Infant Skin‐to‐Skin Contact on Postpartum Depressive Symptoms and Maternal Physiological Stress

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Effect of Mother/Infant Skin-to-Skin Contact on Postpartum Depressive Symptoms and Maternal Physiological Stress Ann Bigelow, Michelle Power, Janis MacLellan-Peters, Marion Alex, and Claudette McDonald

Correspondence Ann Bigelow, PhD, St. Francis Xavier University, Box 5000, Antigonish, Nova Scotia B2G 2W5, Canada. [email protected]

ABSTRACT Objective: To investigate the effect of mother/infant skin-to-skin contact (SSC) on mothers’ postpartum depressive symptoms during the first 3 postpartum months and their physiological stress during the first postpartum month. Design: Longitudinal quasi-experiment. Setting: Data were collected during home visits.

Keywords mother/infant skin-to-skin contact postpartum depressive symptoms maternal stress salivary cortisol

Participants: Mothers in the SSC group (n = 30) provided approximately 5 hours per day of SSC with their infants in the infants’ first week and then more than 2 hours per day until the infants were age one month. Mothers in the control group (n = 60) provided little or no SSC. All mothers had full-term infants. Methods: Mothers completed self-report depression scales when infants were 1 week, 1 month, 2 months, and 3 months of age. Results: Compared to mothers in the control group, mothers in the SSC group had lower scores on the depression scales when the infants were one week and marginally lower scores when the infants were one month; when the infants were age 2 and 3 months, there were no differences between groups in the mothers’ depression scores. Over their infants’ first month, mothers in the SSC group had a greater reduction in their salivary cortisol than mothers in the control group. Conclusion: Mother/infant SSC benefits mothers by reducing their depressive symptoms and physiological stress in the postpartum period.

JOGNN, 00, 1-14; 2012. DOI: 10.1111/j.1552-6909.2012.01350.x Accepted January 2012

Ann Bigelow, PhD, is a professor in the Psychology Department, St. Francis Xavier University, Antigonish, Nova Scotia, Canada. Michelle Power, BSc, is a research laboratory manager in the Psychology Department, St. Francis Xavier University, Antigonish, Nova Scotia, Canada.

(Continued)

The authors report no conflict of interest or relevant financial relationships.

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he postpartum period brings physiological and psychological transitions that predispose a large number of women to depressive symptoms. In a meta-analysis of rates of postpartum depressive symptoms conducted over a decade ago, approximately 13% of mothers were affected with symptoms of postpartum depression (O’Hara & Swain, 1996). More recent large sample studies showed that the incidence of symptoms is between 20% and 40% in the first 6 weeks after delivery (McCoy, Beal, Shipman, Payton, & Watson, 2006; Morris-Rush, Freda, & Bernstein, 2003). Postpartum depressive symptoms can involve experiences of mental confusion, despair, sadness, anxiety, fear, compulsive thinking, and feelings of inadequacy (Horowitz & Goodman, 2005). The

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risks of symptoms are higher for women living in poverty (O’Hara & Swain) and for those with ill or preterm infants (Lefkowitz, Baxt, & Evans, 2010; Poehlmann, Schwichtenberg, Bolt, & DilworthBart, 2009), yet postpartum depressive symptoms are prevalent in all socioeconomic groups and across cultures (Goldbort, 2006), including mothers with healthy, full-term infants. Depressive symptoms affect women’s happiness, ability to function, and general quality of life. Mothers with postpartum depressive symptoms do not necessarily have clinical postpartum depression, which involves a major depressive episode within 3 months of delivery (American Psychiatric Association, 2000). Yet postpartum

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Janis MacLellan-Peters, RN, MN, is an assistant professor in the Psychology Department, St. Francis Xavier University, Antigonish, Nova Scotia, Canada. Marion Alex, RN, MN, CNM, is an associate professor in the School of Nursing St. Francis Xavier University, Antigonish, Nova Scotia, Canada. Claudette McDonald, BScN, RN, is an instructor in the Nova Scotia Community College, Dartmouth, Nova Scotia.

Mother/Infant Skin-to-Skin Contact, Postpartum Depressive Symptoms, and Maternal Physiological Stress

