Maternal postnatal psychiatric symptoms and infant temperament affect early mother-infant bonding

Infant Behavior & Development 43 (2016) 13–23

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Infant Behavior and Development

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Maternal postnatal psychiatric symptoms and infant temperament affect early mother-infant bonding Nolvi Saara a,∗ , Karlsson Linnea a,c , Bridgett David J. b , Pajulo Marjukka a,d , Tolvanen Mimmi a , Karlsson Hasse a,e a b c d e

The FinnBrain Birth Cohort Study, Turku Brain and Mind Center, Department of Clinical Medicine, University of Turku, Finland Department of Psychology, Northern Illinois University, United States Department of Child Psychiatry, Turku University Hospital, Finland Academy of Finland, Finland Department of Psychiatry, University of Turku, Finland

a r t i c l e

i n f o

Article history: Received 19 April 2015 Received in revised form 13 September 2015 Accepted 29 March 2016 Keywords: Temperament Postnatal depression Anxiety Mother-infant bonding Infancy Maternal postnatal depressive and anxiety symptoms Infant temperament and mother-Infant bonding

a b s t r a c t Postnatal mother-infant bonding refers to the early emotional bond between mothers and infants. Although some factors, such as maternal mental health, especially postnatal depression, have been considered in relation to mother-infant bonding, few studies have investigated the role of infant temperament traits in early bonding. In this study, the effects of maternal postnatal depressive and anxiety symptoms and infant temperament traits on mother-infant bonding were examined using both mother and father reports of infant temperament. Data for this study came from the first phase of the FinnBrain Birth Cohort Study (n = 102, father reports n = 62). After controlling for maternal symptoms of depression and anxiety, mother-reported infant positive emotionality, measured by infant smiling was related to better mother-infant bonding. In contrast, infant negative emotionality, measured by infant distress to limitations was related to lower quality of bonding. In regards to father-report infant temperament, only infant distress to limitations (i.e., frustration/anger) was associated with lower quality of mother-infant bonding. These findings underline the importance of infant temperament as one factor contributing to early parentinfant relationships, and counseling parents in understanding and caring for infants with different temperament traits. © 2016 Elsevier Inc. All rights reserved.

Postnatal bonding refers to a mother’s early emotional connectedness to her infant. Bonding starts developing during the prenatal period and continues to develop throughout the postnatal period (Salisbury, Law, LaGasse, & Lester, 2003). Underscoring the importance of early mother-infant bonding, bonding is related to children’s subsequent secure attachment (Bicking Kinsey & Hupcey, 2013) and to higher quality mother-child interactions, such as increased maternal responsiveness to infant cues (Hornstein et al., 2006). In turn, better child attachment and maternal parenting behaviors are important for development in a number of domains, including social competence, cognitive development and physical health (Campbell, Matestic, von Stauffenberg, Mohan, & Kirchner, 2007; Milgrom, Westley, & Gemmill, 2004; Murray, Fiori-Cowley, Hooper, & Cooper, 1996; Ranson & Urichuk, 2008). Given the importance of early bonding, understanding what factors may influence early bonding has implications for basic science and applied interventions.

∗ Corresponding author. E-mail address: saara.nolvi@utu.fi (S. Nolvi). http://dx.doi.org/10.1016/j.infbeh.2016.03.003 0163-6383/© 2016 Elsevier Inc. All rights reserved.

