Medical Studies Research on Premature Babies

The womb-like nature of the Amby Natures Nest Baby Hammock makes it an ideal bed not only for full term babies, but for preemies as well. Premature babies seem to thrive when they sleep in an environment that has the ingredients of the maternal womb- enclosure, tactile touch and movement.

Experiments with ‘hammock incubators’ have shown that premature babies nurtured in a hammock inside an incubator had better ‘weight gain; general maturity; auditive & visual functions and generally less agitated’.

Below are some extracts from these experiments. We thank the authors for allowing us to publish them.

Over the years there has been numerous studies on the effects of hammocks on premature (Very Low Birthweight Infants) babies. Listed below are some of the more recent ones.

Medical Research & Studies on Baby Hammocks and Premature Babies

Study No. 1

Michele Bottos, Professor. Dept of Pediatrics, University of Padova, Italy

“The effects of a ‘containing’ position in a hammock versus the supine position on the cutaneous oxygen level in premature and term babies.” November 1984.

Scope of Study:

“..we evaluated the influence of positioning and particularly a containing position in a hammock compared with the supine position, on the respiration of the newborn.”

We studied 50 babies admitted to the Neonatal Intensive Care Unit (N. I.C.U.) of the University of Padova. 33 were males ; 17 females; gestational ages were 29-40 weeks (means 33.9 weeks) and the birth weights 1060-4280 g (mean 2198.4 g). 40 babies were admitted to the N.I.C.U. as premature (less than 38 weeks of gestational age); 11 with hyaline membranes disease (HMD); 8 with perinatal asphyxia; 6 were small for gestational age (SGA); 1 had hypoglycaemia; 1 had necrotizing enterocolitis and 1 was hypotonic. 10 full term babies were admitted : 3 because of asphyxia at birth; 4 with respitory problems; 2 with non-cyanotic heart disease and 1 with severe polycythemia. 12 of the 50 babies were in the respirator at the time of transcutaneous oxygen level recording, both in the supine and the hammock position”

Summary of Findings and Assumptions

” in our opinion, one of the main points of this care is “containment”. In fact the preterm loses prematurely the containing action of the maternal utero. Probably because of this lack of holding, the so called primary dystonic phase, charaterised by the dominant influence of the Assymetrical Tonic Neck Reflux (ATNR) and the startle reaction arises so early and conditions powerfully and for a long time the neuromotor evolution of the premature newborn. These dominant reflexes overcharge the autonomic system of the neonate determining tachycardia, alterations of breathing pattern and so on; they also determine the alteration of the biological rhythms (sleep-waking; cry-still) and so delay the baby’s recovery process.

In our experience a little hammock inside the incubator gives the preterm better chances of being correctly contained: the baby maintains a more flexed position similar to the utero ; the total flexion pattern is also stimulated and can better counteract the ATRN and startle patterns which cause the onset of the dystonic phase.

In our experience all these problems may be counteracted by an incubator for newborns and especially prematures, containing a hammock. This offers the following advantages:

(1) It inhibits or at least shortens the dystonic phase, while the baby remains in a fetal position for a longer postnatal period.
(2) It facilitates bringing the hands to the middle pattern, one of the basic milestones of neuromotor development of the baby in the first year of life.
(3) By maintaining the baby’s head in the mid-line, it stimulates visual exploration of the environment.
(4) The tilted position of the hammock counteracts possible regurgitation; the risk of milk aspiration into the bronchi is therefore greatly reduced.


Study No. 2

“The Relationship Between a Regimen of Vestibular Stimulation and Developmental Behavior of Small Premature Infant”

Professor Mary Neal , University of Maryland, March 1969

Scope of Study.

” The purpose of this study was to determine the relationship between a regimen of vestibular stimulation and the developmental behavior of the premature infant as measured by 4 tests:

(1) general maturation
(2) auditory and visual response
(3) muscle tension response
(4) irritability response

These behavioral responses are representative of the most complicated behavior that can be exhibited by a neonate.

There were 62 infants studied – 31 experiment infants who received a regimen of vestibular stimulation (in an oscillating canvas hammock) which began on the fifth day of life and continued to the 251st day or 36 week total age (gestational plus living age), and 31 control infants who did not receive the regimen of stimulation.”

Summary of Findings and Assumptions.

“..After the infant was placed in the hammock and appeared comfortable, the motion pattern was initiated by turning the switch to ON. At the end of the 30 minute period, the switch was turned to OFF and the infant was removed from the hammock. The motion pattern was compound, that is, both vertical and horizontal and was designed to excite all the vestibular cells.

Among the infants studied there was no observable or recorded late edema in those infants who received a regimen of vestibular stimulation. Edema was observed and recorded on at least 7 infants in the control group.

