Athlone Regional Technical College, Dublin Road, Athlone, Co Westmeath, Ireland. I. W. R. Bushnell. University of Glasgov. The purpose of this study was to ...
Bn'tishlournal of Developmental Psychology (1996), 14,41-53
Printed in Great Britain
41
@ 1996 The British Psychological Society
Tactile stimulation: Short- and long-term benefits for pre-term infants A. de R6iste" Athlone Regional Technical College, Dublin Road, Athlone, C o Westmeath, Ireland
I. W. R. Bushnell University of Glasgov The purpose of this study was to assess the effects of a programme of supplemental tactile stimulation, Touching and Caressing, Tender in Caring (TAC-TIC), on a group of pre-term infants in both the short and long term. A matched subjects design was used with experimental and control infants matched o n sex, birth weight, gestation and Apgar scores. In the short term, the experimental groups are found to bottle feed and be discharged home significantly earlier than the control group. At 15 months the experimental group showed accelerated cognitive development in comparison to the control group. No significant difference was found between the groups in their motor development. The long-term result o n the cognitive measure should be considered with caution given the limitations of the study and the role of possible mediating mechanisms, such as heightened parental expectation and altered parentinfant interaction, which have yet to be examined.
Prematurity is a contributing factor in conditions such as developmental delay, cerebral palsy, epilepsy and mental retardation (Caputo & Mandell, 1970; Cohen, 1986; Holmes, Reich & Rieff, 1988) and is associated with disturbed patterns of interaction, sensory and motor deficits, poor school performance and delayed language development (Dunn, 1986; Greenberg & Crnic, 1988; Largo, Graf, Kundu, Hunziker & Molinari, 1990). Subtle and specific cognitive and behavioural deficits in attention span, task orientation and activity have also been consistently found (Field, Dempsey & Shuman, 1981; Meisels, Cross & Plunkett, 1987; Minde et al., 1989). However, the impact of prematurity on infant development has been found to be modulated by parent-infant interactions and birth order in the first 18 months and by socio-economic status (SES) and language background from 2 years on (Sigman, Cohen, Beckwith & Parmelee, 1981). In addition, as noted by Wolke (1991), such children are most vulnerable within stressful environments, such as the school and low SES homes, when no adjustments are made for their deficits. The increased number of pre-terms as a consequence of improvements in neonatal care and enhanced survival rates has heightened the need to alleviate these problems. Preterms as young as 23 weeks' gestational age with a birth weight of 500 g or more are now '$
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A. de Rbiste and I . W. R. Bushnell
considered viable (Wolke, 1991). It is these younger pre-terms who tend to have the greatest number of medical problems early on and display a greater incidence of developmental delay and significantly more problems later in childhood (Creasey, Jarvis, Myers, Markowitz & Kerkering, 1993). Research into programmes of supplemental tactile stimulation as a cost effective means of preventing such problems and enhancing pre-term development has accelerated. The underlying premise of such programmes is that the pre-terms ‘miss out’ on essential tactile stimulation due to their early departure from the womb and care in the special care baby unit (SCBU), which has been described as providing inappropriate stimulation for the pre-term’s developmental stage (Barnard & Bee, 1983). Infrequent positive tactile contact and position change, a lack of coordinated sensory experiences, constant noise and light illumination and frequent medical procedures characterize the pre-term’s care in the SCBU (Gottfried, Wallace-Lande, Sherman Brown et al., 1981; Korner, 1981; Long, Alistair, Philip et al., 1980). However, daynight light variation, noise buffering, varied positioning and self-regulations aids, e.g. finger and foot rolls, are becoming more common components of caretaking practice in SCBUs. Over recent years, programmes of supplemental tactile stimulation have also become increasingly common in SCBUs. Such programmes generally involve providing infants with additional tactile stimulation, in the form of stroking, rubbing or gentle touching movements, in a regular and systematic fashion over a period of time varying from two days to three months across studies. Many of these programmes provide tactile stimulation on a daily basis for the duration of the infant’s hospital stay with the quantity, duration and quality of tactile stimulation provided fluctuating widely across the programmes. Most programmes start as soon as possible in the SCBU, before caretaking patterns have been established or developmental delay diagnosed. Benefits such as enhanced mental and motor development (Adamson-Macedo & Werner, 1994; Field, Vega-Lahr, Goldstein & Scafidi, 1987), decreased need for ventilation (Field, 1990), increased alertness and active behaviour (Scafidi et al., 1986, 1990), accelerated weight gain and shortened hospital stay (Field et al., 1986) have been found for such programmes. Some programmes are seen to work not through arousing the infant but through pacifying him/her and by providing a predictable pattern of stimulation (Mann, Haddow, Stokes, Goodley & Rutter, 1986) but a mediating mechanism has yet to be determined. This study set out to investigate the effects of one such programme, TAC-TIC (Adamson-Macedo, 1984) upon a sample of pre-term infants, looking at the short-term measures of: ( a )age in days at removal from care in an incubator to care in a cot; (b) age in days at first all-suck feeding; and (c) age in days at discharge. These measures were chosen as they are the criteria used by medical personnel in the determination and prognosis of infant health and development within the SCBU. Age in days at removal from care in an incubator to care in a cot (cot). Pre-terms are cared for within a regulated temperature range in an incubator due to their weak
physiological status and vulnerability to hypothermia, apnoea and hypoxia. This minimizes the amount of oxygen they consume so that they have more available for the physiological processes of respiration, circulation and general homoeostasis (system
Benefits of tactile stirnulation
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regulation). The subsequent move to being cared for in a cot is understandably seen as quite a significant step, indicative of development and stability of their thermoregulatory sytem (the system which keeps the balance between heat production and loss).
