Early oral behaviour in preterm infants during breastfeeding: an electromyographic study

The objectives were to increase the understanding of the characteristics of oral behaviour during breastfeeding in preterm infants and to validate direct observations of infant sucking. Twenty-six infants were investigated once by simultaneous observation and surface electromyography (EMG) at 32.1-37.1 postmenstrual weeks. The orbicularis oris muscle was used for data analysis, as it provided the most distinct registrations. High correlation coefficients were observed with respect to classifications of EMG data by two raters on the number of sucks per burst (r = 0.97) and duration of sucking bursts (r = 0.99). The agreement between direct observations of sucking and EMG data was high. The median for mean number of sucks per burst was 8 (range 2-33) and for longest burst 28 (5-96) sucks. Sucks with low and very high intensity constituted a median of 14 (1-94)% and 25 (0-87)% of all sucks. The range in mean sucking frequency was 1.0-1.8 sucks s(-1). Suck duration ranged from 0.6 to 1.1 s. There was a considerable variation between infants in the extent of mouthing. No association with maturational level appeared for any of the components in oral behaviour. Conclusion: EMG data provided evidence of early sucking competence in preterm infants during breastfeeding, with wide individual variations. Surface EMG and direct observation are recommended as valid methods in the evaluation of breastfeeding behaviour in preterm infants.