Journal of Affective Disorders 175 (2015) 454–462

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Older maternal age and major depressive episodes in the first two years after birth: Findings from the Parental Age and Transition to Parenthood Australia (PATPA) study Catherine A. McMahon a,n, Jacky Boivin b, Frances L. Gibson c, Karin Hammarberg d, Karen Wynter d, Jane R.W. Fisher d a

Centre for Emotional Health, Department of Psychology, Macquarie University North Ryde, NSW, 2109, Australia Cardiff Fertility Studies Research Group, School of Psychology, Cardiff University, UK Institute of Early Childhood Macquarie University, Australia d Jean Hailes Research Unit, School of Public Health & Preventive Medicine, Monash University, Australia b c

art ic l e i nf o

a b s t r a c t

Article history: Received 11 June 2014 Received in revised form 10 December 2014 Accepted 14 January 2015 Available online 30 January 2015

Background: This study examines whether (1) older maternal age is associated with increased risk of depressive episodes between four months and two years after first birth and (2) the role of subsequent reproductive, social and child factors in vulnerability to later onset depression. Method: 592 women were recruited in the third trimester of pregnancy in three age-groups ( r 30 years; 31–36 years, Z37 years); 434 (73%) completed all assessments at four months and two years after birth. Major Depression episodes (MDE) were assessed at four months and two years using the Mini International Neuropsychiatric Interview (MINI). Maternal (age, mode of conception, prior mood symptoms, health), child (temperament, health), reproductive (subsequent fertility treatment, pregnancy, birth, pregnancy loss) and social contextual variables (language background, paid work, practical support, life stresses) were assessed in pregnancy and postnatally using validated questionnaires and structured interview questions. Results: Maternal age was not related to prevalence or timing of MDE. Depression symptoms, poor child health, low practical support at four months and a non-English language background predicted episodes of depression between four months and two years, ps o0.05. Limitations: Life history risks for depression were not considered, nor symptom profiles over time. Conclusions: Findings indicate that despite a more complex reproductive context, older first time mothers are not more likely to report major depressive episodes in the first two years after birth. Prevalence for the whole sample was at the lower end of reported community ranges and was comparable early and later in the postpartum period. Screening for depression after childbirth should not be restricted to the early months. & 2015 Elsevier B.V. All rights reserved.

Keywords: Maternal age Postnatal depression ART conception

1. Introduction The trend to older maternal age at first birth is now well established (Schmidt et al., 2012; Human Fertilisation and Embryology Authority, 2013a), but there is scant empirical evidence regarding psychological wellbeing of older first time mothers during early parenthood. Anecdotal comment and media commentary has contributed to some representations of older mothers as anxious and difficult (Shaw and Giles, 2009), and there has been speculation that age-related physical health deficits and limited physical stamina might compromise parenting adaptation (Bornstein et al., 2006).

n

Corresponding author. Tel.: þ 61 2 9850 6213. E-mail address: [email protected] (C.A. McMahon).

http://dx.doi.org/10.1016/j.jad.2015.01.025 0165-0327/& 2015 Elsevier B.V. All rights reserved.

While age-related biological risks are well documented, these may be offset by more positive family and social circumstances, and personal competencies associated with older age that may act as protective factors during the transition to parenthood. Empirical findings are equivocal regarding relations between older maternal age and postpartum depression with some suggesting older mothers do not differ from their younger counterparts (Carolan, 2005; Windridge and Berryman, 1999) while others report higher depression scores (Boivin et al., 2009). It is difficult to compare findings across studies. Age-cut-offs at which women are deemed “older” have shifted from women aged above 30 (e.g., Gottesman, 1992) to more recent reports considering first time mothers over 40 (e.g., MacDougall et al., 2012; Vaughan et al., 2014). Comparability of findings is also limited by different approaches to measuring depression, with most studies relying

