authors used an abridged 12-item version The 12-item version provides scores ranging from 0 to 36, with a score 12 indicative of the presence of elevated depressive symptoms (Poulin, Hand, & Boudreau, 2005a). The internal consistency of the scale is high (Cronbach s alpha D 0.85) (Poulin, Hand, & Boudreau, 2005a). Dichotomous outcomes (score < 12 vs. score 12) were created for measures recorded at each time point (5 months and 17 months postpartum). The presence of at least one asthma attack in the child since birth, as reported by the mother when the child was 17 months old was the principal independent variable in the study. Poverty was categorized as having an insufficient income, such as below the low-income cut-off (LICO) as defined by Statistics Canada. These LICOs were adjusted according to the number of family members and the urban or rural area of residence. For instance, in 2000, the LICO before tax was $18,371 Canadian dollars (CAD) for a single

8 466 M. T. Tu et al. adult, or $34,572 CAD for a family of four people, living in an urban community with more than 500,000 residents, such as metropolitan areas of Montreal, Vancouver, or Toronto. In smaller communities (between 100,000 and 499,999 residents), the LICO before tax in 2000 was $15,757 CAD for a single adult or $29,653 for a family of four people (Income Statistics Division, 2009). Several control variables were included in the analyses: maternal characteristics (age, immigrant status, level of education, job status, and marital situation), maternal health (chronic physical illness, smoking, problems with drug use, unwanted pregnancy), characteristics of the child (sex, birth weight, breastfed, sleeping pattern, child-care method, temperament), and psychosocial environment (social support and family functioning). Two variables were created for social support: (1) presence of instrumental support (overall support, for baby care, household chores, and during times of work overload); and (2) presence of emotional support measured using an abridged validated version of the Social Provision Scale used in the National Longitudinal Study of Children and Youth (NLSCY; Jetté, 2000). The selected questions assessed the extent of the mother s access to support from people in whom she can confide, who make her feel secure and happy, and who can provide her with material aid when needed (Caron, 1996). Scores on these scales were categorized using tertile cut-offs: high, moderate, and low levels of support. Measures of family functioning were collected with a scale also used in the NLSCY to assess intra-household quality of relationships in problem solving, communication, parenting roles, emotional receptivity, emotional participation, and behavioral control (Thibault et al., 2003). Statistical Analyses The analyses were performed in four steps: descriptive analyses, bivariate analyses, analysis of multivariate logistic regression models, and analysis of interactions. Because the dependent variable of interest was the occurrence of elevated depressive symptoms at 17 months postpartum, all analyses were performed using presence of elevated depressive symptoms at 17 months postpartum as the outcome variable while controlling for presence of elevated depressive symptoms at 5 months postpartum. After descriptive analyses, bivariate analyses were conducted to examine associations between presence of asthma attack, confounding variables, and occurrence of elevated maternal depressive symptoms. For confounding variables, variables shown in the literature to be associated with maternal depressive symptoms, as well as those presenting an association reaching p 0.25 in bivariate analyses, were retained for subsequent analysis. Following bivariate analyses, correlation analyses allowed for the identification of strongly correlated variables. When a moderate (r 0.35) and significant (p < 0.05) correlation was observed, the variable most strongly associated with the dependent variable was used for subsequent analyses.