depressive symptoms put women at higher risk for clinical depression, leading researchers to consider postpartum depressive symptoms to be on a spectrum of mood disturbances during this period (Zonana & Gorman, 2005). Typically, postpartum depressive symptoms are measured with self-report indices, the most common of which are the Edinburgh Postnatal Depression Scale (Cox, Holden, & Sagovsky, 1987) and the Center for Epidemiological Studies Depression Scale (CESD; Center for Epidemiologic Studies, 1998). On each of these scales, mothers are asked to rate how well statements match their current feelings or how frequently they recently had the thoughts or feelings indicated in the statements. The scales are not diagnostic tests but have high reliability with clinical assessments of depression, making them valid screening tools (McCoy et al., 2006; Radloff, 1977). Postpartum depressive symptoms are of particular concern because of the effect on the infant as well as the mother. Infants of mothers with these symptoms are at risk for developmental difficulties in cognitive, social, and emotional realms. Mothers with postpartum depressive symptoms often show disturbances in their interactions with their infants. They tend to be less sensitive and responsive to their infants, less engaged, more irritable, less playful, and show less emotion and warmth (Field, 2010; Lovejoy, Graczyk, O’Hare, & Neuman, 2000). These differences in maternal behavior between mothers with and without depressive symptoms are found across a variety of cultures (Danaci, Dinc¸, Deveci, Sen, & Ic¸elli, 2002; Goldbort, 2006). In mother/infant interactions, mothers without depressive symptoms typically are responsive to infants’ behavior. The mothers reflect to infants the emotional content they perceive the infants to be feeling, mirroring the infants’ behavior back to them in an exaggerated, imitative manner (Gergely & Watson, 1996, 1999). By experiencing responsiveness in their interactions with their mothers, infants develop a sense of self-agency, which involves an awareness that their actions have external consequences that can become predictable (Neisser, 1991). Mothers with depressive symptoms tend to have minimal contingent responsiveness and reduced synchronous behavior with their infants, which impairs infants’ ability to detect the effect of their own behavior on others. Extended experience with minimal responsiveness in maternal interactions results in difficulties in the infants’ ability to sense their self-agency, which impairs infants’ sociocognitive functioning (Bigelow, 1999).

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Mothers with postpartum depressive symptoms often are untreated, which can result in increased symptoms. Interventions, when they occur, are focused primarily on pharmaceuticals and psychotherapy. Antidepressants may have side effects for these mothers. Caution must be used with mothers who are breastfeeding because antidepressants are excreted in breast milk (Thompson & Fox, 2010; Wisner, Parry, & Piontek, 2002) and may have adverse effects on infants’ cognitive functioning (Field, 2008). Psychotherapy can affect positive outcomes (Horowitz & Goodman, 2005), but barriers such as location and cost of services as well as family and community factors may limit the access to these services for many women in need. Mother/infant skin-to-skin contact (SSC) is a possible alternative or complementary intervention that is easily accessible to all mothers. Mother/infant SSC is a method of holding young infants. The infant is placed between the mother’s breasts dressed only in a diaper so that frontal body contact of mother and infant is skin to skin; the infant is secured and the mother is covered. In this way, the mother provides warmth and stimulation that simulates the prenatal environment. In the 1970s, Drs. Rey and Martinez began using the method in Colombia as a means of treating premature infants when incubators were overcrowded (Whitelaw & Sleath, 1985). The infants survived as well or better in SSC at home than if they remained in incubators in hospital. The benefits of mother/infant SSC for newborns’ neurophysiological adjustment to postnatal life have been extensively researched (Charpak, Ruiz-Pelaez, & Figueroa de Calume, 1996; Ludington-Hoe & Swinth, 1996; Moore, Anderson, & Bergman, 2007). Studies have shown that compared to newborns who do not have SSC with their mothers, newborns with SSC have more stable temperatures, heart rates, respiratory rates, and gastrointestinal adaptation (Bauer, Sontheimer, Fischer, & Linderkamp, 1996; Cleary, Spinner, Gibson, & Greenspan, 1997; CondeAgudelo, Diaz-Rossello, & Belizen, 2000; Feldman, Eidelman, Sirota, & Weller, 2002; Fohe, Kropf, & Avenarius, 2000; Ludington-Hoe, Anderson, Swinth, Thompson, & Hadeed, 2004; Moore et al., 2007). The infants’ sleep is more restful (Feldman & Eidelman, 2003; Messmer et al., 1997), they cry less (Christensson et al., 1992; Christensson, Cabrera, Christensson, Uvnas-Moberg, & Winberg, 1995; Ferber & Makhoul, 2004; Michelsson, Christensson, Rothganger, & Winberg, 1996), grow faster (Bergman & Jurisoo, 1994; Lincetto

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Bigelow, A., Power, M., MacLellan-Peters, J., Alex, M., and McDonald, C.

