The Effects of Mothers’ Voice on the Long Term Development of Premature Infants: A Prospective Randomized Study

Abstract

Language acquisition appears to begin during fetal life. This is substantiated by the fact that the fetus recognizes and remembers the voice and melody of the mother's language. We hypothesized that Auditory Stimulation of preterm infants with their mothers' voice may also improve their language and overall development. 24 preterm infants were exposed on a daily basis 5 times for 30 minutes to the recorded voice of their mothers for 6 to 10 weeks beginning 1 to 3 weeks after birth. A control group of 24 infants (with comparable intensive care standards) had similar gestational age (24-30 weeks) and birth weight (650-1440g) as the treatment group. Developmental tests were done at the post-term age of 5 and 20 months (Griffiths Development Quotient), at 56 months (Columbia Mental Maturity Scales, active vocabulary; and a logopedic test of understanding) and 6 years (understanding and construct of sentences). Early developmental parameters were logged by the mothers upon discharge, through their use of a daily diary. This included assessment inquiries related to breastfeeding and mood. At 5 months of age, the Griffiths Development Quotient was significantly (p=0.007) higher in the stimulated infants (95± 15) when compared with the controls (80±20). Stimulated infants began earlier than the controls to use two-word sentences (17 vs. 20 months), in the same range than time-born infants; at 6 years the subtest "speech understanding” was significantly better in the stimulated group than in the controls (p<0.05). The mothers of the stimulated infants reported less burden and showed more stability. They breastfed their babies at 5 months after full term significantly more often as compared to controls (50% vs. 12.5%). Auditory Stimulation of preterm infants using recordings of mothers' voice appears to improve emotional stability of the mothers and development of their preterm infants. In particular, development of speech and understanding appears to improve through 6 years of postnatal age.