C.A. McMahon et al. / Journal of Affective Disorders 175 (2015) 454–462

on symptom checklists, although some report clinically significant depression based on diagnostic interviews. This latter approach has more stringent requirements that symptoms impair functioning and prevalence is typically lower (Gavin et al., 2005). We have previously reported that in the current study sample there were no age differences in vulnerability to major depressive episodes in the first four months after birth (McMahon et al., 2011). The primary objective of the current paper is to extend these findings by examining whether older first time mothers are more at risk of episodes of major depression with later onset. Although postpartum depression has been defined in diagnostic manuals as an episode of depression with onset in the first four weeks after birth (DSMIV, DSMV), some have argued that more attention needs to be directed to later and more variable onset (Gavin et al., 2005; O’Hara and Wisner, 2014). There is evidence that depression symptoms are also prevalent in mothers of toddlers and preschoolers (McCue Horwitz et al., 2009; Najman et al., 2000) and it is possible that risk factors may be different than for early depression. For example, the impact of subsequent reproductive events and child characteristics may play a larger role. Thus our second objective is to examine the role of maternal, contextual, infant related, and social variables that may contribute to vulnerability to episodes of depression between four months and two years after birth. Belsky’s (1984) seminal model outlining characteristics of the mother, the child, and contextual factors as key determinants of adjustment to parenting provides the theoretical framework for the current research. Maternal characteristics related to the biological realities of ageing may be particularly salient for older first time mothers later in the postpartum period as they may feel pressure to try and conceive a second infant without delay. For those who have experienced fertility problems, re-engaging with the physical and emotional demands of Assisted Reproductive Technology (ART) treatment may be daunting and stressful. Although ART conception has not been associated with increased depression vulnerability in the early postpartum period (see Ross et al. (2011) for a systematic review), to our knowledge studies have not considered the impact of subsequent ART treatment, pregnancies and pregnancy losses on maternal mood. For those older mothers who do achieve a subsequent pregnancy there is a greater likelihood of potentially stressful pregnancy and obstetric complications (Carolan and Frankowska, 2011). More broadly speaking physical ill health has been associated with maternal depression vulnerability, but is rarely taken into account (Brown and Lumley, 2000; Small et al., 2003), and age-related limits to physical stamina (Bornstein et al., 2006; Mirowsky, 2002) may also contribute to vulnerability, particularly when parenting an active toddler. On the other hand from a developmental perspective, Bornstein et al. (2003) have proposed that the more mature psychological capacities associated with older maternal age may be protective. Qualitative studies have consistently noted that older mothers report a greater sense of preparedness, competence, self-awareness and resilience, along with a flexible problem solving capacity (Berryman et al., 1995; Carolan, 2005). Maternal hardiness (Kobasa et al., 1982), a personality trait associated with resourcefulness, flexibility and a sense of internal control in the face of change has been reported to be higher in older mothers and associated with more positive psychological adjustment during pregnancy and the transition to parenthood (Camberis et al., 2014). In this paper we examine whether this maternal characteristic may be protective against later onset depression. A mother's prior history of mood problems also needs to be considered. Self-rated reports of depression symptoms in pregnancy have been consistently identified as the strongest predictor of vulnerability to postpartum depression (Scottish Intercollegiate Guidelines Network, 2012; Schmied et al., 2013) and women who

455

report elevated symptoms in the early postpartum period have an increased risk of persistent depression over a substantial period of time (Beeghley et al., 2002; Mora et al., 2009). In keeping with Belsky's model the current study also considers child characteristics. It is possible that the infants of older first time mothers provide more parenting challenges as the biological risks associated with older maternal age increase the likelihood of preterm birth and/or low birthweight. A recent review indicates that children born pre-term show more behaviour problems as well as poor social interactive skills and emotional self-regulation in the early years (Arpi and Ferrari, 2013). ART conception has also been linked with maternal help seeking related to unsettled infant behaviour in the early months after birth (Fisher et al., 2012), and older mothers have reported greater infant maladjustment and perceptions of infants as challenging (Bornstein et al., 2006). Several studies have shown that infant temperament characteristics, particularly excessive and inconsolable crying are associated with elevated maternal depression and anxiety symptoms (McGrath et al., 2008; Lin and McFatter, 2012; Radesky et al., 2013), although the direction of effect may be difficult to determine (Papousek and Von Hofacker, 1998). In addition to irritability and excessive crying, the construct of difficult temperament includes other traits challenging to parents such as low tolerance/co-operation with caretaking (bathing, dressing) and poor adaptation to novel situations and people (Sanson et al., 1985). The personal, family and social context of early parenthood is also different for older mothers. Lower maternal education has been identified as a risk factor for postpartum depression in some studies (Schmied et al., 2013; Mora et al., 2009) so the higher education, professional status and financial security typical of older mothers may be protective (Berryman et al., 2005; Carolan and Frankowska, 2011). Engagement in paid work is generally associated with better psychological wellbeing (Stansfield et al., 2008), but data from a nationally representative Australian cohort of mothers has shown that working in poor quality jobs is associated with greater psychological distress in postpartum women (Cooklin et al., 2011). Older mothers who may have more high status, flexible jobs may therefore be less vulnerable in this regard, but it is also possible that the heightened professional responsibilities may add to their stress levels (Bouchard et al., 2008). Inadequate social and partner support, and life event stresses are consistently identified as primary risk factors for early postpartum depression (Scottish Intercollegiate Guidelines Network, 2012; O’Hara and Wisner, 2014; Schmied et al., 2013). It has been suggested that older mothers may receive less informal support from family and peers (Morgan et al., 2012; Suplee et al., 2007). While some have suggested older parents may have more stable relationships (Berryman et al., 1995), others have pointed to more complex partnership issues related to second unions with men who already have children and/or short duration relationships prior to conceiving (Bouchard et al., 2008; Guedes and Canavarro, 2014). Finally we consider recent adverse life events identified as a primary risk factor for postpartum depression (Scottish Intercollegiate Guidelines Network, 2012) and migrant background. Recent census data indicates that 27% of the Australian population was born overseas (Australian Bureau of Statistics, 2012) and culturally and linguistically diverse women may be vulnerable to mental health problems in the perinatal period due to financial hardship, home-sickness, social isolation, lack of family support and language difficulties, that might compromise their capacity to access services and supports, with refugee women particularly vulnerable (beyondblue, 2011). In summary the current study had two aims. First we sought to determine whether older first-time mothers were more likely to experience clinically significant episodes of depression between

