X. MARITAL AND EMOTIONAL ADJUSTMENT IN MOTHERS AND INFANT SLEEP ARRANGEMENTS DURING THE FIRST SIX MONTHS Douglas M.Teti, Brian Crosby, Brandon T. McDaniel, Mina Shimizu, and Corey J.Whitesell ABSTRACT Although parents’ structuring of infant sleep is complexly determined, little attention has been given to parents’ marital and personal adjustment in shaping sleep arrangement choices. Linkages were examined between infant sleep arrangements at 1 and 6 months and mothers’ marital adjustment, co-parenting quality, and depressive symptoms. The final study sample was composed of 149 families (53% girl infants, 86% European American). Bed sharing mothers had lower co-parenting quality, and, at 6 months, more depressive symptoms than mothers of infants in solitary sleep. One-month co-parenting quality was associated with predictable shifts in sleep arrangements from 1 to 6 months, but 1-month sleep arrangements did not predict changes in personal or co-parenting quality. Findings emphasize the need for greater attention to marital and emotional health in influencing family-level decisions about infant sleep arrangements.

One of the biggest controversies in pediatric sleep involves parental choices about where their infants sleep. These choices are complexly determined, informed by a host of medical, cultural, and personal considerations (McKenna & Volpe, 2007; Mindell, Sadeh, Kohyama, & How, 2010). We believe an important ingredient has been left out of this conversation, namely the roles played by parents’ marital and emotional health in shaping sleep arrangement choices. Our interest in this is based on several interrelated lines of evidence. First, parents in Western cultures who co-sleep (i.e., share the same room or the same bed with their infants) are less satisfied with their choice of sleep arrangements, more maritally distressed, and report more depressive symptoms than parents whose infants sleep in separate

Corresponding author: Douglas M. Teti, Human Development and Family Studies, The Pennsylvania State University, S-211 Henderson Bldg., University Park, PA 16802, email: [email protected] This study was supported by a grant from a grant from the National Institute of Child Health and Human Development (R01HD052809), awarded to the first author.

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rooms (Dollberg, Shalev, & Chen, 2010; Germo, Chang, Keller, & Goldberg, 2007), although Germo et al. (2007) found these associations to be limited primarily to parents in reactive co-sleeping arrangements (i.e., children who returned to their parents’ room or bed after an extended period of solitary sleep). Other work, however, found linkages between co-sleeping and parental distress about their infants’ sleep even when parents strongly endorsed their choice to co-sleep with their infants (Countermine & Teti, 2010), rendering unclear whether one’s level of support for co-sleeping moderates these associations. In each of these studies, it was implied that parents’ distress was in response to, rather than a determinant of, sleep arrangement choices and infant sleep problems. Causal influences between parental depressive symptoms, marital distress, and infant sleep arrangements, however, were not specifically addressed. Second, there is a well-established relation between elevated depressive symptoms in mothers and infant night waking (Armitage et al., 2009; GressSmith, Luecken, Lemery-Chafant, & Howe, 2011). The nature of this link is not clear. Maternal dysphoria may be the result of chronic infant night waking, mediated by cumulative maternal sleep loss that comes as a consequence of coping with an infant who does not sleep well (McDaniel & Teti, 2012). Other work, however, implicates maternal depression as causal to infant night waking via biologically based mechanisms (Armitage et al., 2009) or by implied albeit unspecified maternal behaviors (Gress-Smith et al., 2011). None of these studies specifically examined behavioral mechanisms, such as parents’ choices about infant sleep arrangements or parental behavior in mediating linkages between parental distress and infant night waking. Evidence suggests that behaviorally based mechanisms should be considered. Teti and Crosby (2012) found that mothers with elevated depressive symptoms were more likely to seek out and spend more time with their infants at night (i.e., bed share) than mothers with low depressive symptoms, which in turn appeared to disrupt infant sleep. Such tendencies were not necessarily associated with infant distress. Although Teti and Crosby (2012) emphasized bidirectional influences, they found more support for a motherdriven model of influence, in which maternal depressive symptoms predicted infant night waking via maternal presence with and waking infants at night, than for infant-driven models in which maternal depressive symptoms and excessive worry were predicted by infant night waking. They suggested that distressed mothers may be more likely to spend time with their infants at night, compared to nondistressed mothers, to satisfy unmet emotional needs or because of unrealistic worries about infant safety. Such activities, however, may influence infants’ sleep quality. These results support Tikotzky and Sadeh’s (Tikotzky and Sadeh, 2009) findings that mothers’ distress to infant night waking predicted maternal attempts to soothe infants at night, which in turn predicted infant night waking. They are also consistent with the premise 161