9 Child Asthma and Change in Maternal Depressive Symptoms 467 Then, multivariate logistic regression analyses were conducted. After including presence of elevated depressive symptoms at 5 months, variables were added in blocks: (1) presence of child asthma attack, (2) sociodemographic variables, (3) maternal health, (4) child characteristics, and (5) psychosocial environment. The Hosmer-Lemeshow goodness-of-fit test was used to verify model fit. Finally, the modifying effect of poverty in any associations between presence of child asthma attacks since birth and occurrence of elevated maternal depressive symptoms was examined by adding interaction terms. This final model with interaction terms only included significant confounding variables if the direction and significance were similar to the analyses performed with all variables used in the multivariable analyses. Statistical analyses were carried out with SPSS 12.0 for Windows software. RESULTS Analyses were conducted on 1,696 mother child dyads who participated at both 5 months and 17 months postpartum. At 5 months postpartum, 12.2% of mothers presented elevated depressive symptoms. When the children were 17 months old, this proportion was only 8.6%. At that age, 16.9% of families were poor, and 6.8% of the mothers reported at least one childhood asthma attack since birth. Mothers included and excluded from the analysis based on missing data at either 5 months or 17 months postpartum did not differ in their reports of whether or not any asthma attack had occurred in their child since birth. They were also comparable for their immigrant status, maternal physical health problems, problems with drug use, sex of the child, birth weight, breastfeeding, child care method, child temperament at 5 months, child sleep pattern, emotional support, and family functioning. However, those excluded due to missing data presented a greater proportion of elevated depressive symptoms at 17 months and differed on many confounding variables (Table 1), such as being either younger than 20 years old or over 35 years old at childbirth. They were also more likely to be unemployed, without a completed high school education, were heading a single parent household, were a smoker, had a child with birth weight below 2,500 g, had not desired the pregnancy, and had poorer instrumental support. In further analyses, the only variables not associated with maternal depressive symptoms at 17 months, in analyses adjusted for such symptoms at 5 months postpartum, were age of the mother, maternal physical health problems, and duration of pregnancy (Table 2). However, as the latter variables were associated with at least one of the independent variables, they were included in the multivariable models. Although the unadjusted odds ratio between maternal report of childhood asthma attack since birth and occurrence of elevated maternal depressive symptoms at 17 months

10 468 M. T. Tu et al. TABLE 1 Characteristics 1 of the Mother Child Dyads from the QLSCD that Were Included and Excluded from Analyses Mother child dyads included (total n D 1,696) %(n) Mother child dyads excluded (n D 266) %(n) Elevated depressive symptoms at 5 months postnatal No 87.8 (1,489) 88.4 (236) Yes 12.2 (207) 11.6 (30) Elevated depressive symptoms at 17 months postnatal*** No 91.4 (1,550) 84.1 (224) Yes 8.6 (146) 15.9 (42) Asthma attack since birth No 93.2 (1,580) 91.3 (243) Yes 6.8 (116) 8.7 (23) Income*** Not below poverty line 83.1 (1,409) 59.7 (168) Below poverty line 16.9 (287) 40.3 (98) Age of the mother at birth** < 20 years 2.3 (39) 5.6 (15) years 85.0 (1,441) 78.6 (209) 35 years 12.7 (216) 15.8 (42) Immigrant status Not or European origin 92.5 (1,569) 91.7 (244) Non-European origin 7.5 (127) 8.3 (22) Employment* Unemployed 29.1 (494) 37.4 (99) Part-time 20.6 (350) 19.6 (52) Full-time 50.2 (852) 43.0 (114) Education*** < High school 15.5 (263) 27.8 (74) High school 25.6 (435) 28.2 (75) College 30.6 (519) 23.7 (63) University 28.2 (479) 20.3 (54) Living with a partner*** Yes 96.1 (1,630) 59.8 (159) No 3.9 (66) 40.2 (107) Maternal physical health problem No 60.4 (1,025) 57.4 (153) Yes 39.6 (671) 42.6 (113) Smoking** Less than daily 75.6 (1,283) 67.4 (181) Daily 24.4 (413) 32.6 (85) Desired the pregnancy*** Yes 84.3 (1,436) 74.8 (213) No 15.3 (260) 25.2 (53) Problem with drug use No 95.9 (1,626) 94.4 (251) Yes 4.1 (70) 5.6 (15) (continued)