The findings indicated that the excitation of the vestibular cells by a compound motion may have a bearing on development of the premature infant. The developmental patterns showed that muscular and neurological development of the upper extremities preceded that of the lower extremities, and that muscular and neurological development preceded that of sensory development. The experimental infant achieved statistically significantly higher scores than did the control infant in both motor and auditory-visual behavioral responses, thus supporting the premise that (this form of) vestibular stimulation enhances developmental behavior in the 28-32 week gestational age premature infant ”

Table 3.5 Vestibular Stimulation


Nature of Study

Child Characteristics


Freedman Rocking 2/day for 30 min during 7-10 daysin exp. Group E 5 pairs of twins E: temporary wt.gain
Neal Oscillating hammock3/day, for 30 min, start 5 days p.p.until 36 weeks g.a. in (E) Mean study period 4-8 weeks E: 31 infants
C: 31 infants(birth wt 800-1700gr. 28-32 weeks)
E: increased wt.gain
: better general maturity
: better auditive andvisual functions
: better Graham – Rosenblith scores
: less agitated
Korner Placed on oscillating waterbed during 7 days in exp. Group (E) Start before 6 days old E: 10 infants
C: 11 infants(birthwt 1050-1920 gr. 27-34 weeks)
E: fewer apnoeic
: no difference in vital signs, or weight gain


Study No. 3

“Effects of a Tactile Stimulation/Range-finding Programme on the Development of Very Low Birth Weight -neonates during the First Year of Life”

Prof. Paul JM Helders, Wilhelmina Children’s Hospital, Utrecht, The Netherlands, June 1988.

Scope of Study

“..To investigate long term effects of a hospital based neonatal intervention programme, we performed a follow-up study on the development of Very Low Birth Weight neonates who were subjected to a tactile stimulation/range finding programme. At corrected ages up to one year we evaluated weight-for-length gain, length, head circumference, psychomotor development, ankle mobility, tactile responses, motor behavior and physical/neurological status.”

The subjects were 67 experimental and 82 control infants (n=149) with a gestational age of 32 weeks or less and/or birth weight of less than 1500 g.

During 1984 and 1985, from admission to the intermediate care nursery until discharge, healthy Very Low Birth Weight (VLBW) neonates were subjected to a tactile stimulation/range finding programme mimicking the spatial limitation as it occurs near the end of gestation. Infants in the experimental group, when in supine position were nursed in a hammock. Control infants were nursed in the usual way, on sheep skin in alternating positions. To investigate the long term effects of this programme the experimental and control infants were subjected to a follow up study at corrected ages up to 1 year.

Summary of Findings and Assumptions

“Significant differences between the experimental and control group for weight-for-length at 12 months in girls and for two items of the psychomotor development profile. However, the difference as found between the groups means that the experimental group shows a more appropriate adaptive behavior for age as P90 for the items is at 13 and 29 weeks respectively. The hammock positioning in our programme is thought to the flexion-adduction posture with protracted shoulders, thus facilitating mid-line orientation”

Study No. 4

“Handling of Healthy Very Low birth Weight Infants during Their Initial Hospitalization Effects on Motor Behavior”

Prof. Paul J.M. Helders , Wilhelmina Children’s Hospital, Utrecht, The Netherlands, July 1991

Scope of Study

“The study was carried out at the high care unit of the Department of Neonatology of the Wilhelmina Children’s Hospital in premature infants with gestational age at birth of 32 weeks or less and/or a birth weight of less than 1500 grams.

We chose a non-moving position of both hammock and other means of positioning, thus excluding among other vestibular stimulation. Our program aimed to simulate the intra-uterine tactile stimulation by the inner surface of the uterus as it occurs towards the end of gestation..”

Summary of Findings and Assumptions

“..For this study a hammock was designed in which the experimental infants, when in the supine position, were nursed for three consecutive weeks. In the lateral position, they were supported by flannelette blankets. Control infants were nursed on sheepskin on alternating side position. The arrangements were made on a continuous basis , starting from the first day in the high care unit. . All items were scored in an awake behavioral state. Data showed more jerky movements in the control group, with distal movement being more fluent in the experimental group. The re-seek response was also significantly more present in the experimental group. The exp. group shows a higher muscle tone than the control group. A developmentally supportive environment appears to improve motor functioning and seems to be an important factor in preventing inappropriate inputs during a sensitive period of an infant’s development.

We have tried to imitate the spatial limitation/sensory stimulation as it occurs in utero, by the contact between fetus and uterine wall, towards the end of gestation. Infants of the exp. group , when in a supine position were nursed in a hammock which had been specially designed and constructed for the purpose.

Some investigators have tried to create a situation resembling the uterus in the incubator.

Neal designed a hammock which not only imitates the fetal position but also causes rotation and rhythmical activity comparable to the inter uterine situation . Rhythmical movements were applied from the fifth day after birth to a post-conceptual age of 36 weeks using a fractionated stimulation program. She reports a significant increase in weight gain and a more mature motor, auditory and visual function.

We have observed in our study that mimicking the intra-uterine constraints influences motor performance, the seek/re-seek behavior, the variation of hand movements, sucking behavior and muscle tone.

One of the areas of care giving they attended to was the physical distal and proximal environment of the infant. Specific aspect within this area included bedding and clothing (e.g. boundaries, swaddling, ‘nesting’, a hammock) support to maintain position and opportunity to suck. At the corrected age of one month, they found significant differences in the exp. group in motor maturation in terms of a more organized motor behavior, tone and self regulation ability, compared to the control group..”