that parental personality, cognition, and behavior influence infant sleep, and that linkages between infant sleep and nighttime parenting are dynamic and bidirectional (Sadeh, Tikotzky, & Scher, 2010). Limitations of Teti and Crosby’s (Teti and Crosby, 2012) study included its cross-sectional design, precluding meaningful analyses of potential causal influences, and the absence of measures of maternal functioning, such as marital adjustment and co-parenting quality, which may figure importantly in understanding parental choices about sleep arrangements (Germo et al., 2007). In the present study, we examined both contemporaneous and longitudinal associations between mothers’ personal, marital, and co-parenting distress and infant sleep arrangements from 1 to 6 months of infant age. The choice to assess stability and change across this time period was because of prior work indicating that, whereas U.S. parents appear to be more open to experimenting with a variety of sleeping arrangement options early in the postpartum period, they have largely settled on a particular sleeping arrangement by the time their infants are 6 months of age (Hauck, Signore, Fein, & Raju, 2008). We thus did not include the 3 months data collection point in this study, because of concerns that, by that age, parents would not have yet made a stable sleep arrangement choice. Of particular interest was whether sleep arrangement choices at 1 month predicted changes in mothers’ marital, co-parenting, and personal adjustment from 1 to 6 months (as implied in earlier work), and/or whether mothers’ marital, co-parenting, and personal adjustment at 1 month predicted changes in room and/or bed sharing from 1 to 6 months. It is possible, for example, that mothers in more distressed marriages or with high levels of personal distress at 1 month may be more likely over time to choose infant sleep arrangements that enable them to spend more time with their infants at night, compared to mothers in more supportive marital and coparenting relationships or who are less personally distressed. Because of its focus on parenting in infant sleep contexts, the present study fits well within the immediate context level in the systems perspective model presented in Figure 1 (El-Sheikh & Sadeh, Chapter I, in this volume). In addition, because we frame and discuss our findings in relation to the U.S. cultural norms regarding infant sleep arrangements, we believe the present study fits within the broader cultural context level of the systems perspective model in Figure 1 (Chapter I, in this volume). Aims and Hypotheses

We examined how infant sleeping arrangement choices change from 1 to 6 months of age, and the degree to which mothers endorse their infants’ current sleep arrangement. Although solitary sleep is normative for U.S. infants (Mindell et al., 2010), prior work suggests that many U.S. parents do not consistently use solitary sleep, or use it at all, during the first six months 162

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of life, switching in and out of alternative sleep arrangements as their infants’ sleep consolidates across the first six months of life (McCoy et al., 2004). We hypothesized that the highest proportion of room and bed sharing would occur when the infant was 1 month old (McCoy et al., 2004), when infant nighttime feeding demands are greatest. Further, we expected that from 1 to 6 months, room and bed sharing would decrease, and solitary sleep would increase, but that there would still be some parents room sharing and bed sharing with their 6-month-old infants. In light of U.S. norms supporting solitary sleep, we hypothesized that mothers would be more likely to endorse (i.e., strongly prefer) solitary sleeping arrangements over nonsolitary sleeping arrangements. Another study aim was to assess the concurrent and longitudinal associations between maternal depressive symptoms, marital adjustment, coparenting quality, and infant sleep arrangements at and across 1 and 6 months of age. If longitudinal linkages exist, is there stronger statistical support for paths linking earlier sleep arrangement choices with later maternal distress, or for pathways linking earlier maternal distress to later sleep arrangement choices? This question was considered exploratory.

METHOD Participants

One hundred sixty-seven families and their 1-month-old healthy infants were recruited into a larger, ongoing longitudinal NICHD-funded study (SIESTA—Study of Infants’ Emergent Sleep Trajectories). Mothers were approached in two local hospitals in central Pennsylvania within 24–48 hr after delivery by project staff, who described the study and provided a flyer with contact information. Interested mothers were called at home 2–3 weeks after infant discharge, and an initial home visit was scheduled when infants were 4 to 6 weeks of age. Of the 167 families recruited, 12 withdrew from the study between 1 and 6 months of infant age. These 12 dropouts were compared with the 155 participants who remained in the study on all study variables at 1 month, using one-way analysis of variance (ANOVA), chi-square, and Fisher Exact Probability tests. Included in these analyses were infant gender, maternal education, ethnicity, maternal age, marital status, family income, whether families used public assistance, family size, employment status, number of hours employed per week, and whether infants were in daycare or being breastfed. No differences were found between dropouts and completers on any of these variables, nor on maternal depressive symptoms, marital adjustment, co-parenting quality, and infant bed sharing arrangements. 163