11 Child Asthma and Change in Maternal Depressive Symptoms 469 TABLE 1 Characteristics 1 of the Mother Child Dyads from the QLSCD that Were Included and Excluded from Analyses (Continued) Mother child dyads included (total n D 1,696) %(n) Mother child dyads excluded (n D 266) %(n) Sex of the child Female 50.2 (851) 47.4 (126) Male 49.8 (845) 52.6 (140) Birth weight of the baby** 2500 g 97.1 (1,646) 93.2 (249) < 2500 g 2.9 (50) 6.8 (17) Breast-feeding? Never 29.2 (495) 34.2 (91) Stopped 67.1 (1,138) 60.2 (160) Still breast-feeding 3.7 (63) 5.6 (15) Child-care method At home 50.8 (861) 56.0 (149) Outside the home 39.2 (665) 34.6 (92) Day care 10.0 (170) 9.4 (25) Child s temperament at 5 months Easy-going 44.5 (775) 39.8 (70) Average 38.9 (660) 49.2 (69) Difficult 16.6 (281) 21.0 (37) Child s sleep pattern? Sleeping thru night 88.5 (1,501) 87.2 (232) Not sleeping thru night 11.5 (195) 12.8 (34) Emotional support Good 61.2 (1,038) 58.3 (155) Moderate 23.7 (402) 24.2 (64) Poor 15.1 (256) 17.4 (46) Instrumental support*** Good 52.3 (886) 34.1 (78) Moderate 21.6 (367) 14.4 (33) Poor 26.1 (443) 51.8 (118) Family functioning Good 29.7 (503) 25.6 (45) Moderate 53.8 (912) 53.4 (94) Poor 16.6 (281) 21.0 (37) Notes. Source: Institut de la statistique du Québec. 1 Characteristics at 17 months unless specified otherwise.? p < 0.10, *p < 0.05, **p < 0.01, ***p < postpartum was not statistically significant in multivariable models (OR D 0.6; 95% CI: , Table 2), adding maternal and child characteristics as well as those related to psychosocial environment revealed a statistically significant negative (protective) relationship between maternal report of childhood asthma attack since birth and the occurrence of elevated maternal depressive symptoms at 17 months (OR D 0.4; 95% CI: ) (Table 3). Poverty was also significantly associated with elevated depressive symptoms at 17 months postpartum (OR D 2.4, 95% CI: ). Other factors as-

12 470 M. T. Tu et al. TABLE 2 Unadjusted Associations (Odds Ratios and 95% Confidence Intervals) Between Child Asthma Attacks Since Birth, Confounding Variables and Elevated Maternal Depressive Symptoms at 17 Months Controlling for Elevated Maternal Depressive Symptoms at 5 Months Postpartum (n D 1,696) (QLSCD) OR (95% CI) Asthma attack since birth Absence (Referent) 1.0 Presence 0.6 ( )? Income Above low-income cut-off (Referent) 1.0 Below low-income cut-off 3.4 ( )* Age of the mother at birth < 20 years 1.2 ( ) 20 to 34 years (Referent) years 0.9 ( ) Immigrant status Non immigrant or of European origin (Referent) 1.0 Non-European origin 2.1 ( )* Employment Full-time (Referent) 1.0 Unemployed 1.6 ( )* Part-time 0.9 ( ) Education < High school 2.3 ( )* High school 2.0 ( )* College 1.7 ( )* University (Referent) 1.0 Living with a partner Presence (Referent) 1.0 Absence 3.4 ( )* Maternal physical health problem Absence (Referent) 1.0 Presence 1.2 ( ) Maternal tobacco use No or occasional (Referent) 1.0 Daily 1.4 ( )? Desired the pregnancy Yes (Referent) 1.0 No 1.6 ( )** Problem with drug use Absence (Referent) 1.0 Presence 3.4 ( )* Sex of the child Female (Referent) 1.0 Male 0.8 ( )? Birth weight of the baby 2500 g (Referent) 1.0 < 2500 g 0.4 ( )? Breast-feeding Still breast-feeding (Referent) 1.0 Never 1.9 ( )? Stopped 1.3 ( ) (continued)