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four months and two years postpartum. Whilst older maternal age is associated with both risk and protective factors, in the context of negative anecdotal comment and media representations the hypothesis that older mothers would be more likely to experience later onset depression was tested. The second aim was to examine risk factors associated with episodes of later onset depression in the first postpartum year, drawing on Belsky's model for the determinants of parenting. Based on prior research it was hypothesized that a greater likelihood of depression would be associated with the following risk factors: 1) Maternal: (a) reports of elevated mood symptoms in pregnancy and the first four months after birth, (b) more health problems, (c) lower maternal hardiness 2) Child: (a) reports of difficult infant temperament and (b) reports of poor child health 3) Fertility context: (a) subsequent pregnancy, birth and/or ART treatment (b) subsequent pregnancy losses 4) Social context: (a) low education, (b) unsupportive partner relationship; (c) poor social support, (d) migrant background (d) stressful life events in the first four months after birth. Participation in paid work was also considered, but a directional hypothesis was not proposed due to mixed empirical evidence.

2. Method 2.1. Participants Participants were women enrolled in the Parental Age and Transition to Parenthood Australia (PATPA) study. Older first time mothers and mothers conceiving through ART were over-sampled relative to population levels. Approximately half the sample was recruited through ART clinics in two large Australian cities, and the remainder at private and public hospital antenatal clinics and classes in the geographic vicinity of the ART clinics. Inclusion criteria were as follows: nulliparous women in the third trimester of pregnancy with adequate English to complete study measures. 2.2. Procedures Approval was granted from all relevant institutional ethics committees. Women who consented participated in a structured telephone interview, providing detailed demographic and pregnancy context information and completed validated self-report questionnaires at: third trimester of pregnancy (M ¼ 31.6 weeks, SD ¼2.5 weeks); four months postpartum (M ¼4.78 months, SD ¼0.85 months); and when their child was approaching their second birthday (“toddler assessment”, M¼22.48 months, SD ¼3.51 months). At each postpartum assessment a diagnostic interview was administered to identify clinically significant episodes of major depressive disorder, and mothers also completed questionnaires. Demographic information was updated at each assessment and at the toddler assessment details of any ART treatment, pregnancies, pregnancy losses, and births since the previous contact at four months postpartum were recorded. 2.3. Measures 2.3.1. Outcome variable: major depressive episode after 4 months The Major Depressive Episode module from the Mini International Neuropsychiatric Interview (MINI version 5, Sheehan et al., 1998) was administered by telephone at four months and at the toddler assessment. This structured diagnostic interview yields

DSM-IV and ICD-10 classifications for psychiatric disorders, has been shown to be reliable and valid when compared with longer structured psychiatric interviews, for example, the CIDI and the SCID-P (Lecrubier et al., 1997) and has acceptable levels of interrater and test-retest reliability (Sheehan et al., 1998). Wording was modified so that participants were asked about depressive symptoms experienced since the birth of their child (four month interview, MDE1) and in the intervening time since the four-month contact (toddler interview, MDE2). In this paper we focus on episodes of depression reported between the four-month and the toddler assessment, but also report on overall prevalence (any episode between birth and two years) and recurrence/persistence (those who reported episodes of depression in both the first four months and also between four months and the toddler contact).

2.3.2. Maternal variables Maternal age was the primary focus of the study and three agegroups were defined as follows: “young”, women aged 20–30 years; “middle”, women aged 31–36 years, and “older”, women 37 years or older at the time of the first birth. Our definition of “older” was based on evidence that fertility rates decline exponentially after the age of 37 years (Gleicher et al., 2007). This group was the reference group for testing study hypotheses. We also considered ART conception for the first child, and maternal education assessed using a dichotomous variable (10 years or less of schooling no/yes). Hardiness was assessed using the Personal Views Survey 3rd edition (Maddi and Khoshaba, 2001). The questions assess capacity to transform stressful experiences into opportunities for learning on three dimensions: commitment, control and challenge. Anxiety and depression symptoms were assessed at 30 weeks gestation in pregnancy and at four months postpartum. The Edinburgh Postnatal Depression Scale is a 10 item questionnaire validated to assess depression symptoms in pregnancy and the postpartum period; a cut-off score of Z13 is considered likely to indicate clinically significant depressive symptoms (Cox et al., 1987). The State-Trait Anxiety Inventory (Spielberger et al., 1983); comprising two 20 item scales assessing how anxious women generally and currently felt, was used to assess trait anxiety in pregnancy and state anxiety at both contacts. Maternal health was assessed with a single question from the SF-36 (Ware and Sherbourne, 1992) at four months postpartum, ‘In general, would you say your health was: poor, fair, good, very good or excellent' (rated from 1 to 5). This question has been validated in epidemiological research with objective measures of health (Stewart et al., 1988), is sensitive to ongoing health-related problems, and is associated with symptoms of physical functioning and well-being (Schytt and Waldenstrom, 2007).