Six additional families did not provide complete data on infant sleep arrangements, and thus the final analysis sample consisted of 149 families who had complete data on sleeping arrangements from 1 through 6 months of infant age. Of these, 143 were two-parent families. Infants’ (53% girls) mean age at the 1 and 6 month visits was 1.22 months (SD ¼ 0.16) and 6.14 months (SD ¼ 0.41), respectively. Mothers ranged in age from 18–43 years (M ¼ 29.42, SD ¼ 5.35) and 86% of the sample was European American, with the remaining 14% African American, Asian, Latino, or “Other.” Median family income was $65,000/year. Approximately 99% of the mothers had completed high school, 61% had at least a bachelor’s degree, and 32% had completed a post-baccalaureate degree (master’s degree or higher). Procedures

All families were participating in a larger study of parenting and infant sleep, involving home visits when infants were 1, 3, 6, 9, 12, 18, and 24 months of age. In the present study, we focus on the 1- and 6-month visits, on which all data collection is complete. At each visit, mothers were asked to complete a variety of questionnaire measures pertaining to their infants’ sleep arrangements, parental depressive symptoms, marital adjustment, and co-parenting quality. Measures Infant Sleep Arrangements and Maternal Preference for Sleep Arrangement

The Sleep Practices Questionnaire (SPQ) (Goldberg & Keller, 2007), a measure of parental perceptions about their infants’ sleep behavior, obtained information about infant sleep arrangements and the degree to which the current infant sleep arrangement was preferred. Mothers completed the SPQ at both the 1 and 6 month age points. From the SPQ, parental responses were scored to the question, “Where does your baby usually sleep at night?” Four sleep arrangement categories were scored: Solitary sleep (infant slept in a separate room), room sharing (infant slept in the same room as parents, but on a separate sleeping surface), bed sharing (infant slept in the same bed as the parents), and combination (infant’s sleep arrangement varied across the night). Mothers’ responses to the question, “Is your baby’s current sleep location the place that you most prefer for him/her to sleep?” were used to determine the preference for infant sleep arrangements (“No, not my preference,” “Yes, to some extent my preference,” and “Yes, definitely my preference.”). Maternal Depressive Symptoms

The depression subscale of the Symptoms Checklist-90, Revised (SCL-90-R) (Derogatis, 1994) assessed depressive symptoms in mothers when infants were 1-month and 6-months old. The depression subscale consists of 13 items (e.g., 164

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“worrying too much about things”), and possesses strong construct and criterion validity and test-retest reliability (Derogatis, 1994). In the present study, as ¼ .90 at 1 and 6 months. Marital Adjustment

When infants were 1 month old, mothers with live-in partners completed the Locke-Wallace Marital Adjustment Test (MAT) (Locke & Wallace, 1959) with four additional items (religious matters; aims, goals, and things believed to be important; making major decisions; and household tasks) incorporated from Spanier’s (Spanier, 1976) Dyadic Adjustment Scale (DAS). The MAT and DAS are well-established measures and have strong psychometric credentials (Haque & Davenport, 2009). In this study, the modified MAT a ¼ .80. Quality of Co-Parenting

The Co-Parenting Relationship Scale (CRS) was obtained from mothers with live-in partners at 1 and 6 months, and has adequate internal and testretest reliability and construct validity (Feinberg, Brown & Kan, 2012). The CRS was specific to mothers’ perceptions of how well she and her partner worked together as a child-rearing team. The CRS taps parental perceptions of inter-parental agreement, closeness, exposure of child to conflict, coparenting support, undermining, endorsement of partner’s parenting, and division of labor. In this study, positive co-parenting dimensions (agreement, closeness, support, endorsement, and division of labor) were significantly inter-correlated at all age points (rs ¼ .27 to .81, ps < .001). These five dimensions were combined by summing their scores to create positive coparenting composites at 1 (a ¼ .83) and 6 months (a ¼ .82). The two dimensions of negative co-parenting (competition-undermining and exposure to conflict) were also significantly inter-correlated at 1 and 6 months (rs ¼ .31 and .49, ps < .01), and were summed to create a negative coparenting composite at each age point. Plan of Analysis

Research questions were addressed using correlation, analysis of variance, covariance, and chi-square. Missing data from 1 to 6 months was minimal, and thus no imputation missing data replacement analyses were conducted.

RESULTS Preliminary Analyses

One-way ANOVAs and chi-square analyses were conducted to examine relations between sociodemographic variables (ethnicity, education, income, 165