13 Child Asthma and Change in Maternal Depressive Symptoms 471 TABLE 2 Unadjusted Associations (Odds Ratios and 95% Confidence Intervals) Between Child Asthma Attacks Since Birth, Confounding Variables and Elevated Maternal Depressive Symptoms at 17 Months Controlling for Elevated Maternal Depressive Symptoms at 5 Months Postpartum (n D 1,696) (QLSCD) (Continued) OR (95% CI) Child-care method At home (Referent) 1.0 Outside the home 0.6 ( )* Day care 0.8 ( ) Child s temperament at 5 months Easy-going (Ref) 1.0 Average 2.4 ( )* Difficult 6.7 ( )* Child s sleep pattern Sleeping thru the night (Referent) 1.0 Not sleeping thru the night 1.6 ( )? Emotional support Good (Referent) 1.0 Moderate 2.5 ( )* Poor 4.1 ( )* Instrumental support Good (Referent) 1.0 Moderate 1.5 ( )* Poor 2.0 ( )? Family functioning Good (Referent) 1.0 Moderate 3.1 ( )* Poor 9.3 ( )* Notes. Source: Institut de la statistique du Québec.? p < 0.10, *p < 0.05, **p < 0.01, ***p < sociated with the occurrence of elevated maternal depressive symptoms at 17 months postpartum included maternal drug use, a difficult temperament in the child, poor or moderate emotional support, and poor family functioning. To understand the protective relationship between maternal report of childhood asthma attack since birth and the occurrence of elevated maternal depressive symptoms, additional analyses were performed. The negative association between presence of childhood asthma attack and the mother s depressive symptoms at 17 months postpartum was statistically significant across levels of income and of social support and was not modified by poverty. More interestingly, in a model adjusted for all variables shown to be significant confounding factors (i.e., maternal drug use, a difficult temperament in the child, poor or moderate emotional support, and poor family functioning), a statistically significant interaction was observed between the presence of depressive symptoms in the mother when the child was age 5 months and subsequent negative association between presence

14 472 M. T. Tu et al. TABLE 3 Final Multivariate Models Testing the Association Between Presence of Asthma Attack Since Birth and Occurrence of Elevated Maternal Depressive Symptoms at 17 Months Postpartum (Adjusted Odds Ratios and 95% Confidence Intervals) While Adjusting for Potential Confounding Variables (QLSCD) Model OR (95% CI) Presence of child asthma attacks No (Referent) 1.00 Yes 0.4 ( )* Elevated depressive symptoms at 5 months No (Referent) 1.00 Yes 0.7 ( ) Insufficient income No (Referent) 1.00 Yes 2.4 ( )*** Mother s age at birth < 20 years 0.7 ( ) 20 to 35 years (Referent) years 0.7 ( ) Employment Full-time (Referent) 1.00 Unemployed 0.8 ( ) Part-time 0.9 ( ) Immigrant Non-Immigrant or European Origin (Referent) 1.00 Non-European origin 1.1 ( ) Education < high school 1.0 ( ) High school 1.2 ( ) Post-secondary 1.3 ( ) University (Referent) 1.00 Living with a partner Yes (Referent) 1.00 No 1.6 ( ) Maternal physical health problem No (Referent) 1.00 Yes 1.2 ( ) Desired the pregnancy Yes (Referent) 1.00 No 1.0 ( ) Smoking No or Occasional (Referent) 1.00 Daily 1.1 ( ) Drug use No (Referent) 1.00 Yes 2.5 ( )** Sex Female (Referent) 1.00 Male 0.8 ( ) (continued)

15 Child Asthma and Change in Maternal Depressive Symptoms 473 TABLE 3 Final Multivariate Models Testing the Association Between Presence of Asthma Attack Since Birth and Occurrence of Elevated Maternal Depressive Symptoms at 17 Months Postpartum (Adjusted Odds Ratios and 95% Confidence Intervals) While Adjusting for Potential Confounding Variables (QLSCD) (Continued) Model OR (95% CI) Birth weight 2500 g (Referent) 1.00 < 2500 g 0.2 ( ) Breast-feeding Still breast-feeding (Referent) 1.00 Never 2.2 ( ) Stopped 1.5 ( ) Child-care method At home (Referent) 1.00 Outside the home 0.7 ( ) Day care 0.9 ( ) Child s sleep pattern Sleeping thru the night (Referent) 1.00 Not sleeping thru the night 1.2 ( ) Child s temperament at 5 months Easy going (Referent) 1.00 Moderate 1.3 ( ) Difficult 5.0 ( )*** Emotional support Good (Referent) 1.00 Moderate 1.8 ( )*** Poor 2.2 ( )** Instrumental support Good (Referent) 1.00 Moderate 1.4 ( ) Poor 1.3 ( ) Family functioning Good (Referent) 1.00 Moderate 2.1 ( ) Poor 5.0 ( )*** Notes. Source: Institut de la statistique du Québec. *p < 0.05, **p < 0.01, ***p < of childhood asthma attack and the mother s depressive symptoms at 17 months (Table 4). In other words, the protective association of childhood asthma attacks with elevated maternal depressive symptoms at 17 months postpartum was present only among women who did not show elevated depressive symptoms at 5 months postpartum. Among mothers who had elevated depressive symptoms at that earlier time, reported childhood asthma attack since birth had a non-significant increased odds of elevated depressive symptoms at 17 months with wide confidence intervals (adjusted OR D 1.9, 95% CI: ). However, the odds of elevated depressive symptoms at 17 months was significantly reduced in the presence of childhood asthma