Age in days atfirst all-suck feeding (suck). Sucking is an innate reflex and through it the infant acquires nutrition essential for growth and development. Pre-terms in comparison to full terms, however, have a very poor and impoverished sucking ability and so are fed by nasogastric tube. This continues until sucking improves sufficiently so that the infant can tolerate bottle feeds with little if any regurgitation. Accelerating the onset of ‘allsuck’ (all the daily feeds being from a bottle/breast) feeding is thus desirable to assist nutritional intake and the establishment of feeding as a pleasurable and interactive situation comparable to that found in healthy infants.
Age in days at discharge (discharge). The discharge of a pre-term infant to home is another major step reflecting consultant confidence in the stability and functioning of the infant’s physiological systems. The infant is now seen as coping well independently, with no need for any medical support or observation. Because length of hospitalization has been found to lead to poorer mental and physical development at 2 years of age (SanfordZeskind & Iacino, 1987), a discharge as early as possible is thus to the infant’s advantage. With the same sample of infants this study also examined the effect of TAC-TIC in the long term on infant mental and motor develoment at 15 months. The HOME Inventory (Caldwell & Bradley, 1984) was employed in this study to contol for the effect of stimulation in the home using covariate analysis with the cognitive and motor development measures. This step was taken since stimulation in the home has been found to correlate positively with both SES and cognitive development (Bradley, 1982) and to be higher in homes of pre-terms who have participated in a tactile stimulation programme (Solkoff & Matuszak, 1975). The overall experimental hypotheses of this study were that the experimental (stroked) in comparison to control (non-stroked) infants would show better mental and motor development at 15 months and would display more developmentally advanced results, i.e. younger ages, on each of the three short-term measures of age in days at removal from care in an incubator to care in a cot; age in days at first all-suck feeding; age in days at discharge.
Method
Design A matched subjects design was employed with experimental and control infants matched o n birth weight, gestation, Apgar scores at 1 and 5 minutes and gender. This was done to ensure that any effects found were not due to the better health status and prognosis associated with infants of larger birth weight, older gestational age and greater Apgar scores or to an unequal proportion of the sexes. Female infants are known to be less vulnerable to insult in early life than their male counterparts and also are more senstive to tactile stimulation, which could have an influence on the effectiveness of a tactile stimulation programme (Bell & Costello, 1964; Maccoby & Jacklin, 1974). Hospital consultants were not aware of the group status of the infants to prevent any confounding influence on the variables examined.
