Kangaroo Mother Care and the Bonding Hypothesis

PEDIATRICS Vol. 102 No. 2 August 1998, p. e17

Réjean Tessier*, Marta Cristo, Stella Velez, Marta Girón, SW; Zita Figueroa de Calume, Juan G. Ruiz-Paláez, Yves Charpak, and Nathalie Charpak

From the *School of Psychology, Laval University, Québec, Canada; ISS-World Lab, Kangaroo Mother Care Program, Clinica del Nino, Santa Fe de Bogotá, Colombia; - Clinical Epidemiology Unit, Faculty of Medicine, Javeriana University, Santa Fe de Bogotá, Colombia; and EVAL (Institut pour l'Évaluation dans le domaine Médical, Médico-social et de Santé Publique), Paris, France.


The data presented in Tables 1 and 2 show that the KMC group and the TC group were identical at the conceptional age of 41 weeks based on sociodemographic criteria and factors related to pregnancy and labor. A significant difference both in the gestational age and in the infant’s weight at birth and at eligibility was observed that had completely disappeared at the time of observations (41 weeks; Table 2). Because weight at eligibility is the most representative group difference before start of intervention, it will be used as covariate in the analyses.


A Comparison Between the KMC Group and the TC Control Group Based on Sociodemographic, Labor, and Delivery Characteristics

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A Comparison Between the KMC Group and the TC Control Group Based on Factors Related to Newborn Infants

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Two-way analysis of variance stratifying by birth weight showed that the savings in hospital stays were clearly related to weight at birth: an interaction effect (F(3480) = 4.06, P < .01) shows that the maximum saving in the KMC group was observed in infants weighing <1501 g (4.5 to 6.7 days), whereas in infants weighing >1500 g, the length of hospital stay was virtually identical in both groups (Table 3). As expected, there was no group effect in the NICU length of stay (F(1480) = 1.79, NS), which, however, increased with a decrease in birth weight (F(3480) = 22.6, P < .001).


Differences in Hospital Stay and Need of NICU Patterns from Birth to Term by Intervention Groups (KMC vs TC) and Birth Weight Categories

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Although the length of intervention (expressed by the kangaroo position in the KMC group and by time between eligibility and 41 weeks’ conceptional age in the TC group) was not related to dependent variables, it has not been used in additional analyses. Data analyses were then performed with two moderating conditions. The first was the interval between birth and eligibility, representing the period during which the mother was separated from the infant before beginning the intervention. It has been trichotomized: 1 to 2 days is the first category, including infants born in fairly good health and randomized shortly after birth. In this subgroup, infants left the hospital with their mothers and received either KMC or TC at home. A 3- to 14-day delay makes up the second category, and >14-day delay makes up the third category, representing a long separation before closer mother-infant contact.

The second moderating condition is the child’s health, measured by the duration of stay in the NICU. It is dichotomized as "yes" or "no." This second moderating variable is statistically independent of the delay between birth and eligibility (first moderating variable). Dependent variables are twofold: the first is the mother’s perception of the experience of a premature birth, and the second is the mother and child’s sensitivity to each other in a feeding situation. All statistical analyses were performed using the SPSS 7.5 for Windows.