et al., 1998; Rojas et al., 2003), breastfeed longer (Bramson et al, 2010; Charpak, Ruiz-Pelaez, Figueroa de Calume, & Charpak, 2001; Meyer & Anderson, 1999), and experience less pain from routine procedures (Castral, Warnock, Leite, Haas, & Scochi, 2007; Gray, Miller, Philipp, & Blass, 2002; Gray, Watt, & Blass, 2000). The effects of SSC on maternal behavior have been less well researched. In past studies, mothers who provided SSC for their infants reported more positive feelings toward their infants, more positive perceptions of the infants, less depression, and more empowerment in their parenting role (Affonso, Bosque, Wahlberg, & Brady, 1993; Johnson, 2007; Neu, 1999; Roller, 2005; Tessier et al., 1998; Whitelaw, 1990). Most of these studies, however, were conducted only in the newborn period. Nevertheless, the findings suggest that SSC increases mothers’ positive feelings toward their infants and enhances mothers’ mood states, lessening depressive symptoms. The research specifically focused on exploring the effects of mother/infant SSC on mothers’ depressive feelings in the postpartum period is sparse. Dombrowski, Anderson, Santori, and Burkhammer (2001) report a case study of a mother identified in a randomized control trial who presented with several clinical indicators of postpartum depression. The mother’s self-reported depressive symptom scores decreased rapidly during several hours of SSC with her infant over the baby’s first few days of life. The mother continued SSC after discharge. Follow-up at 6 weeks, 3 months, and 7 months indicated the mother’s depressive symptoms were gone. In an unpublished report of a randomized control trial, Dombrowski and Anderson (2002, September) found that mothers who provided SSC to their infants had lower depressive symptom scores than mothers who did not provide SSC. De Alencar, Arraes, de Albuquerque, and Alves (2009) investigated the effect of SSC on postpartum depressive symptoms in Brazilian low-income mothers of preterm infants. In this study, infants were in Neonatal Intensive Care Units (NICUs) until stabilized and then transferred to Kangaroo Care Units (KCUs), where mothers provided a minimum of one hour per day of SSC to their infants. Mothers were assessed for depressive symptoms when their infants were admitted to the NICUs and when they were discharged from the KCUs at a mean age of 49 days. During this time, the incidence of depressive symptoms in these mothers dropped from 37% to 17%. How-

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ever, the study did not include a control group of mothers who did not engage in SSC. In addition to being more predisposed to depressive symptoms during the postpartum period, mothers may experience more stress at this time. One of the least invasive means of measuring physiological stress is salivary cortisol. Cortisol, which is present in saliva, is a product of hormones produced by the limbic-hypothalamic-pituitaryadrenocortical (L-HPA) axis (Mason, 1968). The L-HPA axis is a component of the stress response system and a regulator of social and emotional behavior (Gunnar & Donzella, 2002; Stansbury & Gunnar, 1994). Individual differences in salivary cortisol reflect individual differences in physiological stress. Cortisol levels increase during pregnancy and tend to drop abruptly after delivery (Carter, Altermus, & Chrousos, 2001). Most studies examining depressive symptoms and cortisol levels in pregnant women have found a positive relationship (Field et al., 2004; Field, HernandezReif, Diego, Schanberg, & Kuhn, 2006). Yet in the few studies that have investigated the relationship between postpartum women’s cortisol levels and their depressive symptoms, the findings have been mixed. Ehlert, Patalla, Kirschbaum, Piedmont, and Hellhammer (1990) found postpartum women with depressive symptoms had elevated salivary cortisol levels in the first 5 days after their healthy infants’ birth. Yet Dombrowski and Anderson (2002, September) found no correlation between mothers’ depressive symptom scores and cortisol levels in the first 5 postpartum days. Howland, Pickler, McCain, Glaser, and Lewis (2011) found that, when mothers with preterm infants in NICUs were dichotomized into two groups based on high and low depressive symptoms, mothers with higher depressive symptoms had higher cortisol levels than mothers with lower depressive symptoms. Cheng and Pickler (2010) found no relationship between depressive symptoms and maternal cortisol levels when measured 4 to 6 weeks after their full-term infants’ birth. Depressive symptomatology and elevated physiological stress may be independent risk factors for women in the postpartum period. Yet both may be affected by SSC. In the only published study to examine the effect of SSC on maternal cortisol levels, Morelius, ¨ Theodorsson, and Nelson (2005) assessed mothers’ salivary cortisol before, during, and after their first and fourth hour-long SSC sessions with their preterm infants in NICUs when the infants were a

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A readily accessible and cost-effective intervention to reduce postpartum depressive symptoms and maternal stress is needed.

few days old. Mothers’ levels of salivary cortisol decreased following the SSC sessions. The purpose of this study was to investigate the effect of SSC on postpartum depressive symptoms and maternal physiological stress in a community sample of mothers of full-term infants. Mothers in SSC and control groups were assessed on self-report scales for depressive symptoms when their infants were one week, one month, 2 months, and 3 months of age. When the infants were one week and one month, saliva samples were taken from the mothers and assessed for cortisol. The hypotheses were that mothers who engaged in SSC with their infants would have fewer depressive symptoms and have lower salivary cortisol than mothers who did not engage in SSC.

Method Design In a longitudinal quasi-experiment, mothers in the SSC group were requested to provide daily SSC with their infants through the infants’ first month; mothers in the control group received no request to provide mother/infant SSC. The mothers were recruited for the study prior to the birth of their infants through perinatal clinics at two hospitals with similar demographics in eastern Canada. The recruitment was conducted concurrently at both hospitals between the years 2004 and 2007. One hospital recruited for the SSC group, and one hospital recruited for the control group. Approximately halfway through the study, the recruitment sites were switched; the former SSC site became the control site and vice versa. Mothers completed self-report depression scales when their infants were age one week, one month, 2 months, and 3 months. Mothers’ saliva samples were assayed for cortisol when the infants were one week and one month of age.