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Existing work has demonstrated that the mother-infant relationship, including bonding, develops as a function of a number of factors. However, most existing research has focused on the effects of maternal characteristics on bonding. For instance, maternal depression has frequently been associated with poorer bonding (Hornstein et al., 2006; Müller, Teismann, Havemann, Michalak, & Seehagen, 2013). Less work has specifically considered the role of infant characteristics, such as temperament, in relation to maternal bonding, despite the recognized role of children’s temperament in relation to other aspects of the parent-child relationship (e.g. Dix & Yan, 2014). In light of the limited work that has considered infant temperament in relation to mother-infant bonding, the current investigation sought to examine relations between infant temperament and bonding while accounting for the influence of maternal anxiety and depressive symptoms. 1. Associations between infant temperament and mother-infant bonding Temperament refers to biologically-based individual differences in the domains of activity, affectivity, attention and self-regulation (Rothbart & Bates, 2006; Shiner et al., 2012). There is long-standing interest in relations between children’s temperament and their developmental outcomes (e.g., relations between child negative emotionality and later psychiatric symptoms; Kotelnikova, Mackrell, Jordan, & Hayden, 2014; Pluess & Belsky, 2010). Alongside interest in relations between temperament and children’s outcomes, there also is considerable interest in how children’s temperament characteristics may affect the contexts in which they are raised, including the parenting that they receive. For example, elevated infant negative emotionality appears to contribute to parent-child interaction difficulties (Stright, Gallagher, & Kelley, 2008; van den Bloom & Hoeksma, 1994), the quality of attachment (Calkins & Fox, 1992), parenting behavior (Belsky, 1984), and parenting stress (Oddi, Murdock, Vadnais, Bridgett, & Gartstein, 2013), which are phenomena closely related to bonding. Similarly, in older children, irritability (Lengua & Kovacs, 2005) or earlier negative emotionality (Bridgett et al., 2009; Laukkanen, Ojansuu, Tolvanen, Alatupa, & Aunola, 2014; Lengua & Kovacs, 2005; Sanson, Hemphill, & Smart, 2004) have frequently been related to non-optimal parenting. Although negative affect has been the most frequently considered temperament attribute in relation to parenting-related outcomes, there is some evidence that other temperament attributes may affect such outcomes. Kochanska, Friesenborg, Lange and Martel (2004) reported that laboratory assessed infant joy contributed to positive parent-child interactions. Other investigators have reported similar findings, with child positive emotionality and self-regulation being related to more positive parenting (Sanson et al., 2004) or eliciting less negative parenting behavior (Bridgett, Laake, Gartstein, & Dorn, 2013). Given some overlap between parent bonding and other parenting behaviors, such as those observed during parentinfant interactions (Hornstein et al., 2006; Noorlander, Bergink, & van den Berg, 2008) it might be anticipated that infant temperament would influence maternal bonding during the postpartum period. However, only two studies have specifically considered relations between infant temperament and early mother-infant bonding. Parfitt et al. (2014) found that infant difficult temperament was associated with lower quality of mother-infant bonding at 3 months postpartum for both mothers and fathers after adjusting for the quality of the couple’s relationship and parental mental health, as well as bonding at 15 months after controlling for earlier parent-infant bonding. In the only other study to specifically consider bonding, Edhborg et al. (2005) found that infant fussiness and negative affect were related to lower quality of bonding between mothers and their infants. Furthermore, lower quality of father-infant bonding was associated with infant unpredictability and dullness. In addition to the two studies that have considered infant temperament, several studies have considered infant attributes that are sometimes considered to be markers of difficult temperament. For example, lower quality of bonding has been associated with infant colic (Bicking Kinsey, Baptiste-Roberts, Zhu, & Kjerulff, 2014), which might share some common variance with infant negative affect (Canivet, Jakobsson, & Hagander, 2000; Lester, Zachariah Boukydis, Garcia-Coll, Hole, & Peucker, 1992; St. James-Roberts, Conroy, & Wilsher, 1998), and with infant sleep difficulties (Hairston et al., 2011), which has also been linked with infant irritability. Thus, these studies bolster the evidence of the potential role of infant temperament in the formation of mother-infant bonding. As the material briefly covered in this section illustrates, existing work that considers infant temperament in relation to parenting-related outcomes has primarily focused on infant negative affect and irritability. Few studies have investigated associations between positive emotionality and the parent-infant relationship (see Bridgett et al., 2013 and Sanson et al., 2004 for notable exceptions). Similarly, most of the current research has focused on relations between broad temperament constructs (e.g., negative emotionality) and bonding instead of considering relations between finer-grained aspects of temperament (e.g., fearfulness) and bonding. Moreover, the few studies that have considered relations between infant temperament and bonding have not used measures capable of differentiating relations between distinct temperament traits (e.g., positive and negative emotionality). These limitations are addressed in the current study. 2. Maternal mental health and mother-infant bonding In contrast to the scarcity of research considering relations between infant temperament and early maternal bonding, more numerous studies have reported associations between aspects of maternal mental health and the quality of early bonding. For example, postnatal depression (Bicking Kinsey & Hupcey, 2013; Hornstein et al., 2006; Müller et al., 2013) and depressive symptoms (Bicking Kinsey et al., 2014; Dubber, Reck, Müller, & Gawlik, 2014; Edhborg, Nasreen, & Nahar Kabir, 2011; Hairston et al., 2011; Moehler, Brunner, Wiebel, Reck, & Resch, 2006; Müller et al., 2013; Ohoka et al., 2014; Reck