partner status, maternal age, parity, and breastfeeding status), and infant sleep arrangements at 1 and 6 months. Sociodemographics were not associated with infant sleep arrangements at 1 month. However, mothers’ ethnicity (European American vs. other) [x2 (3) ¼ 21.84, p < .001, phi ¼ .38], partner status (yes, no) [x2 (3) ¼ 10.38, p ¼ .02, phi ¼ .26], and whether mothers were breastfeeding [x2 (3) ¼ 9.87, p ¼ .03, phi ¼ .25] were associated with 6-month sleep arrangements. European Americans were more likely than minority families to use solitary sleep arrangements (71% vs. 43%) and less likely to bed share (4% vs. 33%); the two groups did not differ in their use of room sharing (13% vs. 10%) and combination sleep arrangements (12% vs. 14%). In comparison to single-parent families, two-parent families were more likely to use solitary sleep arrangements (70% vs. 30%), less likely to either room share (11% vs. 40%), or bed share (7% vs. 20%) with no differences in the use of combination sleep arrangements (12% vs. 10%). Finally, compared to non-breastfeeding mothers, breastfeeding mothers were more likely to bed share (11% vs. 3%) or to use combination sleep arrangements (14% vs. 7%). About equal percentages of breastfeeding and non-breastfeeding mothers used solitary sleep arrangements (67% vs. 68%), and breastfeeding mothers were less likely to room share with their infants than non-breast-feeding mothers (8% vs. 22%). Mean values for mothers’ depressive symptoms (1 month M ¼ 7.90, SD ¼ 7.56; 6 months M ¼ 6.45, SD ¼ 6.83) were lower than the clinical cutoff value of 13 (Derogatis, 1994). Thus, the majority of mothers in the present study were not highly distressed, although mothers’ depressive symptoms scores ranged from 0–38 at 1 month and 0–40 at 6 months (widest possible range ¼ 0–52). Mothers’ marital adjustment (1 month M ¼ 134.31, SD ¼ 22.79), positive co-parenting (1 month M ¼ 143.48, SD ¼ 22.49; 6 months M ¼ 145.16, SD ¼ 19.53), and negative co-parenting (1 month M ¼ 17.74, SD ¼ 6.20; 6 months M ¼ 17.07, SD ¼ 6.29) also suggested that most mothers in this sample were not experiencing high levels of marital distress. Nevertheless, marital adjustment scores (29–171, widest possible range ¼ 2–178), positive co-parenting (33–183 at 1 month; 85–188 at 6 months; widest possible range ¼ 24–168), and negative co-parenting (11–40 at 1 month; 11–50 at 6 months; widest possible range ¼ 11–77) ranged widely. Table 1 presents correlations (Pearson rs) between mothers’ reports of marital adjustment, co-parenting, and depressive symptoms. As expected, positive contemporaneous associations were found between mothers’ marital adjustment and positive co-parenting at 1 and at 6 months, and between maternal depressive symptoms and negative co-parenting at 1 and at 6 months. In addition, contemporaneous negative associations were found between mothers’ depressive symptoms and marital adjustment and positive co-parenting at 1 month, and between depressive symptoms and positive coparenting at 6 months. Positive and negative co-parenting were negatively 166

MATERNAL DISTRESS & INFANT SLEEP ARRANGEMENTS

TABLE 1 INTERCORRELATIONS BETWEEN MOTHERS’ MARITAL ADJUSTMENT, DEPRESSIVE SYMPTOMS, AND POSITIVE AND NEGATIVE CO-PARENTING AT 1 AND 6 MONTHS Marital Adjustmenta

Depressive Symptoms

Positive Co-Parenting

Negative Co-Parenting

– – – –

.39 (142) – .52 (143) .42 (143)

.72 (142) .27 (143) – .64 (143)

.54 (142) .22 (143) .50 (144) –

Marital adjustmenta Depressive symptoms Positive co-parenting Negative co-parenting

Note. Associations reported above the diagonal for 1-month assessment and below the diagonal for 6-month assessment. Number in parenthesis refers to sample size for each analysis. a Marital adjustment assessed at 1-month only.  p < .01.  p < .001.

associated at 1 and 6 months. There was also strong cross-time stability, from 1 to 6 months, in maternal depressive symptoms, r(147) ¼ .51, p < .001, positive co-parenting, r(140) ¼ .76, p < .001, and negative co-parenting, r(140) ¼ .58, p < .001. Stability of Infant Sleep Arrangements From 1 to 6 Months, and the Degree of Mothers' Endorsement of Their Sleep Arrangement Choices

At 1 month (Table 2), 27% of infants slept in a separate room (solitary sleep), whereas 48% and 11%, respectively, slept in the same room (room sharing) or in the same bed as parents (bed sharing). Sleep arrangements for the remaining 13% involved some combination of the above in a given night. By 6 months (Table 2), however, two-thirds (67%) of infants slept in a separate

TABLE 2 CROSSTABULATION

OF INFANT

SLEEP

SLEEP ARRANGEMENTS, NUMBER, AND PERCENTAGE ARRANGEMENT AT 1 AND 6 MONTHS-OF-AGE

OF INFANTS BY

6-month 1-month Solitary Room share Bed share Combination Totals

Solitary

Room Share

Bed Share

Combination

39 47 4 10 100 (67.1%)

0 13 1 5 19 (12.8%)

0 4 7 1 12 (8.0%)

1 8 5 4 18 (12.1%)

Totals 40 72 17 20

(26.9%) (48.3%) (11.4%) (13.4%) 149

Note. x2 ¼ 56.42, p < .001, phi ¼ .62. Bolded values indicate stable sleep arrangements over time. “Combination” consisted of separate room/same room (1-month n ¼ 2, 6-month n ¼ 1); separate room/ parents’ bed (1-month n ¼ 6, 6-month n ¼ 10); same room/parents’ bed (1-month n ¼ 12, 6-month n ¼ 7).