their group. The criterion for inclusion in the SSC group was that the mothers provided more than 4,000 minutes of SSC in the infant’s first month; the criterion for inclusion in the control group was that the mothers provided fewer than 4,000 minutes of SSC in the infant’s first month. As can be seen on Figure 1, of the original 113 women recruited into the study (48 in the SSC group, 65 in the control group), 23 were excluded: one because the infant was born at fewer than 37 weeks (one from the control group), three because of medical problems with the infant (three from the SSC group), 17 because the SSC criterion for the group was not met (14 from the SSC group, three from the control group), and two because of experimental error (one from the SSC group, one from the control group). The excluded mothers did not differ from the 90 participating dyads in maternal age, education, socioeconomic status, race, number of previous births, initial choice to breast or bottle feed the infants, infants’ birth weight, birth length, birth head circumference, or Apgar score, although the excluded mothers had a higher percentage of male infants (81%). Socioeconomic status (SES) of the mothers was measured by a Canadian index (Blishen, Carroll, & Moore, 1987) based primarily on education, income, and to lesser extent on occupational prestige. In the index, occupations are divided into 514 groups, ranging in SES scores from 17.81 to 101.75 (M = 42.74, SD = 13.28). The scores of the mother or her partner, whoever had the higher score, yielded an SES mean score of 49.78 (SD = 12.05). The percentage of mothers with a university degree was 42%, 39% had some university or postsecondary education, 16% had a high school diploma with no further education, and 3% were without a high school diploma. The mean age of the mothers was 29.4 years (SD = 5.1 years). The racial-ethnic composition of the mothers was 99% non-Hispanic White and 1% Asian. For 49% of the mothers, this was their first child, 29% of the mothers had one previous child, and 22% of the mothers had two or more previous children. Most of the mothers initially chose to breastfeed their infants (77%).

Participants The participants were 90 postpartum women, 30 in the SSC group and 60 in the control group. The participants’ infants were older than 37-weeks gestation age and had no medical problems; the women had no immediate postpartum complications and met the SSC criterion for inclusion in

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Intervention Mothers in the SSC group were requested to provide 6 hours of SSC with their infants cumulative throughout the day during the infants’ first week of life, and then 2 hours per day until the infants were one month of age. In SSC, the infant is placed

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Bigelow, A., Power, M., MacLellan-Peters, J., Alex, M., and McDonald, C.

RESEARCH

Figure 1. Flow diagram of the number of mothers enrolled, the number recruited to the skin-to-skin contact (SSC) and control groups, the number excluded from each group, and the number analyzed in each group.

between the mother’s breasts dressed only in a diaper so that frontal body contact of mother and infant is skin to skin; then the infant and mother are covered. No request for mother/infant SSC was made to control group mothers. Mothers in the SSC and control groups recorded the amount of SSC they provided for their infants each day.

Measures Depression Scales. Two self-report questionnaires were used: the Edinburgh Postnatal Depression Scale and the Center for Epidemiological Studies Depression Scale (CES-D). These scales are similar in format and widely used in postpartum research. Researchers recommend adminis-

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tering both scales to provide an assessment of depressive symptoms during this time (Breedlove & Fryzelka, 2011). The Edinburgh Postnatal Depression Scale (Cox et al., 1987) consists of 10 statements. On a scale of 0 to 3, mothers are asked to indicate to what extent each statement corresponds to how they have been feeling during the past week. An example statement is “I have looked forward with enjoyment to things,” to which the responses range from 0 (as much as I ever did) to 3 (hardly at all). The scores can range from 0 to 30. Mothers who score above 13 are considered at risk for postpartum depression. The Edinburgh has high reliability (.88) and validity (positive predictive value of 73% for women who meet

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diagnostic criteria for depression) (Cox & Holden, 2003). The CES-D (Center for Epidemiologic Studies, 1998; Radloff, 1977) is a more general selfadministered depression scale that has shown good reliability when assessing depressive symptoms in women during the perinatal period (Cheng & Pickler, 2010; Miles, Holditch-Davis, Schwartz, & Scher, 2007). It consists of 20 statements; persons indicate how frequently, on a scale of 0 to 3, they had the thoughts or feelings described in the statements during the past week. An example statement is “I felt that everything I did was an effort”, to which the responses range from 0 (rarely or none of the time) to 3 (most or all of the time). The scores can range from 0 to 60. Persons with scores of 16 or more are considered at risk for depression. The CES-D has high reliability in community samples (.85) and good validity with clinical diagnostic ratings for depression (.56) (Radloff, 1977; Riem, Pieper, Out, Bakermans-Kranenburg, & van IJzendoorn, 2011). Neither scale is a diagnostic tool; they are screening devices. Salivary Cortisol. Saliva samples were collected from the mothers and assayed for cortisol.