2.3.3. Child variables The 30-item Short Temperament Scale for Infants (Sanson et al., 1985), a well validated questionnaire was completed by mothers at four months. Items refer to how typically an infant responds in a particular way, and are rated on a Likert scale: 1 (almost never) to 6 (almost always). A composite difficulty score (Easy Difficult Score EDS) is derived by averaging scores from three subscales: Approach (response to novel people or places), Co-operation (behaviour during caregiving) and Irritability (negative affectivity and crying). The EDS has 18 items, and Cronbach's alpha¼ 0.79 in the current study. Higher scores indicate a more difficult temperament. Infant health in the first four months was assessed using a similar question to the single item for maternal health described above ‘Overall, is your baby's health: poor, fair, good, very good or excellent’ (rated 1 to 5). Infant age (in months) at toddler assessment was also considered.

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2.3.4. Contextual variables 2.3.4.1. Reproductive context. Detailed information was collected at the toddler assessment regarding subsequent reproductive events. Subsequent ART treatment after the first birth was coded dichotomously (no/yes) as were subsequent pregnancies, births, any pregnancy losses, and twins (first birth). 2.3.4.2. Social context. Education was classified dichotomously 410 years of schooling (yes/no). To assess intimate partner support, we used the Control subscale (12 items that index criticism/restriction of freedom) from the Intimate Bonds Measure (Wilhelm and Parker, 1988), completed four months after birth as this dimension has been most closely linked to mood in the perinatal period (Wynter et al., 2013). As scores above the 90th centile have been associated with mental health problems in women (Fisher et al., 2010), we generated a categorical variable with three levels: 0 (no partner); 1 (partner low on control,o90th centile); 2 (partner high on control, Z90th centile) so that women without partners could be retained in the analysis. A single interview question was used to assess overall satisfaction with practical support with housework and infant care from a variety of sources at four months (e.g., partner, friends, paid help). Mothers rated support on a scale from 1–5 with higher scores indicating more support. Mothers also answered at four-months a single item question (no/yes) about adverse life events in the first four months after birth, and whether or not they had any paid work. Finally participants indicated whether they spoke a language other than English at home, a variable that typically indicates immigrant background in Australian samples (dichotomous no/yes). 2.4. Data analysis Less than 5% of all questionnaire item responses were missing and they were prorated. The depression symptom measures (EPDS) in pregnancy and postpartum, and single item maternal health, infant health and satisfaction with social support ratings were skewed and square root transformations were applied. Analyses include transformed scores, but descriptive statistics present untransformed values. Bivariate analyses (ANOVA, chi-square) were used to compare age groups on all potential risk variables, and correlations (Pearson, product moment) show bivariate associations with depressive episodes between 4 months and two years. To test the primary study hypothesis regarding differences in maternal depression related to maternal age-groups we first ran a chi-square analysis to examine unadjusted depression rates by age-group. Given the strong association between maternal age and use of ART, a logistic regression model was then tested including age, ART conception and their interaction term (age  mode of conception). Finally to address the second objective to determine the best predictors of episodes of depression between four months and two years a logistic regression model was tested that included age and ART conception along with maternal, child and contextual variables that had significant or marginally significant (p o0.10) bivariate associations with episodes of depression between four months and two years.

3. Results 3.1. Attrition analyses Of the 592 women who participated in the pregnancy assessment, 434 (73%) completed all study measures for both the fourmonth and toddler assessment. Compared to women lost to follow up, women who participated in all three stages were significantly more likely to have conceived through ART (p ¼0.001), and to be in the middle (p ¼0.034) or older (p ¼0.012) age-groups. Women