167

room, with about 13% room sharing, 8% bed sharing, and 12% engaged in combination sleep. There was significant stability in sleep arrangements across age, x2 (9) ¼ 56.42, p < .001, kappa ¼ .21, although this was carried primarily by solitary sleepers (98%) and bed sharers (41%) (see Table 2). Chi-square analyses conducted at both 1 and 6 months indicated a strong association between sleep arrangements and mothers’ preferences for their sleep arrangement choices, 1 month x2 (6) ¼ 42.07, p < .001, phi ¼ .53; 6 month x2 (6) ¼ 60.42, p < .001, phi ¼ .64. Ninety-five percent and 91% of mothers of infants in solitary sleeping arrangements at 1 and 6 months, respectively, strongly endorsed their choice (“definitely my preference”). By contrast, at 1 and 6 months, 64% and 53% of room sharing mothers, 35% and 42% of bed sharing mothers, and 20% and 17% of mothers in combination sleeping arrangements strongly endorsed their choice. Additional chi-square analyses revealed that mothers’ preferences for sleep arrangement choices at 1 and 6 months were not related to mothers’ ethnicity, maternal parity (one child vs. multiple children), marital status, and breastfeeding status. Correlations revealed no associations between mothers’ preference for sleep arrangements and infants’ age, maternal education, and income. Concurrent Links Between Maternal Depressive Symptoms, Marital Adjustment, Co-Parenting Quality, and Sleep Arrangements At 1 Month-of-Age

One-way ANOVAs, followed by Student Newman–Keuls (SNK) pairwise comparisons, were conducted to examine concurrent associations between 1-month sleep arrangements and mothers’ 1-month marital adjustment, positive and negative co-parenting, and depressive symptoms. These analyses did not include all 149 mothers because some had missing data on the dependent variables under analysis. For example, analyses involving marital adjustment and co-parenting measures did not include mothers who were not living with a partner. Table 3a presents the group means and standard deviations for these analyses. Significant main effects of 1 month sleep arrangements were obtained only for negative co-parenting, F(3, 140) ¼ 2.70, p ¼ .048, partial h2 ¼ 5.47%. Post-hoc pairwise comparisons revealed that mothers who bed shared with infants had significantly higher negative coparenting scores (i.e., more undermining-competition and exposure to conflict) than mothers whose infants slept in separate rooms (p < .05). No other comparisons were significant. At 6 Months-of-Age

Similar analyses were conducted at 6 months (marital adjustment was not assessed at 6 months) (see Table 3b). For positive and negative co-parenting, these analyses were conducted on a slightly smaller number of mothers than 168

MATERNAL DISTRESS & INFANT SLEEP ARRANGEMENTS

TABLE 3 INFANT SLEEP ARRANGEMENTS AND MATERNAL CHARACTERISTICS AT

1

AND

6

MONTHS-OF-AGE

a. Infant Sleep Arrangements at 1 Month-of-age and Maternal Characteristics Solitary Marital adjustment n Positive co-parenting n Negative co-parenting n Depressive symptoms n

a

141.18 39 149.61a 39 15.88a 39 7.59a 39

(15.27) (16.61) (4.89) (7.49)

Room Share a

133.09 (22.90) 69 142.74a (24.31) 70 17.93ab (6.29) 70 7.72a (7.27) 72

Bed Share a

125.53 (31.49) 17 143.24a (24.77) 17 20.81b (8.08) 17 7.94a (6.96) 17

Combination 132.39a (24.32) 18 132.75a (21.40) 18 18.17ab (5.49) 18 9.50a (9.43) 20

b. Infant Sleep Arrangements at 6 Months-of-Age and Maternal Characteristics

Positive co-parenting n¼ Negative co-parenting n¼ Depressive symptoms n¼

Solitary

Room Share

Bed Share

Combination

148.01a (17.43) 98 16.22a (5.41) 98 5.20a (4.88) 100

140.11ab (16.75) 16 17.30a (4.33) 16 8.26 ab (10.08) 19

130.07b (19.78) 11 20.18a (8.66) 11 12.58b (8.51) 12

143.41ab (27.47) 18 19.54a (9.25) 18 7.72ab (8.51) 18

Note. Numbers in parentheses are standard deviations. Means in each row with different superscripts are significantly different from each other, p < .05, Student Newman–Keuls procedure. Marital adjustment assessed at 1-month only.