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et al., 2006; Tietz, Zietlow, & Reck, 2014) have frequently been shown to deteriorate mother-infant bonding quality. This even holds true for milder, sub-clinical depressive symptoms (Edhborg et al., 2011; Tietz et al., 2014; Wittkowski, Wieck, & Mann, 2007). Relative to the larger body of work that has considered maternal depression, the effects of maternal anxiety on bonding have not been investigated as extensively, and those studies that have considered maternal anxiety have reported mixed findings. In one study, maternal anxiety symptoms were related to higher quality of mother-reported bonding (Edhborg et al., 2011), which the authors attributed to anxious mothers potentially being more sensitive to infant emotional cues compared to mothers with depression. In contrast, other studies have noted relations between higher maternal anxiety and lower bonding. However, the negative association between maternal anxiety and bonding quality in these studies was no longer significant after controlling for depressive symptoms (Dubber et al., 2014; Tietz et al., 2014). Nevertheless, Feldman, Greenbaum, Mayes and Schmuel (1997) reported that maternal postnatal trait anxiety was one of the most central factors interfering with mother-infant interaction when children were between the ages of 3 and 9 months, especially when combined with infant irritability. Thus, although there is some evidence that depression may play a more prominent role than anxiety in the hindrance of mother-infant bonding, other evidence supports the notion that both depression and anxiety may uniquely affect mother-infant bonding. Given the mixed evidence in the existing literature, we consider both maternal symptoms of depression and anxiety in the current investigation as factors that may affect mother-infant bonding. 3. Maternal mental health and infant temperament In addition to relations between maternal mental health and bonding, maternal mental health and infant temperament are also interrelated. Maternal postnatal depression is related to more infant irritability, reactivity and distress proneness (Beck, 1996, 2001; Bridgett et al., 2009; Eastwood, Jalaludin, Kemp, Phung, & Barnett, 2012; Hanington, Ramchandani, & Stein, 2010; McGrath, Records, & Rice, 2008). Likewise, there is evidence that maternal anxiety is also related to infant temperament (Britton, 2011; Della Vedova, 2014), though anxiety has received considerably less attention compared to depression in the existing literature. Moreover, anxious and depressed mothers might assess temperament differently compared to their peers (see Gartstein, Bridgett, Dishion, & Kaufman, 2009). In the bonding-related studies discussed earlier, Parfitt et al. (2014) controlled for previous parent mental health when examining temperament as a predictor of bonding, whereas Edhborg et al. (2005) did not specify the unique contributions of infant temperament to bonding. As maternal psychiatric symptoms contribute both to the experience of bonding and infant characteristics, such symptoms should be taken into account in studying associations between bonding and temperament. 4. The present study and the hypotheses Few studies have considered children’s individual difference characteristics, such as temperament, in relation to bonding. Moreover, of those few studies have that considered such a question, some do not account for maternal psychiatric symptoms, and most have only considered infant negative affect and irritability, and not a wider range of fine-grained infant temperament attributes that may be related to bonding. As such, the aim of this study was to examine the effects of finegrained infant temperament traits, covering both positive and negative emotionality, using both mother and father reports of temperament, and maternal depressive and anxiety symptoms on mother-infant bonding. On the basis of existing work, we anticipated that (1) maternal postnatal depressive symptoms, (2) maternal postnatal anxiety symptoms and (3) infant negative emotion attributes would be associated with lower quality of mother-infant bonding at six months postpartum. We also anticipated that (4) infant positive emotion attributes would be related to better mother-infant bonding six months postpartum. Finally, given the longstanding evidence of relations between maternal mental health and infant temperament, associations between maternal psychiatric symptoms and infant temperament were also considered. 5. Method 5.1. Participants This study consists of a sample of Finnish families from the first phase of the FinnBrain Birth Cohort Study. The sample was gathered between May and December 2010, with families recruited during the first trimester ultrasound visit (gestational week, gwk, 18–20) by a personal contact with a research nurse. Altogether, 203 families, including 147 fathers, agreed to participate. Of these families, 153 (75.4%) returned the first questionnaires. The sample used in the current study comprises mothers (n = 102; 66.7%) and fathers (n = 62; 42.2%) who returned the six-month study questionnaires. The mothers who dropped out had significantly higher depressive symptom scores (p = 0.016) and were more likely to have lower education (p < 0.001) than those retained in the study. There were no differences in the fathers who did not complete the study compared to the fathers who completed the study. In the current study, mothers’ mean age at mid-gestation was 29.9 years (SD = 4.9), 62.5% of mothers were primiparous, and 47.1% had a university degree. In turn, fathers’ mean-age at mid-gestation was 32.0 years (SD = 5.4) and 35.6% reported a university degree. Study participants came from a variety of economic backgrounds: a total of 21% of households reported

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Table 1 The means of mother-infant bonding at 6 months, EPDS score and STAI score at 3 months and mother- and father-reported infant temperament subscales at 6 months postpartum. Variable (theoretical range)

Mean

SD

Median

Q1

Q3

PBQ total sum (0–125) EPDS (0–30) STAI (20–80)

9.75 4.49 31.64

7.05 3.75 7.48

8.00 3.50 30.00

5 2 26.5

13 6.75 36

Mother-reported temperament (1–7) Activity level Fear Duration of orienting Smiling and laughter Soothability Distress to limitations

4.54 2.41 3.22 4.77 4.93 3.26

0.82 0.71 0.95 0.90 0.85 0.69

4.65 2.34 3.23 4.86 5.00 3.16

3.99 1.94 2.53 4.00 4.35 2.72

5.08 2.77 3.78 5.51 5.60 3.71

Father-reported temperament (1–7) Activity level Fear Duration of orienting Smiling and laughter Soothability Distress to limitations

4.52 2.36 3.04 4.72 4.53 3.30

0.72 0.66 0.82 0.91 1.00 0.66

4.53 2.27 3.00 4.80 4.50 3.25

4.00 1.87 2.46 4.22 3.90 2.81

4.97 2.73 3.62 5.33 5.24 3.74

Q1 = firstquartile, Q3 = thirdquartile.