457

retained in the sample did not differ with respect to partner status, education, involvement in paid work, nor likelihood of meeting diagnostic criteria for depression at the four month follow-up, all ps 40.10. 3.2. Sample characteristics: Maternal age-group comparisons on study variables Table 1 summarizes study variables according to maternal agegroup and indicates that the sample overall was socio-economically advantaged: few (5%) had low education, and 96% had a partner. Most (82%) spoke only English at home. At the time of the 2-year follow-up, most (71%) were involved in some paid work; 42% reported a subsequent pregnancy and 11% had a second baby. There were few age-group differences: likelihood of ART treatment (ART conception for first birth, and also subsequent ART treatment) was highest for the older age group and higher for mid-age mothers than younger mothers; older mothers were less likely than mothers in the middle and youngest age-group to report a subsequent pregnancy and/or birth, and more likely to report at least one stressful life event in the first four months. Younger mothers scored lower than mid-age and older mothers on hardiness and infants of mothers in the younger age-group were older than infants of mothers in the other two age-groups at the time of the toddler assessment, all ps o0.05 (Table 2). 3.3. Age-related prevalence of episodes of major depressive disorder The primary hypothesis examined whether older mothers were more likely to report late onset episodes of depression. Overall, there were no age differences with regard to prevalence or timing of depressive episodes, ps 40.10. Because of the close association between age and ART conception, a logistic regression analysis for depression likelihood was conducted including age, mode of conception and their interaction effect. All were non-significant, ps¼0.10. Of the total sample (N ¼ 434), 36 women (8.3%) reported an episode of depression meeting diagnostic criteria in the first four months and 43 (9.9%) reported an episode between 4 months and the toddler assessment. Nine women (25% of those depressed in the first four months and 2.1% of the total sample) reported episodes meeting criteria on both occasions. 3.4. Predictors of major depressive episodes between four months and two years The second objective was to test whether various hypothesized risk variables predicted later onset depressive episodes and to determine the best predictive model, including both age and mode of conception. Table 1 also includes zero-order and point bi-serial correlations with later onset depressive episodes. The variables that showed significant (or trend) correlations included maternal factors (depression and anxiety symptoms in pregnancy and at four months, trait anxiety in pregnancy, maternal hardiness), child factors (difficult temperament and less optimal child health in the first four months), and social contextual factors (language other than English spoken at home, lower satisfaction with social support and stressful life events at four months). None of the reproductive context variables was associated with later onset depression. A final logistic regression analysis including age, mode of conception and all variables with significant or marginal bivariate associations was conducted. Significant predictors of episodes of depression between four months and two years were higher depression symptoms at four months (OR¼ 1.23, 95% CI 1.07,1.38), less optimal baby health in the first four months (OR¼0.16, 95% CI¼ 0.03, 0.88), mothers who spoke a language at home other than English (OR¼2.37, 95%

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Table 1 Descriptive statistics by maternal age-group and bivariate correlations with episode of major depression between 4 months and two years (MDE2). Z 30 years (n¼ 117) “Younger”

31–36 years (n¼165) 4 37 years “Middle” (n¼ 152) “Older”

Total (n¼ 434)

28.2 (1.6)a 35.0 (41)a

33.6 (1.8)b 50.9 (84)b

39.3 (2.1)c 73.0 (111)c

34.1 (4.7) (2) 117nnn 54.4 (2) 39.7nnn (236)

Hardiness M (SD)

38.9 (5.2)a

40.5 (5.8)b

41.4 (5.6)b

40.4(5.6)

(2) 7.0nn

 0.11n

Health (4 months postpartum) M (SD) EPDS pregnancy M (SD) EPDS 4 months postpartum M (SD) Trait anxiety pregnancy M (SD) State anxiety pregnancy M (SD) State anxiety 4 months postpartum M (SD)

3.9 (1.0)

3.8 (0.9)

3.8 (1.1)

3.8 (1.0)

ns

 0.09δ

5.1 (3.8) 5.2 (4.3)

5.0 (4.5) 4.9 (3.8)

4.9 (4.6) 4.8 (4.2)

5.0 (4.3) 5.0 (4.1)

ns ns

0.09δ 0.27nn

34.0 (7.7) 31.4 (7.7) 30.6 (8.3)

33.9 (9.2) 31.8 (9. 6) 30.0 (8.4)

33.3 (8.2) 31.2 (8.4) 31.1 (8.6)

33.7 (8.3) ns 31.5 (8.6) ns 30.5 (8.3) ns

0.11n 0.09a 0.21nn

2.4 (0.5)

2.3 (0.6)

2.4 (0.5)

0.16nn

23.2 (3.6)b

22.2 (3.4)b

22.5 (3.5) (2)6.8nn

 0.01

4.7 (0.6)

4.8 (0.5)

4.7 (0.6)

ns

 0.19nn

3.4 (4) 47.9 (56)a

4.2 (7) 45.5 (75)a

5.9 (9) 34.2 (52)b

ns (2) 6.2n

.04  0.02

11.1 (13)a

9.1 (15)a

17.1 (26)b

4.6 (20) 42.2 (183) 12.4 (54)

(2).92δ

-.05

5.9 (9) 13.2 (20)b

10.8 (47) 9.2 (40)

n

(2) 5.8 (2) 6.2n

0.01  0.05

Maternal Age M (SD) ART % yes, (n)

Child Difficult temperament at four- 2.4 (0.5) months M (SD) Age (months) at follow-up M 21.7 (3.3)a (SD) Health (4 months postpartum) 4.7 (0.7) M (SD) Context (Fertility related) Firstborn twins % yes (n) Subsequent pregnancy % yes (n) Pregnancy loss after first % yes (n) Subsequent birth % yes (n) Subsequent ART % yes (n) Context (Social) o grade 10 education % yes, (n) Language other than English % yes, (n) Partner controlling/single‡ % yes (n) Paid work % yes (n)