the full 149 because of missing data. Significant main effects of 6-month sleep arrangements, with effect sizes of moderate magnitude, were obtained for positive co-parenting, F(3, 139) ¼ 3.64, p ¼ .01, partial h2 ¼ 7%, and depressive symptoms, F(3, 145) ¼ 5.60, p ¼ .001, partial h2 ¼ 10%, and the sleep arrangement main effect was non-significant for negative co-parenting, F(3, 139) ¼ 2.62, p ¼ .05. Post-hoc pairwise comparisons revealed that mothers’ positive co-parenting was lower among bed sharing mothers at 6 months, compared with mothers whose infants slept in separate rooms (p < .05). In addition, bed sharing mothers reported higher levels of depressive symptoms than mothers whose infants slept in separate rooms, p < .05. These results did not change when ethnicity, partner status, and whether or not mothers were breast-feeding at 6 months were statistically controlled. Longitudinal Links Between Maternal Depressive Symptoms, Marital Adjustment, Co-Parenting Quality, and Sleep Arrangements

Sleep arrangement X Infant age ANOVAs were conducted separately on positive co-parenting, negative co-parenting, and maternal depressive 169

symptoms to assess whether sleep arrangement decisions at 1 month-of-age predicted change in mothers’ co-parenting quality and personal distress from 1 to 6 months-of-age. The statistical “effect” of interest in these analyses was the Sleep arrangement X Infant age interaction, which if significant would indicate that change across age in a specific index differed for different sleep arrangement subgroups. In none of these analyses was this interaction significant, nor were there any statistically significant effects obtained for infant age. Additional analyses were then conducted to assess whether change in sleep arrangements across waves was predicted by mothers’ marital adjustment, quality of co-parenting, and depressive symptoms at 1 month (see Table 4). Sleep arrangement change groups were created, based on the patterns of continuity and change across age (see Table 2), with the provison that each change group’s sample size was at least five. These groups include stable solitary (n ¼ 38), stable room sharing (n ¼ 13), stable bed sharing (n ¼ 7), change from non-solitary to solitary (n ¼ 61), change from non-bed sharing to bed sharing (n ¼ 5), and change from non-combination to combination (n ¼ 14). These change groups accounted foSr 138 of the 149 participants in the full sample. One-way ANOVAs and chi-square analyses revealed that change groups were unrelated to all sociodemographic variables with one exception: TABLE 4 MEANS AND STANDARD DEVIATIONS OF STABILITY AND CHANGE IN INFANT SLEEP ARRANGEMENTS FROM 1 TO 6 MONTHS-OF-AGE AND MOTHERS’ MARITAL, CO-PARENTING, AND EMOTIONAL ADJUSTMENT ASSESSED WHEN THE INFANT WAS 1 MONTH OLD

Assessments at 1-Month Marital adjustment n Positive co-parenting n Negative co-parenting n Depressive symptoms n

Stable Solitary/ Non-Solitary to solitary

Stable Room Share

Stable Bed Share

Non-Bed Sharing to Bed Sharing

Non-Combination to Combination

137.72a (20.49) 98 146.70a (20.11) 99 16.49a (5.03) 99 7.41a (7.13) 99

130.17a (10.51) 12 135.11a (23.12) 11 18.48a (6.60) 11 7.04a (7.23) 13

120.14a (33.71) 7 118.90b (24.99) 7 25.50b (8.70) 7 8.86a (9.37) 7

120.80a (10.33) 5 145.17a (14.87) 5 19.96a (5.93) 5 8.20a (5.50) 5

125.00a (38.67) 13 140.23a (29.48) 14 18.93a (8.52) 14 8.29a (6.92) 14

Note. Numbers in parentheses are standard deviations. Different superscripts denote significant differences (ps < .05) between the stable solitary/non-solitary to solitary group and each of the remaining sleep arrangement change groups, using a priori, planned comparison.