Procedure After the study received ethical clearance from the two participating hospitals, the perinatal clinics in the two hospitals distributed Consent to be Contacted Forms to pregnant women in the third trimester of their pregnancy. The women who signed the form were contacted by a research assistant. In the contact interview, the study was explained, the women had opportunity to ask questions to clarify what was being asked of them, and, if they agreed to participate, they signed consent forms. Notice that these women had agreed to participate in the study was put on their medical charts so that attending nurses would notify the research assistants when the women gave birth. Research assistants (N = 8) were women with maternal/child experience either in nursing or child care. They were given a manual detailing the protocol and learned the procedures in a day-long training session. They also participated in a multiday training and certification on measures (e.g., Nursing Child Assessment Feeding Scale) not included in this report. Mothers were seen by the same research assistant from the contact interview through the data collection visits. The research assistants met with the participating mothers in the hospital on the day of their in-

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fants’ birth to review the procedure and to give the mothers their first record sheet to record their daily mother/infant SSC. On the record sheet, the mother logged the time of day and length of each SSC period with her infant. Data collection occurred in the home on morning visits when the infants were one week (M = 8 days, SD = 2 days), one month (M = 32 days, SD = 5 days), 2 months (M = 64 days, SD = 8 days), and 3 months (M = 93 days, SD = 9 days) of age. This article presents the results from the mothers’ scores on the self-report depression scales completed at each home visit and the mothers’ cortisol assays from saliva samples taken at the one-week and one-month visits. On each home visit, while the research assistant looked after the infant, the mother completed the Edinburgh Postnatal Depression Scale and the CES-D. If a mother scored within the risk range on either scale, the research assistant encouraged the mother to contact her doctor and/or a mental health professional. On the one-week and one-month visits, saliva samples were collected from the mother. Subsequently, these samples were assayed for cortisol. To control for diurnal changes in cortisol production, the samples were collected between 10:00 and 11:00 in the morning. Care was taken that, prior to sampling, the mother had not consumed a meal within one hour, dairy products within 30 minutes, or caffeine within 2 hours. The mother held an absorbent dental cotton roll in her mouth for approximately 2 minutes. The cotton roll was then sealed in a container and immediately refrigerated. The saliva samples were frozen for storage until they were shipped in dry ice to the Salimetrics Lab at Pennsylvania State University for the cortisol assays. Two mothers had missing cortisol assay data for the one-week visit and four mothers had missing data for the one-month visit; the missing values were all due to an insufficient quantity of saliva collected. One of the mothers’ salivary cortisol assays for the one-week visit was an outlying value, defined as a value greater than three SDs above the mean for the salivary cortisol assays. This value was replaced by the closest nonoutlying value (Tukey, 1997) for the one-week visit.

Data Analyses General linear ANOVAs were conducted on the demographics of the mothers and infants in the SSC and control groups. Correlations were

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Bigelow, A., Power, M., MacLellan-Peters, J., Alex, M., and McDonald, C.

conducted within and across the mothers’ scores on the Edinburgh Postnatal Depression Scale and the CES-D and the mothers’ salivary cortisol values. Initial overall ANOVAs, using mixed linear models, with the repeated variable visit (1 week, 1 month, 2 months, 3 months) and betweensubjects variable group (SSC, control), were conducted on the mothers’ Edinburgh and CES-D scores. Mixed linear models allow for flexibility in modeling the dependency of repeated measures but do not require that there be complete data at each age. Seven of the mothers missed one of the four visits, two of the mothers missed two of the visits, and eight of the mothers missed three of the visits. These analyses were followed by general linear ANOVAs, with the between-subjects variable group (SSC, control), on the mothers’ Edinburgh and CES-D scores for each visit. General linear ANOVAs, with the between-subjects variable group (SSC, control), were conducted on the mothers’ salivary cortisol assay values when the infants were age one week and one month. Cortisol assay values were log10 transformed for analyses because of skewness of the distributions. Difference scores on the nontransformed values were calculated by subtracting the one-month assay values from the one-week assay values. A general linear ANOVA on the difference scores, with the between-subjects variable group (SSC, control), was conducted. The difference scores were normally distributed and did not require transformation.

Results Table 1 shows the demographics of the mothers and infants in the SSC and control groups. There were no significant differences between the SSC and control group mothers in education, number of previous births, socioeconomic status, race, or whether they initially chose to breastfeed their infants (all ps > 0.05). The mothers in the SSC group were slightly older than the mothers in the control group. Infants in the SSC and control groups did not differ in sex, Apgar score, birth weight, birth length, or birth head circumference (all ps > 0.05). Table 2 shows the mean amount of SSC that mothers in the SSC and control groups provided for their infants during the infants’ first week and in weeks 2 through 4. Mothers in the SSC group provided just over 5 hours of SSC per day in their infants’ first week, which is less than the 6 hours per day requested, but almost 3 hours per day in weeks 2 through 4, which is more than the requested 2 hours per day. Mothers in the control