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Subjects The subjects were 42 pre-term infants, 30 male and 12 female, who were born before 37 weeks’ gestation with a birth weight below 2.5 kg. None suffered from any debilitating medial condition (e.g. congenitial heart defect) other than jaundice and mild respiratory distress syndrome. Thirteen of the infants (seven experimental, six control) required oxygen support via bag and mask immediately after birth and six infants (three experimental, three control) required oxygen ventilation in the form of a head box for one to 14 days. All of the infants came from Scottish families. The mean maternal age of the experimental sample was 26 years while for the control it was 30 years. Seventeen mothers (seven experimental, 10 contol) in the sample were married, 10 were cohabitating (six experimental, four control) and 15 were single (eight experimental, seven control). Looking at parity, the groups were quite similar in their distributions. Of the whole sample, 26 were first-born (live) children (12 experimental, 14 control), seven were second-born (five experimental, three control), one was third and another was fourth (control and experimental, respectively). There were missing parity data for six infants (three experimental, three control). In order to obtain parental permission, parents of the experimental infants were shown the stroking programme at the onset of the study and were made aware of its possible, though inconclusive, role in enhancing infant development. They did not carry out the stroking programme though they may have incorporated some of the movements into their own tactile interaction with the infant. Parents of control infants were asked if they agreed to have their infants followed up and assessed in the second year of life as part of a study looking into pre-term infant development. Experimental infants were initially recruited with control infants then being recruited if they matched one of the experimental infants on the criteria referred to earlier. A control infant was considered as an acceptable match to an experimental infant if he o r she was of the same sex and within + or - 0.5 kg birthweight, o r - two weeks’ gestational age and + or - 1 on their Apgar scores (+ or - 3 on Apgar at one minute for one pair).
+
Table 1. Subject characteristics Experimental
Birth weight (kg) Gestation (wks) 1 -minute Apgar 5-minute Apgar
Control
Mean
SD
Range
Mean
SD
Range
1.91 33 7.6 8.9
0.34 1.57 2.14 0.43
1.2-2.5 29-36 1-9 8-10
1.85 33 8.1 8.9
0.26 2.18 1.49 0.38
1.3-2.2 28-36 4-9 8-1 0
Long-term subjects O u t of the original 42 subjects only 26 (18 males, eight females) experimental and control infants were assessed at 15 months uncorrected age. Change of residence (N= 5), emigration (N= 2) and adoption (N= 1) accounted for attrition in the experimental sample and their matched controls were consequently dropped from the control sample. There were no significant differences between the attrition sample and the long-term sample in any of the characteristics outlined in the previous section. No loss of control subjects occurred other than those whose experimental matches were lost. Information on the SES of the partner’s occupation if the mother was married or cohabiting, or her own occupation if she was single, was collected from this sample using the HMSO Classification of Occupations (1980). Holidays and inconvenience of testing for the parents accounted for the range of age at assessment. The overall mean age at long-term assessment was 15 months and 4 days (SD = 0.9, range = 14-18
Benefits of tactile stimulation
45
months). For the experimental infants (nine males, four females) alone this was 15 months and 5 days (SD = 0.9, range = 14 months-17 months and 18 days) whereas for the control infants (nine males, four females) it was 15 months and 2 days (SD = 1.06, range = 14-18 months). The tester was the first author who was aware of the group status of the subjects. This is a methodological flaw in the study and it is explored further in the Discussion.
Table 2. Long-term infant characteristics Experimental
Birth weight (kg) Gestation (wks) 1 -minute Apgar 5-minute Apgar
Control
Mean
SD
Range
Mean
SD
Range
1.92 32.8 7.69 8.92
0.36 1.77 2.32 0.27
1.2-2.5 29-36 1-9 8-9
1.86 33.3 8.46 8.92
0.31 2.43 0.77 0.49
1.3-2.2 28-36 7-9 8-1 0
Table 3. Long-term maternal characteristicts Experimental
Parity“
SES
Control
Single
Cohab.
Married
Single
Cohab.
Married
First
Second
Third+ Unemp. 6
First
Second
Third+ Unemp. 4
1/11 3
IWIV 4
1/11 4
III/IV 5
Missing parity data for t w o mothers.