that their yearly income was under 24,000D , suggesting that approximately 21% of families in the current study were living close to or below the poverty level based on the benchmark of 26,534D , the poverty line for Finnish families of three. Mean gestation length was 39.5 weeks (31.0–42.3 weeks, SD = 2.2). Mean weight of the infants was 3470 g (1885–5259 g, SD = 619). There were eight infants (7.7%) that were born premature either based on weight (<2500 g) or gestational weeks (<37 wks). In terms of sex, there were approximately equal numbers of male (51.0%) and female (49.0%) infants in the current investigation. 5.2. Procedures Data for this study was gathered via postal questionnaires at three time points. At the initial time point (gwk 18–20), mothers completed background information questions. After the babies in the sample were born, the hospital records containing information such as birth weight were collected. Next, at three months postpartum, mothers completed the Edinburgh Postnatal Depression Scale (EPDS) and the State and Trait Anxiety Inventory (STAI). Finally, six months postpartum, maternal reports of mother-infant bonding with the Postpartum Bonding Questionnaire (PBQ) and both mother and father reports of infant temperament with the Infant Behavior Questionnaire (IBQ) were obtained from January to December 2011. The Joint Ethics Committee of the University of Turku and South-Western Hospital District approved the study protocol. 5.3. Measures 5.3.1. Background information At the point of entry into the current study (gwk 18–20), families were asked about age, education, housing and income. Education was asked from both parents and measured on a scale from 1 to 8. In this study, participants were further divided into two groups, university degree (1) or no university degree (0) for the purposes of including this information in analyses. Household income per month was reported on a 1–5 scale (1 = ”under 1000”, 2 = ”1000–2000”, 3 = ”2000–3000”, 4 = ”3000–4000” and 5 = over 4000” euros). The percent of participants reporting each income level is used in the current study. Finally, hospital records were collected after the babies in the sample were born to obtain information about pregnancy, delivery, and the newborn weight. 5.3.2. Maternal psychiatric symptoms To assess maternal depressive symptoms 3 months postpartum, the Edinburgh Postnatal Depression Scale (Cox, Holden, & Sagovsky, 1987) was employed. The EPDS, a widely used and sensitive measure of postnatal depression (Cox et al., 1987), consists of 10 items rated from 0 to 3, with higher scores indicative of more depressive symptoms. A continuous total sum score was used in the lack of definitive cut-point for clinical depression in pregnant women (Gibson, McKenzie-McHarg, Shakespeare, Price, & Gray, 2009). The State Anxiety measure of The State and Trait Anxiety Inventory (Spielberger, Gorsuch, Lushene, Vagg, & Jacobs, 1983), a reliable and valid measure of anxiety in both clinical and general population screening, was used to measure anxiety symptoms 3 months postpartum. The State measure of the STAI consists of 20 items rated from 1 to 4, with higher scores indicative of more anxiety symptoms. STAI was used as continuous measure in this study. Both measures showed good internal consistency in the current study (Cronbach’s ␣ for EPDS = 0.81 and for STAI = 0.91). The overall level of depressive and anxiety symptoms was low in this community-based sample (Table 1).