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group provided little or no SSC throughout the infants’ first month. The correlations between the Edinburgh and CESD scores were significant within and across all the visits (r range: .304 to .870, all ps < 0.01). The correlation between mothers’ cortisol assays at the one-week and one-month visits was significant, r (75) = .430, p < 0.001. However, correlations among the scores on the postpartum depression scales and the cortisol assays were nonsignificant. Initial overall mixed linear ANOVAs conducted on the mothers’ Edinburgh and CES-D scores revealed the following results. For scores on the Edinburgh, there was a significant main effect for visit, F(3, 235) = 17.546, p < 0.001, and a significant Group × Visit interaction, F(3, 235) = 3.454, p = .017. For scores on the CES-D, there was a significant main effect for visit, F(3, 223) = 10.756, p < 0.001, and a significant Group × Visit interaction, F(3, 223) = 2.688, p = .049. Figures 2 and 3 show the Edinburgh and CES-D scores on each visit for the mothers in the SSC and control groups. In follow-up ANOVAs on the mothers’ Edinburgh scores for each visit, there was a significant group effect at the one-week visit, F(1, 88 = 7.755, p = .007, η2p = .081; a marginally significant group effect at the one-month visit, F(1, 80 = 3.195, p = .078, η2p = .038; and no significant effect at the final two visits. In follow-up ANOVAs on the mothers’ CES-D scores for each visit, there was a significant group effect at the one-week visit, F(1, 87) = 5.250, p = .024, η2p = .057, and no significant effect at the following visits. The depressive symptom scores were below the risk zones (risk scores were above 13 on the Edinburgh and 16 or above on the CES-D) for most of the mothers in both groups. However, 17 mothers had scores in the risk zone on at least one of the self-report measures: 10 mothers at the one-week visit (SSC group = 1; control group = 9), seven mothers at the one-month visit (SSC group = 1; control group = 6), and three mothers at the twomonth visit (SSC group = 1; control group = 2). Only two mothers, who were in the control group, scored in the risk zone for more than one visit. The mean values for salivary cortisol assays for the one-week visit were .340 μg/dL (SD = .163) for the SSC group and .278 μg/dL (SD = .128) for the control group. The mean values for the one-month visit were .234 μg/dL (SD = .095) for

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Table 1: Demographics of the Mothers and Infants in the Skin-to-Skin and Control Groups Mother Variables

Skin-to-Skin Group M (SD)

Control Group M (SD)

31.7 (5.9)

28.3 (4.2)

Socioeconomic status (SES)

49.9 (14.0)

49.7 (11.1)

Education

3.4 (0.7)

3.1 (0.9)

1.1 (0.7)

1.2 (0.7)

Race

100% non-Hispanic White

98% non-Hispanic White, 2% Asian

Initially chose to breastfeed

83%

73%

Birth weight in grams

3640.9 (439.4)

3608.7 (593.3)

Birth length in cm

52.6 (2.4)

52.5 (2.5)

Birth head circumference in cm

35.3 (1.4)

34.8 (1.8)

Apgar at 5 minutes

9.9 (0.3)

9.8 (0.6)

Sex

48% male

48% male

∗

Age in years

a

1 = without high school diploma 2 = high school diploma only 3 = some university/postsecondary education 4 = university degree Number of other children 1 = no previous child 2 = 1 previous child 3 = 2 or more previous children

Infant variables

∗ SSC and control group significantly different (p < 0.01). Note. a SES scores of the mother or her partner, whoever had the higher score, on a Canadian index (Blishen, Carroll, & Moore, 1987).

the SSC group and .244 μg/dL (SD = .161) for the control group. ANOVAs, with the betweensubjects variable group (SSC, control), on the transformed (log10 ) assay values at one week and at one month were nonsignificant. Similar ANOVAs using the transformed assay values from only the mothers with salivary cortisol assays for the oneweek and the one-month visits were also nonsignificant. An ANOVA on the difference scores (one-week assay value minus one-month assay value), with the between-subjects variable group (SSC, control), showed a significant group effect, F(1, 75) = 4.172, p = .045, η2p = .053, indicating that mothers in the SSC group had a larger reduction in salivary cortisol over the infants’ first month than mothers in the control group.

Discussion Mother/infant SSC lessened mothers’ selfreported depressive symptoms and reduced mothers’ physiological stress in the first postpar-

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Table 2: Mean Hours per Day of Mother/ Infant Skin-to-Skin Contact for the Skinto-Skin and Control Groups during the Infants’ First Week of Life and during Weeks 2 through 4 Infant Age Group

Week 1

Weeks 2 through 4

Skin-to-skin

5.03 (1.33)

2.66 (1.22)

Control

0.46 (0.85)

0.15 (0.32)

Note. Standard deviations are in parentheses.

tum weeks. These findings provide support for the predictions. Mothers in the SSC group reported fewer depressive symptoms on the Edinburgh and the CES-D scales than mothers in the control group when the infants were age one week. When their infants were one month, mothers in the SSC group

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Bigelow, A., Power, M., MacLellan-Peters, J., Alex, M., and McDonald, C.