13.7 (16) 4.3 (5)a

a

13.3 (22) 9.1 (15)b

a

b

Age-group comparisons (df) and F values or χ2

ns

Zero order/Product moment correlations with MDE2

0.01  0.02

7.7 (9)

3.0 (5)

5.9 (9)

5.3 (23)

ns

0.02

21.4 (25)

17.0 (28)

12.5 (19)

16.6 (72)

ns

0.08δ

9.4 (11)

10.3 (17)

15.1 (23)

11.8 (51)

ns

0.07

65.0 (76)

75.8 (125)

29.7 (106)

ns

 0.02

27.3 (45)

27.0 (41)

ns

 0.19nn

33.9 (56)a

42.8 (65)b

70.7 (307) 24.2 (105) 35.7 (155)

(2) 5.7δ

0.09δ

Dissatisfied social support 16.2 (19) 4 months % yes (n) Stressful life events 4 months % 29.1 (34)a yes (n) Note: a,b indicate significant differences between age-groups. ‡

20 women (3.6%) did not have a partner. indicates significant at p o0.05. nn p o01. nnn p o0.001. δ indicates trend, p o 0.10; df relates to F tests and Chi-square Analyses. n

CI¼1.01, 5.57), and reports of less satisfaction with practical support at four months (OR¼0.24, 95% CI¼0.07, 0.80), see Table 3. Subsequently we examined the profile of the nine women who met diagnostic criteria for major depressive episodes at both follow-up points. The only variables that differentiated them from those not depressed, and those depressed at only one follow-up interview were significantly higher depression and anxiety symptoms at four months (ps ¼0.000), see Table 4.

4. Discussion There is very little empirical evidence about the psychological wellbeing of older first-time mothers, and negative, generally unsubstantiated views of older mothers as “difficult”, “anxious”,

“selfish” are common (Carolan, 2005; Cooke et al., 2012; Shaw and Giles, 2009). From a medical perspective there has been a focus on the risks of delayed childbearing including declining fertility, fertility treatment and increased risk of adverse perinatal outcomes for mother and baby (Berryman et al., 1995; Schmidt et al., 2012). Consequently, the primary aim of this study was to examine whether older first time mothers were particularly vulnerable to clinically significant depression over the first two years after birth, taking account of many of these age-related biological risks as well as psychosocial protective factors that may characterize older mothers. Results indicate that older first time mothers have rates of clinically significant depression in the first two years after birth that are comparable to their younger counterparts of a similar socioeconomic background. The growing trend to later childbearing in contemporary developed societies may have contributed to reduced

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459

Table 2 Numbers (%) of women meeting diagnostic criteria for Major Depressive Episodes (MDE) according to maternal age-group and mode of conception. Mode of Conception

Younger 20–30 years n ¼117

Middle 31–36 years n¼ 165

Older Z 37 years n¼ 152

(n¼ 434)

3/81 (3.7) 10/84 (11.9) 13/165 (7.9)

5/41 (12.2) 7.111 (6.3) 12/152 (7.9)

16/198 (8.1) 17/236 (8.5) 36/434 (8.3)

Major depressive episodes between four months and two years only (MDE2) N (%) SC 6/76 (7.9) 8/84 (9.9) ART 3/41 (7.3) 9/84 (10.7) Total 9/117(7.7) 17/165 (10.3)

5/41 (12.2) 7/111 (9.0) 12/152 (7.9)

21/198 (10.6) 22/236 (9.3) 43/434 (9.9)

Major Depressive Episodes at both four months and two years follow-up N (%) SC 2/76 (2.6) 1/84 (1.2) ART 1/41 (2.4) 1/84 (1.2) Total 3/117 (2.6) 2/165 (1.2)

2/41 (4.9) 2/111(1.8) 4/152 (2.6)

5/198 (2.1) 4/236 (1.7) 9/434 (2.8)

Major depressive episodes in first four months only (MDE1) N (%) SC 8/76a (10.5) ART 3/41 (7.3) Total 11/117(9.4)

Total

a

Note: a

Because cell sizes vary, for ease of interpretation, numbers are expressed in relation to cell size, e.g., 8/76 indicates 8 of the 76 younger SC women, etc.

Table 3 Predictors (Logistic Regression) of major depressive episode(s) between 4 months and two years postpartum. Predictor

B (S.E.)

Wald (df)

P value

Exp (B)

95% CI

Maternal Age-group at first birth Middle (31–36) vs older ( 437 years) Younger (20–30) vs older ( 437 years) ART conception Hardiness Health (4 months postpartum) EPDS pregnancy EPDS 4 months postpartum Trait anxiety pregnancy State anxiety pregnancy State anxiety 4 months postpartum

 0.22 (.43)  0.67 (.53)  0.18 (0.38)  0.04 (0.04)  0.41 (0.61) 0.05 (0.06) 0.20 (0.06)  0.03 (0.04)  0.03 (0.03)  0.01 (0.03)

1.64 (2) 0.25 (1) 1.61 (1) 0.22 (1) 0.96 (1) 0.45 (1) 0.50 (1) 9.32 (1) 0.50 (1) 0.59 (1) 0.18 (1)