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5.3.3. Mother-infant bonding The Postpartum Bonding Questionnaire (Brockington et al., 2001; Brockington, Fraser, & Wilson, 2006) was used to assess the quality of mother-infant bonding six months postpartum. The Postpartum Bonding Questionnaire was developed to measure bonding and especially problems that could lead to the disruption of mother-infant relationship, and has since been used for research in both clinical (Hairston et al., 2011; Tietz et al., 2014) and non-clinical populations (Moehler et al., 2006; Parfitt et al., 2014). The PBQ consists of 25 items scored on a scale of 0 (“never”) to 5 (“always”), with higher values indicating lower bonding between the parent and the infant. We used a Finnish version of the PBQ, which in this sample demonstrated a Cronbach’s alpha of 0.88 for the total sum score across all items. The PBQ is originally based on four factors, but given the goals of current investigation, only the total score was used. 5.3.4. Infant temperament The Infant Behavior Questionnaire (IBQ), a widely used reliable and valid instrument for assessing infant temperament (Rothbart, 1981, 1986), was used when infants were six months of age to assess their temperament traits. The IBQ is a 94-item questionnaire designed for assessing temperament in children between 3 and 12 months of age (Rothbart, 1981). Parents answer by rating, on a seven-point scale, how often they have observed a particular behavior in their child during the past week. The questionnaire contains six subscales describing different temperament characteristics (see Table 1). Each scale, as follows, demonstrated adequate to good internal consistency in this investigation: Activity level (␣ = 0.79), Fear (0.75), Duration of Orienting (0.77), Smiling and Laughter (0.84), Soothability (0.80) and Distress to Limitations (0.83). Fear and Distress to Limitations reflect infant negative emotionality, while Smiling and Laughter, Duration of Orienting and Soothability are indicative of positive emotionality (Goldsmith & Campos, 1990; Goldsmith & Rothbart, 1999; Kochanska, Coy, Tjebkes, & Husarek, 1998; Komsi et al., 2006). For all scales, higher scores reflect higher levels of the particular temperament characteristic in question. 5.4. Statistical analyses SPSS 20.0 was used to investigate the predictors of early mother infant bonding with standard multiple regression analysis. Because of non-normal distributions, the EPDS, PBQ and STAI scores were transformed with logarithm transformations per recommendations that are frequently made for treating skewed data prior to analysis (Tabachnick & Fidell, 2007). First, we investigated correlations between bonding, mother and father reports of infant temperament, household income, infant gender and maternal age. Next, correlations between mother- and father-reported temperament traits were investigated. To examine predictors of bonding, we used standard multiple regression using infant temperament, maternal depressive and anxiety symptoms and maternal age, infant gender and household income as predictors. As depressive and anxiety symptoms measured by the STAI and the EPDS were highly multicollinear, every model was run separately for the EPDS and STAI scores. In each model, maternal age, infant gender and household income were investigated in the first step of the model. Maternal depressive and anxiety symptoms were added to the second step of the model, and finally, the effect of temperament traits that correlated with bonding were investigated in the third step of the model. Finally, to replicate the findings, we used father-reports of infant temperament in separate models including maternal depressive and anxiety symptoms. 6. Results 6.1. Correlations Higher score of the postnatal bonding questionnaire was positively correlated with maternal depressive (EPDS) and anxiety (STAI) symptoms and infant Distress to Limitations. In turn, mother-infant bonding correlated negatively with infant Smiling and Laughter and infant Soothability. Maternal depressive and anxiety symptoms were strongly related, suggesting common variance between these symptom groups. Maternal depressive symptoms were positively associated with infant Distress to Limitations, while anxiety symptoms were positively associated with infant Duration of Orienting. The background variables did not relate to infant temperament or to bonding with one exception: household income was negatively related to infant maternal report of infant Smiling and Laughter. Correlations between mother-infant bonding, maternal psychiatric symptoms, infant temperament and background variables are presented in Table 2. In terms of father report of infant temperament (Table 3), only infant Distress to Limitations was significantly associated with the quality of mother-infant bonding: higher infant distress was related to lower quality of bonding. There was a trend towards a negative association between bonding and infant Duration of Orienting. Maternal anxiety was positively related to father-reported infant Activity Level and Distress to limitations. Maternal depressive symptoms were not significantly related to father-reported infant temperament, but there was a trend towards a positive correlation between maternal depressive symptoms and infant Distress to Limitations. Mother and father reports of infant Fear (r = 0.396, p = 0.002), Duration of Orienting (r = 0.348, p = 0.007), Smiling and Laughter (r = 0.279, p = 0.032) and Soothability (r = 0.381, p = 0.003) were moderately correlated. Mother and father reports of infant Distress to Limitations were strongly correlated (r = 0.564, p = 0.000). Relations between mother and father reports

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Table 2 Pearson correlations for mother-reported infant temperament at 6 months, depressive and anxiety symptoms at 3 months and mother-infant bonding at 6 months postpartum. Variable

PBQ

AL

F

DuO

SL

So

DL

EPDS

STAI

Activity level (AL) Fear (F) Duration of orienting (DuO) Smiling and laughter (SL) Soothability (So) Distress to limitations (DL) EPDS (Mother) STAI (Mother) Maternal age Infant gender Household income

−0.070 0.169* −0.028 −0.366**** −0.288*** 0.289*** 0.253** 0.260** −0.080 −0.012 0.037

0.034 0.070 0.241** 0.133 0.313*** −0.019 0.030 −0.099 0.122 0.070

0.257*** −0.118 −0.109 0.153 0.108 0.046 −0.057 −0.048 0.108

0.276*** 0.221** −0.052 0.184* 0.234** 0.054 0.092 −0.160

0.434*** 0.029 −0.071 0.008 −0.125 0.166* −0.222**

0.055 −0.157 −0.040 −0.084 0.101 −0.177

0.218** 0.170* 0.006 0.143 0.046

0.699**** 0.096 −0.060 −0.025

0.202* −0.025 −0.084

* ** *** ****

p < 0.10. p < 0.05. p < 0.01. p < 0.001.