still scored significantly lower on the Edinburgh scale than mothers in the control group, although marginally so. The scores on both scales were highly correlated, indicating they tapped the same underlying symptomatology. The Edinburgh scale, however, was designed to screen for postpartum depressive symptoms, whereas the CES-D was designed to screen for more general depressive symptoms in men and women. Postpartum depression is distinguished from nonperinatal depression by a prominent anxiety component (Kabir, Sheeder, & Kelly, 2008). The Edinburgh scale has been found to be better than the CES-D at identifying mothers’ anxious depressive feelings (Cox & Holden, 2003) and may be more sensitive in tapping depressive symptoms in the postpartum period. By the time the infants were 2 and 3 months of age, there were no differences in the mothers’ scores in the SSC and control groups on either scale. In the first weeks of their infants’ lives, mothers face many transitions: physically, hormonally, behaviorally, and socially (Christie, Poulton, & Bunting,

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Mother/infant skin-to-skin contact lessened mothers’ depressive symptoms and reduced mothers’ physiological stress in the first postpartum weeks.

2008). Their bodies are adjusting to being in a nonpregnant state. Breastfeeding mothers are adjusting to lactation. Mothers’ sleep is disturbed, and their infants’ schedules are in flux. New mothers are adjusting to their new role. All family members are adjusting to the newborn. Thus the first few weeks of an infant’s life may be more emotionally demanding on the mother than later when the infant is a few months old. The depressive symptoms reported by the mothers, seen in Figures 1 and 2, support this reality. However, mothers who engaged in SSC experienced fewer depressive symptoms during this time. Most of the mothers scored below the risk zones on the self-report depression scales. These mothers were from a community sample with healthy,

Figure 2. Mean scores on the Edinburgh Postnatal Depression Scale for mothers in the skin-to-skin contact (SSC) and control groups on each visit. Vertical bars represent standard errors.

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Mother/Infant Skin-to-Skin Contact, Postpartum Depressive Symptoms, and Maternal Physiological Stress

Figure 3. Mean scores on the Center for Epidemiological Studies Depression Scale (CES-D) for mothers in the skin-to-skin contact (SSC) and control groups on each visit. Vertical bars represent standard errors.

full-term infants, rather than from a population known to be at high risk for postpartum depression. Yet the pattern of mothers scoring in the risk zones reflected the overall pattern of scores on the two depressive symptom scales. Mothers who scored in the risk zones were disproportionately higher in the control group than in the SSC group and the number of mothers scoring in the risk zones decreased on each visit as the infants aged. The mothers’ physiological stress was comparable between the groups at the one-week and one-month visits; mothers in the SSC and control groups did not differ in their salivary cortisol levels on either of these visits. Mothers were from a rural, relatively homogeneous population where individual differences are likely to be less variable and fluctuating than in more diverse samples. Indeed, the variability in salivary cortisol was low across the groups, and the correlation between the oneweek and one-month salivary cortisol levels was high. Nevertheless, when difference scores (salivary cortisol at one week minus salivary cortisol at

10

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one month) were used, mothers in the SSC group showed more reduction in salivary cortisol than mothers in the control group, indicating that mothers’ physiological stress in the infants’ first month was lessened to a greater extent in the SSC group than in the control group. Why might engaging in SSC with infants reduce mothers’ depressive symptoms and physiological stress over the infants’ early weeks? Reasons for this are complex. The benefits of SSC to infants’ postnatal physiological adjustment, such as reducing their crying, facilitating their sleep, and making them more physiologically stable, should in themselves reduce maternal stress. Yet SSC may have more direct benefits to mothers. Physiologically, the SSC between mothers and infants functions as an oxytocin-releasing agent (Bier et al., 1996). Oxytocin, a hormone produced during parturition and breastfeeding, also is produced through touch, caressing, and sustained physical contact (Insel, 1997; Uvnas-Moberg & Eriksson, 1996). Oxytocin is important to maternal affilitative behaviors and to positive maternal

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Bigelow, A., Power, M., MacLellan-Peters, J., Alex, M., and McDonald, C.

mood states (Carter, 1998; Uvnas-Moberg, 2003). Mother/infant attachment is a psychobiological process in which oxytocin plays a role. Maternal behaviors of touch, gaze, positive affective facial and vocal expression, as well as decreased maternal depressive symptoms may be related to underlying physiological processes along with psychological and social factors. Mothers’ oxytocin may be increased by engaging in SSC with their infants, resulting in mothers demonstrating more positive maternal behaviors, and also experiencing fewer postpartum depressive symptoms and becoming generally less stressed. In addition to the physiological effect on the mother, SSC may lessen depressive feelings and stress behaviorally by empowering women in their mothering role (Affonso et al., 1993; Johnson, 2007; Neu, 1999; Roller, 2005; Tessier et al., 1998; Whitelaw, 1990). The mother/infant relationship is transactional in that both partners influence each other and, therefore, the relationship. Yet mothers are primarily responsible for establishing and maintaining interactions with their infants, particularly in the infants’ early life. The close proximity of mother and infant in SSC facilitates mothers’ ability to recognize and become familiar with their infants’ signals. Mothers who are sensitive to their young infants’ signals engage in more frequent and positive mother/infant interactions. Positive mother/infant interactions in early infancy provide mothers with a sense of empowerment in their mothering role as well as predict continued positive mother/child interactions throughout infancy and secure attachment into the preschool years (Bigelow et al., 2010). SSC also affects infants’ ability to respond and attend to their mothers, which facilitates their interactions and is positively reinforcing for mothers. Newborn infants use much of their energy making physiological adjustments to postnatal life, and many of their physiological states (e.g., crying, sleeping) do not allow for taking in information from the external world. The one exception is the quiet alert state. There are large individual differences in the amount of time newborns spend in this state. Yet it is in this state that early cognitive and social developments begin (Lamb, 1982). SSC facilitates infants’ ability to move into and maintain the quiet alert state (Feldman, Weller, Sirota, & Eidelman, 2002), which allows infants to participate more actively in interactions with their mothers. Such behavior not only facilitates infants’ own growth and development but also fosters the mother/infant relationship.