16 474 M. T. Tu et al. TABLE 4 Interaction Between the Presence of Childhood Asthma Attack Since Birth and the Presence of Elevated Maternal Depressive Symptoms at 5 Months on the Probability of Elevated Depressive Symptoms at 17 Months (Adjusted OR and 95% Confidence Intervals), Adjusted for Confounding Variables* (QLSCD) Absence of elevated depressive symptoms at 5 months OR (95% CI) Presence of elevated depressive symptoms at 5 months OR (95% CI) Absence of asthma attack since birth 1.0 (Referent) 0.6 ( ) Presence of asthma attack since birth 0.2 ( )** 1.9 ( ) Notes. Source: Institut de la statistique du Québec. *Household income, drug use, child temperament at 5 months, emotional support, instrumental support, and family functioning. **p < attack among mothers who had not had depressive symptoms at 5 months postpartum (adjusted OR D 0.2, 95% CI: ). DISCUSSION In this study the authors examined the association between presence of child asthma attack since birth as reported by the mother and occurrence of elevated maternal depressive symptoms at 17 months postpartum while controlling for previous elevated maternal depressive symptoms, for poverty and other factors related to the mother, child, and psychosocial environment. Interestingly, by revealing a negative protective association between maternal reports of childhood asthma attacks since birth and occurrence of elevated depressive symptoms at 17 months among mothers without prior elevated depressive symptoms, the findings reported here contrast with conclusions from previous studies. Furthermore, this study showed that among mothers with elevated depressive symptoms at 5 months, maternal reports of childhood asthma attacks were not statistically significantly associated with elevated depressive symptoms at 17 months postpartum, although a nonsignificant tendency toward increased odds of elevated depressive symptoms was observed with wide confidence intervals. Some studies have shown a greater prevalence of depressive symptoms among parents of asthmatic children (Kub et al., 2009) and among those who visit an emergency room for child asthma attacks (Bartlett et al., 2001). In contrast, other studies have shown the absence of an association between child asthma and maternal depressive symptoms, although the severity of the child s asthma seems to be associated with maternal depressive symptoms (Klinnert et al., 2001; Shalowitz et al., 2006). The current findings may partially explain the absence of a consensus in the literature regarding the association between presence of child asthma and elevated maternal