Table 3 Pearson correlations for father-reported infant temperament at 6 months, mother-reported depressive and anxiety symptoms at 3 months and motherinfant bonding at 6 months postpartum. Variable

PBQ

AL

F

DuO

SL

So

DL

1. Activity level (AL) 2. Fear (F) 3. Duration of orienting (DuO) 4. Smiling and laughter (SL) 5. Soothability (So) 6. Distress to limitations (DL) 7. EPDS (Mother) 8. STAI (Mother) 9. Maternal age 10. Infant gender 11. Household income

0.094 0.098 −0.165* −0.185 −0.177 0.322** 0.253** 0.260** −0.080 −0.012 0.037

0.090 −0.110 .326** 0.084 0.291** 0.125 .325** −0.200 −0.061 0.143

0.024 0.077 −0.085 0.121 −0.041 0.141 −0.057 −0.166 0.073

0.255** 0.309** −0.197 −0.005 −0.024 −0.037 −0.072 −0.162

0.259** −0.253** 0.092 0.183 −0.083 −0.156 −0.086

−0.313** −0.105 −0.153 −0.307** −0.046 −0.247*

0.241* 0.317** 0.043 0.071 −0.046

* **

p < 0.10. p < 0.05.

of infant Activity Level approached significance (r = 0.242, p = 0.065). These findings suggest that in this sample, mothers and fathers rated infant temperament similarly. 6.2. Standard multiple regression 6.2.1. Multiple regression models for mother-reported temperament The background factors were not found to predict mother-infant bonding. The association between the maternal depressive symptoms and bonding approached significance (␤ = 0.188, p = 0.063) after the infant temperament traits were included in the model (see Table 4). A temperament trait belonging to the dimension of negative emotionality, infant Distress to Limitations, was significantly associated with the quality of mother-infant bond. Infant Smiling and Laughter, a temperament trait reflecting positive emotionality, was negatively associated with the quality of bonding measured by the PBQ, indicating that mothers of children with more smiling experienced better quality of bonding. Models with maternal anxiety symptoms were similar to those described with depressive symptoms (see Table 5). Maternal anxiety predicted mother-infant bonding significantly with maternal age. Infant Smiling and Laughter was negatively and Distress to Limitations positively related to the quality of the bonding measured by the PBQ in similar fashion to the model including maternal depressive symptoms. Maternal age and anxiety symptoms, measured with the STAI, remained significant predictors of bonding even after including temperament traits in the model. 6.2.2. Multiple regression models for father-reported temperament Of the father-reported temperament traits, infant Distress to Limitations was significantly associated with lower motherinfant bonding (␤ = 0.299, p = 0.033; R2  = 0.082, p = 0.033), controlling for maternal depressive symptoms (␤ = 0.294, p = 0.046). When using maternal anxiety symptoms and father-reported infant temperament in the prediction of motherinfant bonding, there was a trend-level finding between bonding and infant Distress to Limitations (␤ = 0.277, p = 0.065) while the previous association of bonding with maternal symptoms of anxiety (␤ = 0.318, p = 0.048) became non-significant (␤ = 0.198, p = 0.236). The background factors in the models with father-reported temperament did not explain variance in bonding.

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Table 4 The predictors of mother-infant bonding: maternal depressive symptoms (EPDS) and mother-reported infant temperament. ␤ Step 1 Maternal age Infant gender Household income

−0.108 0.070 0.133

Step 2 Maternal age Infant gender Household income Maternal depressive symptoms

−0.147 0.089 0.162 0.276*

Step 3 Maternal age Infant gender Household income Maternal depressive symptoms Smiling and laughter Soothability Distress to limitations

−0.170 0.063 0.078 0.188 −0.363** −0.040 0.267**

* ** ***

R2 (adj.)

R2

−0.015

0.020

0.051

0.075

0.224***

0.191***

p < 0.05. p < 0.01. p < 0.001.

Table 5 The predictors of mother-infant bonding: maternal anxiety symptoms (STAI) and mother-reported infant temperament. ␤ Step 1 Maternal age Infant gender Household income

−0.108 0.070 0.133

Step 2 Maternal age Infant gender Household income STAI

−0.249* 0.068 0.205 0.270*

Step 3 Maternal age Infant gender Household income STAI Smiling and laughter Soothability Distress to limitations

−0.238* 0.059 0.103 0.227* −0.375** −0.083 0.259**

* ** ***

R2 (adj.)

R2

−0.015

0.020

0.060

0.103

0.319***

0.217***

p < 0.05. p < 0.01. p < 0.001.

7. Discussion In the present study, we examined associations between maternal psychiatric symptoms, infant temperament and mother-infant bonding six months postpartum. In line with earlier research, we found that maternal depressive symptoms predicted mother-infant bonding problems. Additionally, we found that maternal anxiety symptoms predicted motherinfant bonding problems, which adds to this literature given that depressive symptoms are often the focus of investigation (Edhborg et al., 2011; Tietz et al., 2014). Most central to our goals, we found that infant temperament traits were associated with mother-infant bonding: mother-reported infant positive emotionality, measured by the subscale Smiling and Laughter, was negatively correlated with PBQ, which is indicative of better maternal bonding. In turn, mother-reported infant negative emotionality, measured using subscale of Distress to Limitations was related to higher PBQ scores, indicating lower quality of bonding at six months postpartum. Furthermore, father-reported infant Distress to Limitations was associated with lower quality of mother-infant bonding at six months postpartum. To our knowledge, this is the first study that identifies independent associations between different aspects of infant negative and positive affectivity and early bonding. Our findings suggest that infant characteristics, after taking into account the effects of maternal symptoms of depression and anxiety, are associated with mother-infant bonding. Infant distress, which is a marker of negative emotional reactivity, seems to be central to maternal impressions of bonding, as both mother- and father-reported infant Distress to Limitations