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Limitations to the study are several. First, the mothers were not randomized into the SSC and control groups. Mothers were assigned to groups based on the hospital in which their infants were born. The hospitals were designated as either the SSC or control group site with the designation being switched halfway through the study. Thus mothers chose whether to participate in the study being conducted at their hospital at the time of their infants’ birth, but mothers did not bias the group composition by selecting which group they were in. Nevertheless, more mothers participated in the control group than in the SSC group. It is possible that mothers who were in the SSC group had more desire to engage with their infants in close physical contact than mothers in the control group. Yet the time request for SSC could have been a factor in deterring mothers from participating in the SSC group. Indeed, more mothers in the SSC group than the control group did not meet the SSC criterion for inclusion in their group (SSC group: more than 4,000 minutes in the infant’s first month; control group: fewer than 4,000 minutes in the infant’s first month). Although mothers were not asked for reasons why they provided the amount of SSC that they did, some mothers in the SSC group who did not provide the criterion amount of SSC volunteered that the requested amount was difficult to do because of demands from their other children. Second, mothers in the SSC and control groups were from a homogeneous community sample. The homogeneity of the sample controlled for differences due to maternal education, socioeconomic status, ethnicity, and race. The results from this community sample suggest that SSC lessens mothers’ depressive symptoms and reduces stress. However, whether mothers from more diverse or high-risk populations would show similar responses to SSC awaits further research. Third, mothers in the SSC and control groups did not differ on any of the measured demographics except age. Yet maternal age may be a factor affecting the outcome of the results, even though maternal age was not found to be a predictor of postpartum depressive symptoms in a meta-analysis examining demographic predictors (O’Hara & Swain, 1996). Fourth, the mothers’ SSC time with their infants was based on their own records. Although the relationship the research assistants formed with the mothers over the course of the study focused on support and nonjudgement so that the mothers would report their true feelings and behaviors,

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Mother/Infant Skin-to-Skin Contact, Postpartum Depressive Symptoms, and Maternal Physiological Stress

infants during kangaroo holding by their mothers and fathers.

Mother/infant skin-to-skin contact provides health benefits to mothers: it is a viable intervention to reduce postpartum depressive symptoms and maternal stress during the postpartum period.

Journal of Pediatrics, 129, 608–611. Bergman, N. J. & Jurisoo, L. A. (1994). The ‘kangaroo-method’ for treating low birth weight babies in a developing country. Tropical Doctor, 24, 57–60. Bier, J. B., Ferguson, A. E., Morales, Y., Liebling, J. A., Archer, D., Oh, W., & Vohr, B. (1996). Comparison of skin-to-skin contact with standard contact in low-birth-weight infants who are breastfed.

mothers’ records of their SSC time with their infants may not have been accurate.

Archives of Pediatric and Adolescent Medicine, 150, 1265–1269. Bigelow, A. E. (1999). Infants’ sensitivity to imperfect contingency in social interaction. In P. Rochat (Ed.), Early social cognition: Understanding others in the first months of life. (pp.137–154). Mahwah,

Fifth, because SSC affects both partners in the dyad, it is not possible to determine whether the differences in mothers’ depressive symptoms and maternal physiological stress in the SSC and control groups are due to the effects of SSC on the mothers or on the infants. Indeed, bidirectional influences between mother and infant are likely operating. Nevertheless, the results indicate that SSC lessens mothers’ depressive feelings and reduces their physiological stress in the first postpartum weeks. Mother/infant SSC provides health benefits to mothers, in addition to the previously documented benefits to newborns’ physiological adjustment (Charpak et al., 1996; Ludington-Hoe & Swinth, 1996; Moore et al., 2007). By reducing mothers’ depressive symptoms and physiological stress, SSC facilitates mothers’ well-being and ultimately affects infants’ development by enhancing the mother/infant relationship. Unlike other interventions to reduce depressive symptoms in the postpartum months, SSC is easy to use, readily accessible, cost effective and without adverse side effects. Mother/infant SSC may be an intervention strategy to lessen depressive symptoms and anxiety, improve maternal mood, and assist the psychophysiological connection between mothers and infants, thereby enriching the lives of mothers and their children.

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