Kramer L I, Pierpont M E
J Pediatr. 1976 Feb;88(2):297-9. doi: 10.1016/s0022-3476(76)81005-0.
In this study certain features of intrauterine environment were stimulated. Preterm infants were placed on waterbeds, gently rocked, and exposed to auditory stimuli. The stimulated group exhibited significantly better growth for weight, head circumference, and biparietal diameter of the head than did the control infants. Healthy preterm infants placed on rocking waterbeds and exposed to auditory stimuli had growth characteristics comparable to fetuses during the thirty-second to the thirty-sixth week of gestation.