170

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mothers’ ethnicity, x2(5) ¼ 28.32, p < .001, phi ¼ .45. Minority families were more likely than European Americans to fall into the stable bed sharing group (6% vs. 3%), less likely than European Americans to move infants from non-solitary to solitary sleeping arrangements (16% vs. 48%), and more likely than European Americans to move their infants from non-bed sharing to bed sharing arrangements (21% vs. 1%). Thus, pertinent analyses controlled for mothers’ ethnicity (ANCOVAs). Because maternal emotional and marital functioning was highest among mothers of infants in solitary sleep arrangements at 1 and 6 months, an initial ANCOVA was conducted that compared stable solitary sleeping and nonsolitary to solitary sleeping change groups on 1-month marital adjustment, positive co-parenting, negative co-parenting, and depressive symptoms. There were no differences between these two change groups on any of these 1-month measures. These findings, along with those reported above, indicated that high levels of personal and marital functioning was associated both with consistent use of infant solitary sleep arrangements and movement from non-solitary to solitary sleep arrangements. These two subgroups were thus combined and used for comparison with other infant sleep change groups. Subsequent ANCOVAs, controlling for ethnicity, were conducted that incorporated planned comparisons between this combined solitary sleep group with the four remaining change groups. These analyses revealed significant change group differences, with effect sizes of moderate magnitude, in 1-month positive co-parenting, F(4, 130) ¼ 3.00, p ¼ .021, partial h2 ¼ 8%, and 1-month negative co-parenting, F(4, 130) ¼ 3.79, p ¼ .01, partial h2 ¼ 10%, but not in 1-month marital adjustment or maternal depressive symptoms (see Table 4). Post-hoc comparisons revealed that mothers in stable bed sharing arrangements from 1 to 6 months had significantly lower 1- month positive co-parenting scores (p < .01), and significantly higher 1-month negative co-parenting scores (p < .001), than mothers in the combined solitary sleep group.

DISCUSSION

As predicted, there was a strong shift in the number of infants who moved from non-solitary to solitary sleeping arrangements from 1 to 6 months, which is consistent with earlier work on U.S. families and with Western cultural norms that value solitary infant sleep over alternative sleeping arrangements (McCoy et al., 2004; Mindell et al., 2010). In light of the U.S. cultural norms supporting solitary infant sleep, it was not surprising that almost all mothers (>90%) of infants in solitary sleeping arrangements at 1 and 6 months strongly preferred their current sleep arrangement with their infants, as compared with mothers in room sharing (about 60%), bed sharing 171

(about 40%), and combination arrangements (about 20%) who strongly endorsed their choices. Also not surprising, given these cultural norms, was that the most stable sleeping arrangement from 1 to 6 months was solitary sleep, with 98% of infants in solitary sleeping arrangements at 1 month remaining in solitary sleep at 6 months. Results of the present study support and extend earlier work (Dollberg et al., 2010; Germo et al., 2007) in finding concurrent associations between infant sleep arrangements, marital adjustment, and co-parenting. Mothers of bed sharing infants reported less favorable co-parenting at 1 and 6 months, and higher levels of depressive symptoms at 6 months, as compared with mothers of infants in solitary sleeping arrangements, but no differences were found between bed sharing mothers and mothers in room sharing and combination arrangements. It was unclear from these concurrent associations, however, whether mothers’ marital harmony, co-parenting, and wellbeing were being compromised in response to mothers’ decisions to bed share, or whether less favorable marital and personal distress shaped mothers’ decision to share a bed and spend more time with their infants at night. Subsequent analyses, examining predictors of change in sleep arrangements and change in co-parenting and personal distress, appeared to give greater support to the premise that co-parenting quality may have influenced decisions regarding infant sleep arrangements. Mothers with the most favorable co-parenting scores at 1 month were mothers whose infants were in stable solitary sleeping arrangements from 1 to 6 months and mothers who moved their infants out of non-solitary to solitary sleeping arrangements between 1 and 6 months. By contrast, the lowest co-parenting adjustment at 1 month was associated with mothers of infants in stable bed sharing arrangements. This latter group had significantly lower 1-month co-parenting scores than mothers of infants in stable solitary sleep or who moved their infants into solitary sleep from 1 to 6 months. Although maternal co-parenting quality at 1 month predicted stability and change in sleep arrangements from 1 to 6 months, additional longitudinal analyses found no predictive associations between 1-month sleep arrangements and changes from 1 to 6 months in mothers’ positive or negative co-parenting and depressive symptoms. These analyses are correlational and must be interpreted with caution, but they suggest that mothers’ perceptions of co-parenting quality during infants’ first month of life may influence decisions about how infant sleep is structured during the first six months. Indeed, lower co-parenting quality was predictive of decisions to keep infants in bed sharing arrangements and higher levels of co-parenting quality was predictive of decisions to keep infants in solitary sleeping arrangements or move infants into solitary sleep arrangements across the first six months. These findings are consistent with those of Teti and Crosby (2012), who in a cross-sectional sample of infants between 1 and 172