Stimulation The programme of stimulation employed was the TAC-TIC programme (Touching and Caressing, Tender in Caring; Adamson-Macedo, 1984), a systematic sequence of stroking movements across the infant’s body from head to toe. It was designed for use with hospitalized newborns who were viewed as being deprived of positive, tactile contact. TAC-TIC is currently in use in Britain and revolves around the principles of G R E C (Gentleness, Rhythm [of stroking movements], Equilibrium [of pressure] and Continuity of stroking; Adamson-Macedo & Alves-Attree, 1994). The stroking is initiated on the crown of the baby’s head and continues in a cephalocaudal direction with stroking of the baby’s temples, face, nape of the neck, chest/stomach, arms and hands, legs and feet and finally the baby’s back with a repetition of the arm and leg movements. Several movements are performed on each bodily region, e.g. the facial movements involve stroking of forehead, eye and mouth areas. All of the strokes are performed three times with the lightest of pressure using the finger-tips, acting on the skin surface rather than at a muscular level. Tactile contact is always maintained with the baby using one hand while the fingertips of the other hand stroke the baby’s skin. If the baby responds with excessive sucking, stretching or other movements, then the baby is allowed to settle again before the next stroke is initiated. The experimenter’s hands and arms were always scrubbed, warmed and disinfected immediately before conducting the procedure and hats and other items of
A . de Rbiste and I. W.R. Bushnell
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clothing were removed from the infant, along with the nappy being loosened before he o r she was stroked . This programme was chosen as it is the only known tactile stimulation programme for pre-term and low birth weight infants that is in ongoing practice in Britain. The approximate duration of the procedure for each infant was 20 minutes and it was performed once daily in the late morning or afternoon with each of the experimental infants from the second or third day after birth until the day prior to the day of discharge (mean duration = 17 days). A precise outline of the stroking programme is available from the authors upon request.
Equipment Bayley Scales. Infant mental and motor development were assessed using the Bayley Scales of Infant Development (Bayley, 1969) yielding MDI (Mental Development Index) and PDI (Motor Development Index) scores. The Kohen-Raz (1967) subscales of the Bayley Mental scale were also employed to analyse the Bayley Mental scale yielding five scores on: (a) Eye-hand coordination: This measures the coordination of prehension and vision which Piaget (1952) saw as underlying his third stage of mental development.
(b) Manipulation: This taps well-aimed motor coordination and motor activity for its own sake which Piaget (1952) saw as underlying his third stage of mental development. (c) Object relations: This pertains to activities intended to come into touch with objects out of reach or sight and such activities are seen by Piaget (1952) to be basic processes underlying his fourth and fifth stages of mental development. (d) Imitation-comprehension: This measures verbal understanding and graphic imitation with the premise that the understanding of spoken language is related to imitative motor activity (KohenRaz, 1967). (e) Vocalization-social contact-active vocabulary: Expressive movements and verbal utterances are measured by this scale with the premise the expression of emotional needs by. gestures and verbal _ utterances is a fundamental precedent for intentional and more objective language use (Kohen-Raz, 1967).
HOME Inventory. Stimulation in the home environment was assessed using the H O M E Inventory (Caldwell & Bradley, 1978, 1984) and incorporated within covariate analyses during data analysis to control for its effects. The H O M E Inventory was chosen as it represents a more accurate and informative measure of the influence of SES upon the child's development than SES itself (see Table 4).
Results The data (see Table 4), as expected, show that the stroked infants exhibit the more developmentally advanced results (in terms of earlier ages) on the dependent variables of suck (age in days at first all-suck feeding) and discharge (age in days at discharge).
Table 4. Mean data Experimental
Suck" cot
Discharge a
Control
Group
Mean
SD
Range
Mean
SD
Range
t
d.f.
ps
14.10
7.09 7.99 8.69
4-33 3-30 7-44
21.70 09.95 25.09
16.74 10.28 18.28
4-50 3-31 6-59
2.11 0.57 1.84
19 20 20
.05 .28 .05
09.28 19.85
Suck data missing for two subjects as they had sucked all their feeds from birth.
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Short-term data
Statistical significance was calculated using matched subjects one-tailed t tests with the TAC-TIC stroking being the between-subjects variable. The analysis revealed statistically significant differences between the experimental (stroked) and control (nonstroked) infants on suck and discharge but not on cot (age in days at removal from care within an incubator to care in a cot).
Long-term data Infant development. As can be seen from the data in Table 5, the experimental and control groups show large differences in some aspects of their mental development but little difference in their motor development scores. The broad range of scores in both groups may be due to both groups being tested at their uncorrected ages rather than their corrected ages. They were not tested at their corrected ages because there was no comparison full-term group.
Table 5. Long-term data Experimental
Control
SD
SD
Mean MDI Coordination Manipulation Object relations Imitation Vocalization PDI
104 5.5 2.6 4.7 4.6 4.2 101
Range Mean
15.7 84-130 1.05 2-3 0.48 4-5 0.43 3-6 1.10 2 - 6 1.42 3-5 13.2 79-118
88 5.2 2.5 4.6 3.6 3.0 99
Group Range
18.9 78-120 0.83 2-3 0.51 3-5 0.65 2-6 1.32 1-5 1.18 3 4 15.8 85-122
t
d.f.
p