0.440 0.615 0.204 0.641 0.328 0.504 0.481 0.002 0.480 0.440 0.670

0.81 0.51 0.84 0.96 0.66 1.05 1.23 0.97 0.97 0.99

0.35–1.87 0.18–1.44 0.39–1.76 0.89–1.04 0.20–2.20 0.92–1.20 1.07–1.38 0.89–1.05 0.91–1.04 0.92–1.05

Child Difficult temperament at four-months Health (4 months postpartum) M (SD)

0.32 (.36)  1.84 (.88)

0.78 (1) 4.41 (1)

0.378 0.036

1.38 0.16

0.67–2.82 0.03–0.88

Context (Social) Language other than English Dissatisfied with social support 4 months Stressful life events 4 months

0.86 (0.43)  1.42 (0.61) 0.24 (.37)

3.95 (1) 5.43 (1) 0.43 (1)

0.047 0.020 0.513

2.37 0.24 1.28

1.01–5.57 0.07–0.80 0.61–2.66

Table 4 Symptom scores at four months according to pattern of response regarding major depressive episodes (MDE). Symptoms 4 Months

Depression Group MDE (n)

Mean

SD

No MDE (365) MDE early only (27) MDE later only (33) MDE early, late (9) Total (434)

4.49a 6.15a 7.15b 12.89c 4.96

3.75 5.21 3.49 4.80 4.09

No MDE (365) MDE early only (27) MDE later only (33) MDE early, late (9) Total (434)

29.76a 32.76a 35.16b 39.24c 30.55

7.98 9.58 7.00 12.03 8.33

EPDS

A-State

Note: Alphabetical superscripts indicate significant differences between depression groups.

feelings of difference or stigma for older mothers (Mills and Lavender, 2014). In addition, advances in health, medical knowledge, preventative health behaviors and obstetric practice may have

helped to offset the impact of biological risk (Carolan and Frankowska, 2011; Dickinson, 2012). The second objective was to explore risk factors for later episodes of depression. Women were at increased risk if at four months they had high symptom scores for depression, rated their infant's health as suboptimal, reported less than optimal practical support and spoke a language other than English in the home. In keeping with Belsky's model of determinants of parenting, and bearing in mind the developmental challenges as infants become more mobile and autonomy seeking toddlers, we proposed that child factors might be important contributors to vulnerability for later onset depression. Both difficult child temperament and poorer child health at four months were associated with later depression episodes as predicted, but when considered together, it was sub-optimal child health that increased the likelihood of later depression. Infants differ in the caretaking challenges they pose and those with health difficulties may be poor sleepers and difficult to console when distressed, as well as a source of ongoing maternal worry about their developmental outcomes. Mothers and infants reciprocally influence each other and dysregulated infant behaviour and inconsolable crying can undermine maternal feelings of self-efficacy (Papousek and von

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Hofacker, 1998). Further, infants with these characteristics might provide the mother with few rewards for her caretaking efforts, potentially contributing to feelings of helplessness and depression (Radesky et al., 2013). However, several caveats apply to the interpretation of our findings related to poor child health. First, because our sampling method excluded women who gave birth prior to 28 weeks gestation, the findings may be conservative, as very premature infants who may present the most salient parenting challenges (Arpi and Ferrari, 2013) were not included. Second, despite the large sample, most mothers reported their infants had optimal health, so further research examining depression vulnerability in mothers of infants with significant health problems in the early months after birth is needed. Elevated depression symptoms in the first four months were the strongest predictor of later depression, consistent with several prior prospective studies in first-time mothers at low socio-economic risk (Beeghly et al., 2002; McMahon et al., 2005), and also with a large body of research indicating that prior mood problems are the strongest predictor of postpartum depression vulnerability (Scottish Intercollegiate Guidelines Network, 2012, Schmied et al., 2013). These findings indicate a need for close monitoring and follow-up of women who present with more severe symptoms in the early months as women with recurrent and persistent depression are most at risk for parenting difficulties and compromised child outcomes (Campbell et al., 2007; Vanska et al., 2011). With regard to the social context of motherhood, our finding that low social support at four months predicted later depression episodes is consistent with a considerable evidence base that poor social support is a risk for onset of depression early in the postpartum period (Scottish Intercollegiate Guidelines Network, 2012; Schmied et al., 2013). In contrast with some previous evidence that older mothers may have more limited support from partners (Boivin et al., 2009) and social networks (Bornstein et al., 2006; Morgan et al., 2012) older and younger mothers in the current study did not differ from their younger counterparts in their reports of practical support from partner and others at four months. A more comprehensive approach to assessing social support would be appropriate in future studies. Our finding that women speaking a language other than English had an increased likelihood of depression further confirms the importance of considering the social cultural context of mothering. In an Australian context, prior research with immigrant women from non-English speaking backgrounds has shown that isolation (including homesickness) is strongly and consistently associated with depression in these groups (Small et al., 2003) and language difficulties may compromise capacity to access services and support networks (beyondblue, 2011), however as we did not investigate migrant status and capacity to access supports in depth, these interpretations are speculative. There was no evidence to support that hypothesis that fertility related difficulties, and age-related maternal health problems might contribute to depression risk, particularly for older mothers. Almost half the women reported a subsequent pregnancy, but only 10% had a second child and older mothers were significantly less likely than their younger counterparts to have experienced a subsequent pregnancy or birth. In addition, ART conception (for first or subsequent pregnancy) did not predict likelihood of depression adding to accumulating evidence that women conceiving through ART are not more vulnerable to depression after childbirth (Ross et al., 2011; Vanska et al., 2011). It was also proposed that older mothers might have more health difficulties, which may in turn make them more likely to experience depression, but comparable levels of health were reported across the age-groups. Women with substantial socioeconomic resources may have good access to health care and participate in health promoting activities that offset age-related vulnerability.