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24 months-of-age found that mothers with elevated depressive symptoms were more likely to seek out and spend time with their infants during the night than nondepressed mothers. Although the present, short-term longitudinal study found no associations between 1-month maternal depressive symptoms and stability and change in sleep arrangements, mothers in bed sharing arrangements were found, by 6 months, to have significantly elevated depressive symptoms at the same point in time relative to mothers whose infants slept in separate rooms. These results must be viewed with caution, because the mothers in this study were not assessed for clinical depression, nor were they screened at recruitment to determine if they had elevations in depressive symptoms. However, to the extent that maternal distress predisposes mothers to spend more time with their infants at night, perhaps this tendency begins with marital and co-parenting distress experienced during the very first few months postpartum, with depressive symptoms playing a larger role at later infant ages. Decisions about how to structure infant sleep are highly personal and complex, and the reasons why marital and/or emotionally distressed mothers might be predisposed to seek out and spend more time with their infants at night than nondistressed mothers are not clear. We offer, however, that one reason for doing so may be to satisfy mothers’ needs for intimacy and emotional security, needs that perhaps are not being satisfactorily met in the marriage. This is an important and under-studied family-level dynamic that begs for further study. The present study is consistent with Tikotzky et al. (Chapter VII, in this volume), who found that paternal involvement, identified as an important feature of good co-parenting (Isaaco, Garfield, & Rogers, 2010), was predictive of better infant and maternal sleep at 6 months. Further, in their longitudinal study of sleep development in middle childhood, El-Sheikh et al. (Chapter VI, in this volume) reported that marital quality played a critically important role in predicting children’s sleep quality, particularly among children with poor vagal regulation. Data from these and many other laboratories (c.f., Be´langer et al., Chapter VIII, in this volume) appear to converge on the same conclusion: Sleep in childhood is multiply determined and influences and is influenced by processes embedded within family and ecological systems. It behooves developmental scientists to identify these mutual, transactional influences and how they differ across different family configurations and cultural contexts. Limitations

This study had several limitations. First, the generalizability of this study was hampered by the low percentage of ethnic minority families (14%). Cosleeping arrangements tend to be more accepted in minority American 173

cultures such as Asian Americans (Lozoff, Wolf, & Davis, 1984; Madansky & Edelbrock, 1990) and traditional African American and Latino communities (Milan, Snow, & Belay, 2007), and this was borne out in the present study. Second, although maternal depressive symptoms, marital adjustment, and coparenting values ranged widely, the present sample was, in the main, relatively nondistressed, and this could have impeded our ability to detect significant associations between study variables. Third, this study was conducted in the United States, a culture that supports solitary, independent infant sleep over other sleeping arrangements. It is unclear whether the patterns observed in this study would be replicated in a culture that supports co-sleeping. In addition, studying linkages between non-solitary sleep arrangements and parental functioning in a culture that supports solitary sleep can be compromised by low cell sizes for non-solitary sleep arrangements. Indeed, this was evident in the present study, particularly by 6 months of infant age. Fourth, we did not examine linkages between sleep arrangements and infant (and parental) sleep quality in this study, variations in which could contribute uniquely to parental mood and marital quality (McDaniel & Teti, 2012). Fifth, this study was limited by its sole use of maternal report (marital distress, co-parenting distress, sleep arrangements), the relatively small numbers of nontraditional (non-solitary) sleep arrangements, effect sizes that were sometimes small in magnitude, and the fact that, despite the longitudinal design used, directions of effects are at best implied but not confirmed. Lastly, this study was limited by the absence of data on fathers’ depressive mood and marital and co-parenting perceptions and the role that fathers play in sleep arrangement decisions. Future Directions

The present study underscores the crucial role played by family processes in shaping child and parent sleep. Co-parenting quality in this study was consistently associated, concurrently and predictably, with parents’ choice of sleep arrangements for their infants, which in turn has implications for parent and infant sleep quality. Countermine and Teti (2010), for example, found that shared parent-infant sleep (room or bed sharing) was associated with poorer maternal sleep efficiency and poorer maternal adaptation to infant sleep patterns than nonshared sleep. Future work might be aimed at identifying families experiencing marital distress (perhaps even before the birth of a new baby), as well as coparenting distress in the early postpartum period, as possible targets for intervention. In addition, we believe the field could benefit from a more time-intensive study of sleep arrangement choices across the first six months postpartum, focusing on the marital, coparenting, and parenting processes that either predict or result from these choices as they unfold over time. 174

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CONCLUSION

We appreciate fully that the choices parents make about infant sleep arrangements are complexly determined, drawing from philosophical perspectives, pragmatic concerns, and parents’ appraisals of evolving familial conditions (McKenna & Volpe, 2007). Our findings nevertheless suggest that attention should be paid to the potential influence of marital and coparenting quality during the early transition to parenthood on sleep arrangement choices. In the present study, bed sharing in particular appeared to be associated with more stressed co-parenting antecedents. We understand that bed sharing may be a very convenient and reasonable option for mothers who are breastfeeding and/or who wish to enjoy being close to their infants at night, if safely practiced. Our data lead us to question, however, whether bed sharing should be practiced if it is done at the expense of the marital relationship. We hope this study stimulates further work on this topic.

ACKNOWLEDGMENTS

We thank the many graduate and undergraduate students who have assisted in data collection for this study, and to Cori Reed and Renee Stewart for their project coordinating talents. Special thanks are extended to the families who participated in this study.

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