17 Child Asthma and Change in Maternal Depressive Symptoms 475 depressive symptoms, which may vary as a function of presence or absence of prior elevated maternal depressive symptoms. Nevertheless, the results should be treated with caution. Because this current study was based on secondary analyses from a longitudinal study, the information gathered were from a newly developed abridged questionnaire with items taken from validated questionnaires, rather than using the full-length validated questionnaires for each aspect studied in this cohort. Mothers report of childhood asthma attack was only an estimate of the child s respiratory condition. However, such maternal report was indicative of respiratory distress experienced by the child that may be asthma, although asthma is not stable at that young age and difficult to diagnose with certainty. Details regarding child respiratory problems severity were not available in this study. It is possible that compared to children whose mothers had elevated depressive symptoms at 5 months of age, children whose mothers did not have such an elevation in depressive symptoms at that time had less severe asthma. Furthermore, the items from the CES-D used in this study assess depressive symptoms within the past week only. This may be a limitation to this study as it only provides a snapshot view of depressive states, rather than an overall account of more prolonged exposure to depressive symptoms. Caring for a child with a chronic illness may be stressful for many parents. Yet, positive perceptions such as personal growth, family strength, and closeness can still develop (Hastings & Taunt, 2002; Greer, Grey, & McClean, 2006), including in families caring for an asthmatic child. Studies documented factors related to resilience to depression within families with asthmatic children as being resistant to the burden of child asthma management thanks to an increased feeling of family cohesion, fewer family conflicts, less anxiety in the partner, better social support, development of routines for treating the illness, or higher level of communication (Donnelly, 1994; Fiese, Wamboldt, & Anbar, 2005; Markson & Fiese, 2000; Svavarsdottir, Rayens, & McCubbin, 2005; Svavarsdottir, McCubbin, & Kane, 2000). Through the recommended strategies for caring for an asthmatic child, parents are impelled to take an active role in asthma management by being more vigilant for asthma symptoms, providing a greater sense of control over the problem, which in turn, might alleviate their distress level. Furthermore, this enhanced scrutiny while caring for an asthmatic child could translate into a family ritual, which may contribute to family resiliency (Markson & Fiese, 2000). The absence of depressive symptoms in mothers at 5 months may encourage optimal asthma management, adaptation, and development of resiliency factors, which in turn protect the mother against subsequent elevated depressive symptoms. Thus, these studies suggest that the relationship between child asthma and maternal depressive symptoms is a complex phenomenon. Although the study design controls for a high number of confounding factors, it is difficult to take all the potential factors into account.

18 476 M. T. Tu et al. A secondary aim of the authors in the present study was to examine the modifying role of poverty in the association between maternal reports of child asthma attack and the occurrence of elevated depressive symptoms. The finding that insufficient income increased the odds of developing elevated depressive symptoms is consistent with several other studies (McLennan, Kotelchuck, & Cho, 2001; Beeghly et al., 2003; Casey et al., 2004; Heneghan et al., 1998; Mulvaney & Kendrick, 2005; Seto et al., 2005). However, the study detected no interaction effect between poverty and report of asthma in the child with regard to occurrence of maternal depressive symptoms at 17 months postpartum. In addition to poverty, problems associated with drug use, a sub-optimal level of family functioning, a difficult temperament in the child, and a poor level of emotional support were associated with the presence of elevated depressive symptoms at this time. These results are in keeping with previous reports (Burke, 2003; Cichetti, Rogosch, & Toth, 1998; Beeghly et al., 2003; Beck, 1996, 2001; Grant, 1995; Sugawara et al., 1999). In addition to the methodological limitations mentioned previously, the attrition associated with cohort follow-ups represents a limitation for longitudinal studies. Attrition was low yet was more likely to occur among women with greater depressive symptoms. As a higher proportion of mothers with greater depressive symptoms were in the group excluded from the analyses because of missing data, the findings reported in this study may have underestimated the association between maternal report of child asthma attacks since birth and occurrence of elevated maternal depressive symptoms at 17 months postpartum. This was also true for poverty, hence heightening the difficulty to observe a possible interaction effects with child asthma. Moreover, the data in this study were self-reported, which could cause the participants to over- or under-declare certain variables. In addition, mothers with greater depressive symptoms may have had greater memory bias, which could have contributed to under-estimation of the relationship between reports of child asthma attack and maternal depressive symptoms. Finally, overadjustment was possible given the large number of variables in the equation. Despite its methodological limitations, this study had many strong points. This was a population-based survey, using a large number of mother child dyads, derived from a birth cohort representative of singleton births in Quebec in with a high participation rate. This contrasts with previous studies that relied on smaller samples from specialized medical clinics and were thus limited to subgroups of vulnerable women. The use of items from validated instruments to measure the variables was another strength of this study. In addition, the study design was longitudinal, which allowed for controlling for the presence of previous depressive symptoms in the mother. Finally, this study controlled for a large number of variables, such as social support, thus limiting the possibility that external factors could explain the results observed.

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