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were significant correlates of bonding. This finding likely reflects the dynamic nature of early parent-child relationships: a baby that is irritable and not easily satisfied, or that infrequently smiles, provides mothers fewer opportunities for reinforcing, enjoyable interactions that may enhance early bonding. In contrast, a less easily distressed baby that more readily displays clear signals of positive affect (e.g., smiling) is experienced as being easier for parent (Kochanska et al., 2004). Indeed, such interactions and maternal impressions about the mother-infant relationship are important in the development of positive parent-child interactions, which have proved to be central to children’s healthy development (Milgrom et al., 2004). Moreover, infant tendency towards negative affect might act as an indicator of infant sensitivity to a non-optimal environment (Belsky, Kuang-Hua, & Crnic, 1998; Belsky & Pluess, 2012; Kim & Kochanska, 2012; Pluess & Belsky, 2010; van Aken, Junger, Verhoeven, van Aken, & Dekovic, 2007) and in many cases, infant and parent characteristics interact to contribute to either positive or negative patterns of behavior (Atzaba-Poria, Deater-Deckard, & Bell, 2014; Clark, Kochanska, & Ready, 2000). As such, our findings underline the importance of considering infant and parent characteristics together when examining potential mechanisms that influence the early developing parent-infant relationship. While not the primary goal of our research, as might be anticipated based on the previous work, we also found that maternal self-reported depressive symptoms were significantly associated with infant Distress to Limitations. A similar trend for the relation between father-reported infant distress and maternal depressive symptoms was also identified, with this trend level, as opposed to significant, relation likely attributable to lower power given the small sample of fathers. In line with earlier research, this indicates that depressive symptoms of mothers may affect their interaction with their infant, which may increase infant negative emotionality (Bridgett et al., 2009). Although the mechanisms of such relations were not considered in the current investigation, in line with prior investigations, parenting and/or shared genetic influences (likely both) are potential mechanisms that may explain the relation between maternal depressive symptoms and infant negative emotionality. These possibilities, as well as others, should be directly considered in future work. Another possibility is that maternal depression contributes to bias in mothers reporting of their children’s negative emotionality (See Gartstein, Bridgett, Dishion, & Kaufman, 2009 for discussion of the depression-distortion hypothesis). However, the trend level relation between maternal depressive symptoms and father-reported infant distress provides more confidence that this potential mechanism (i.e., maternal reporting bias) does not explain the findings in the current study. A more nuanced pattern of relations was observed between maternal symptoms of anxiety and mother and father reports of infant temperament. Mother-reported anxiety was related to mother-reported infant Duration of Orienting and to fatherreported infant Activity Level and Distress to Limitations. In other words, when mothers reported more symptoms of anxiety, fathers reported infants being more active and irritable, which is somewhat consistent with findings in the current investigation wherein maternal depressive symptoms were observed to be related to mother and father-reported Distress to Limitations (Bridgett et al., 2009; Hanington et al., 2010). On the other hand, mothers with postnatal anxiety symptoms saw their infants as orienting longer to stimuli in a variety of contexts. To our knowledge, prior studies have not considered such relations, although a few have reported that prenatal stress, not considered in this investigation, was associated with longer duration of orienting (Lin, Crnic, Luecken, & Gonzales, 2014) making it difficult to speculate as to the potential mechanisms that might be considered in future work. That said, although longer duration of orienting may convey benefits to later developmental and social-emotional outcomes (Bridgett et al., 2011; Kochanska, Murray, & Harlan, 2000), it also seems possible that longer duration of orienting in infants of mothers who experience more anxiety symptoms may reflect a very early manifestation of attentional bias that has been identified as a mechanism in the emergence of clinical manifestations of anxiety (see Bar-Haim, Lamy, Pergamin, Baktermans-Kranenburg, & van IJzendoorn, 2007 for discussion), inefficient attention shifting potentially harmful for emotion regulation (Calkins & Johnson, 1998; Rothbart, Ziaie, & O’Boyle, 1992) or slower habituation to novel stimuli. In addition to replication of relations between maternal anxiety symptoms and infant duration of orienting, potential explanations for such relations, such as those noted here, should also be considered in future studies. In our data, mother and father reports of temperament were moderately to strongly associated, which is in line with earlier studies of such relations (Burney & Leerkes, 2010; Gartstein & Rothbart, 2003; Parade & Leerkes, 2008; Putnam, Helbig, Gartstein, Rothbart, & Leerkes, 2014). Reports of infant distress produced the strongest significant correlation between parents (see also Goldsmith & Campos, 1990), while the association between parents’ reports of infant Activity Level was moderate, but only near-significant, which is potentially attributable to the smaller sample available for examination of these relations. Thus, while examination of relations between mother and father reports of infant temperament was not a primary goal of the current investigation, our findings add to this literature. Despite the moderately strong convergence of parent reports of temperament, more mother-reported infant temperament traits were associated with bonding in regression analyses compared to father-reported infant temperament characteristics. Of father-reported infant temperament traits, only infant distress was related to mother-infant bonding in regression analyses. One possible explanation for this finding is the salience of infant negative reactivity to both parents when compared to more nuanced infant temperament attributes, reflected in behaviors related to attention or fearfulness. However, the correlations of both parent reports of infant smiling and soothability with mother-infant bonding were similar in size and direction, yet non-significant or at trend levels for father reports. Thus, it also seems plausible that our smaller sample of fathers limited the power to detect significant, albeit more modest, relations between other father reported infant temperament attributes and mother-infant bonding. Our findings also have several clinical implications. First, our findings point to the importance of considering infant temperament attributes, particularly distress (i.e., anger/frustration) as well as maternal well-being in assessments of mother-infant bonding, and in assessments of factors potentially contributing to bonding difficulties. Second, clinicians