This study also considered characteristics of older first time mothers that might be protective. Qualitative studies have consistently reported that older mothers describe benefits related to their age, with regard to maturity, emotional readiness, and self-awareness that may be helpful in adjusting to parenthood (Berryman et al., 1995; Carolan, 2005). Accordingly, we examined whether higher levels of the personality attribute of hardiness, an adaptive capacity to respond flexibly to life's challenges, might be protective. While hardiness was associated with more positive adjustment to pregnancy and subjective experiences of early motherhood in this sample (Camberis et al., 2014), when all risk factors were considered together, this personality trait did not influence the likelihood of clinically significant depression. 4.1. Strengths and limitations Study strengths include the large sample, the rigorous assessment of depression over a two year period, the consideration of important risk and protective factors that may be confounded with maternal age, particularly the use of ART, and the inclusion of a broad range of maternal, child and contextual factors. Several limitations need to be acknowledged, however. While the sample size was large, we were unable to adequately explore vulnerability to recurrent depression. We considered maternal biological risk, and used the construct of hardiness to index personal competencies that might be associated with older age, but other maternal characteristics such as life history of mental health problems (Beeghly et al., 2002), and caregiving and relationship history were not assessed. Further, while inferences are drawn about cultural isolation based on language spoken at home a comprehensive assessment of cultural factors and immigrant status was not conducted. We were not able to differentiate women from refugee backgrounds, and we acknowledge that while English language difficulties may present particular challenges in accessing services and support, many recent migrants in Australia may be English speakers. The use of a validated diagnostic interview to assess depression is a strength, and provides information regarding clinically significant depression, however depression symptoms at the toddler interview were not assessed, so we were unable to explore subclinical depression or profiles of symptomatology over time. Finally the relatively homeogenous socio-demographic characteristics of our volunteer sample, the fact that we did not sample adolescent mothers, and the relatively small number of women in their middle or late forties limit conclusions that can be drawn about depression risk in mothers having a first baby at more extreme ends of the childbearing age-range. 4.2. Conclusions A range of influences and circumstances can contribute to delayed childbearing, often neither a deliberate nor a preferred choice (Cooke et al., 2012; MacDougall et al., 2012). Results of this study indicate that older mothers are not at greater risk of major depression episodes in the first two years after birth and should not, therefore, be labeled or stigmatized. Negative stereotypes may contribute to compromised health care and maternal anxiety and distress, if health professionals pre-judge older mothers as needy and/or demanding (Carolan, 2005; Gleicher et al., 2007; Pennings, 2013; Shaw and Giles, 2009). The prevalence of depression ( 10%) is at the low end of the range reported in previous longitudinal Australasian samples (Schmied et al., 2013), but consistent with the lower rates when a diagnostic interview is used to identify clinically significant depression (Gavin et al., 2005). This relatively low prevalence is also consistent with the high socio-economic status of the sample;

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most women were highly educated and partnered and this may offset some of the stresses inherent in the transition to parenthood. While results are reassuring in the context of older first-time parenthood, rates of depression comparable to community rates indicate that despite socio-economic protective factors, women from these backgrounds are not immune to mood disorders after childbirth (Sutter-Dallay et al., 2012) and confirm the importance of identifying and supporting vulnerable women, particularly those with high symptom levels in pregnancy and the first few months after birth. Finally, findings demonstrate that women are just as likely to report episodes between four months and two years as in the first few months postpartum. Our finding that symptom severity at four months is the strongest risk factor for later episodes of depression suggests that screening for depression should be ongoing and not restricted to the early months after birth.

Conflict of interest The authors report no conflict of interest.

Role of funding source The Australian Research Council (ARC) provided funds for research staff and costs. Partner Investigators (IVF Australia, Melbourne IVF) provided in kind support for recruitment of participants and also provided cash towards research costs.

Acknowledgments The project was funded through an Australian Research Council (ARC) Linkage Grant with financial contributions from private IVF Clinics (IVF Australia and Melbourne IVF) as linkage industry partners. Thanks to Dr Alan Taylor for assistance with statistical analyses.

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