KMC Benefits and the Timing of Intervention

The first set of analyses (multivariate analyses of variance) was computed using Groups as the independent condition and Delay Before Intervention as the moderating variable. These analyses were completed alternating with the mothers’ perception and their sensitivity as dependent variables (Table 4). The hypothesis suggests an interaction effect for length of delay and Group. Based on the Mother’s Perception of Premature Birth Questionnaire (perceptions scores) data for the 24-hour postnatal interview, no differences between the KMC group and the TC group were found - mothers in both groups reported the same general feelings about their recent experience. However, based on the 41-week (conceptional age) interview, there were some group differences (F(3479) = 5.33,P = .001). Sense of competence was particularly higher for mothers in the KMC group (F(1481) = 10.36, P = .001), and social support was perceived as lower for mothers in the KMC than for those in the TC group (F(1481) = 5.03, P = .03). No delay effect was found. However, in the stress and worry subscale, the data show an interaction effect: the longer the separation, the more stressed were mothers in the TC group (F(2481) = 3.07, P = .05). No covariate (infant’s weight at eligibility) effect was observed. The data also suggest the following: 1) The mother’s sense of competence was higher in the KMC group, regardless of timing of the intervention. However, post hoc analyses indicated that kangaroo-carrying practiced earlier (1 or 2 days) after birth modified the mothers’ sense of competence to a greater degree. 2) Mothers in the TC group felt more supported than did their KMC counterparts, and post hoc comparisons confirmed that this is particularly true when the infant remained in hospital longer. Finally, 3) the TC mothers’ feelings of stress increased with the time their infant spent in hospital, which was not the case for mothers in the KMC group.


Mother’s Perception and Mother and Child’s Observed Sensitivity by Intervention Groups (KMC vs TC) and Delay From Starting Intervention

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Using observational data as dependent variables have shown that mother’s sensitivity was higher in the KMC group (F(1481)= 3.71, P = .05). Interaction effects on the duration of the infant’s hospital stay before starting the KMC or TC intervention (Delay) also were found (Table 4). A Delay × Group effect was observed with respect to the mother’s sensitivity (F(2481) = 4.23, P = .02) and the mother’s cognitive stimulations (F(2481) = 3.18, P = .04), whereas mothers in the KMC group were more sensitive to the infant staying in hospital longer (>14 days) compared with mothers in the TC group. Finally, a slight but significant delay difference was observed, where the "3- to 14-day delay" subgroup of mothers responded more adequately to the child’s distress than did those in the other subgroups (F(2481) = 3.04, P = .05). These results show that the delay before starting the KMC or the TC intervention affects only marginally the expression of maternal sensitivity toward her infant. The type of intervention (KMC vs TC) is more likely to influence this maternal behavior, especially with longer infant hospital stay.

KMC Benefits and Infant’s Stay in the NICU Before Intervention

The second set of analyses uses the NICU as a moderating variable. This is an indicator of infant’s health status between birth and eligibility. This series of analyses aims to show the moderating effect of the infant’s relative weakness on the mothers’ perceptions and sensitivity toward her child. According to the first set of analyses, data revealed a strong Group effect, where mothers in the KMC group showed a greater sense of competence than mothers in the TC group (F(1483) = 11.02, P = .001; Table 5). However post hoc analyses reveal that the mothers’ sense of competence is modified to a greater degree when infants needed intensive care after birth. Marginally, a trend was seen in mothers whose infant needed intensive care to feel more socially supported (F(1483) = 2.61, P = .11). No interaction or covariate effect was observed.


Mother’s Perception and Mother and Child’s Observed Sensitivity by Intervention Groups (KMC vs TC) and Child’s Need of NICU at Birth

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The mothers’ sensitivity scores were not related directly to early skin-to-skin contact, but rather to the infant’s health during the inpatient period. The mothers sensitivity was generally higher when the infant had spent some time in the NICU compared with the dyads who had not (F(6478) = 2,21, P = .04). In particular, we found that in the former case, the mothers were more sensitive (F(1483) = 6.41, P = .01) and stimulated the infant more cognitively (F(1483) = 7.84, P = .005) and socioemotively (F(1483) = 8.14, P = .005), and the infants gave clearer cues (F(1483) = 5.42, P = .02) and were more responsive to their mother (F(1483) = 3.97, P = .05). Consequently, we can say that mother and child’s sensitivity to each other at 41 weeks’ gestational age was higher if the infant needed intensive care at birth. Moreover, interaction effects occur whereby the infant’s weakness affected the mothers in the TC group who stimulated more cognitively (F(1483) = 4.22, P = .04) and socioemotively (F(1483) = 4.28, P = .04) the infants that needed intensive care at birth compared with the mothers in the KMC group.

Pediatrics (ISSN 0031 4005). © 1998 by the American Academy of Pediatrics