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should be aware of parent-reported infant positive emotionality as a component of more optimal mother-infant relationships, and potentially work with parents to help them identify positive emotional signals they may receive from their infants. Next, our study suggests that anxiety symptoms might be a risk factor for lower quality mother-infant bonding. Thus, anxiety, along with postpartum depression, should be considered in clinical settings. Finally, education about infant temperament traits should be used more in the treatment and counseling of parents both in child health care and in special health care settings. The knowledge about temperament can be used in identifying the aetiology of infant irritability, informing parents about the individual differences between infants and giving instructions in handling of infants with different temperament traits. 7.1. Strengths and limitations There are several strengths and limitations to our approach in the current investigation that should be acknowledge, and in the latter case, potentially improved upon in future studies. Two of the main strengths of the current investigation were the use of a longitudinal design and our consideration of both mother and father ratings of infant temperament. In regards to our use of mother and father reported infant temperament, limitations inherent in relying upon a single source of measurement were minimized. In addition to these strengths, data was gathered as a part of larger new birth cohort study using validated measures. Despite the strengths of our approach, several limitations should be addressed in future studies. For example, our sample size was modest, especially concerning fathers. As we noted earlier, this may have affected power to detect meaningful effects, and in some cases, might have minimized convergence of findings across mother and father reports of temperament in relation to mother-infant bonding. Along related lines, attrition was somewhat higher than anticipated, which might have affected our findings. However, few differences emerged between mothers and fathers who did not complete all of the measures and those that did. Indeed, in the case of fathers, no differences were identified between fathers who dropped out compared to those who remained in the study. Although attrition is never ideal, these findings bolster confidence that our findings were minimally affected, if at all, by attrition in the current investigation. Next, there are both pros and potential cons to our use of parental reports of mother psychiatric symptoms, infant temperament and mother-infant bonding. Self-reports of psychiatric symptoms are widely used in research and clinical settings, and often converge with clinical interviews. Similarly, parent reports of infant temperament have demonstrated anticipated relations with corresponding laboratory measures (Goldsmith & Rothbart, 1991; Kochanska, Murray, & Coy, 1997), and can provide important information that might not be observed during laboratory visits (Gartstein & Marmion, 2008; Rothbart, 1981). Moreover, parent perception of infant temperament could arguably be of more relevance than laboratory assessments to understanding the role of children’s temperament in contributing to parent-infant bonding difficulties. Nevertheless, it also is possible that parent reports may be biased (Rothbart & Bates, 1998; Rothbart & Goldsmith, 1985). Although we included both mother- and father-reports of temperament, minimizing in some regards the potential disadvantages of relying only upon maternal report for all measures, future investigators should consider using laboratory measures of infant temperament. Indeed, given the importance of doing so, ongoing data collection in the context of the larger FinnBrain Birth Cohort Study is utilizing laboratory assessments of infant temperament attributes to potentially replicate findings from the current investigation. Finally, mother-reported problems in bonding as well as depressive and anxiety symptoms were low, indicating few clinically significant bonding difficulties in our sample Along similar lines, given our use of a non-clinical, community sample, we used self-reports of depressive and anxiety symptoms instead of clinical diagnoses ascertained via a clinical interview in this study. As such, despite good convergence between self-reports of the depressive and anxiety symptom measures used in the current study and findings based upon structured clinical interviews, it remains a possibility that our findings may not generalize to clinical samples. To address these limitations, future work may want consider clinical samples, such as new mothers diagnosed with anxiety and/or depression, alone or in comparison to controls, in examining the potential contribution infant temperament makes to bonding difficulties mothers may experience in the first year postpartum. 8. Conclusion Our study provides new, more specific evidence (e.g., by considering fine-grained aspects of infant temperament) of relations between infant temperament attributes and mother-infant bonding difficulties in the first year postpartum. 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