Estimating the Dietary Intake of Breastfeeding Preterm Infants

Aim: To determine how accurately the daily prescribed feed volume (mL/day) estimates the actual intake of breastfeeding preterm infants and to characterise the volume taken during a breastfeed at differing gestational and postmenstrual ages. Methods: A cross sectional study was conducted on preterm infants born <37 weeks gestation from two Australian neonatal units. To determine the volume taken in a 24-h period infants were weighed before and after each breastfeed. This volume was added to the charted intake to determine the total intake and then compared to the prescribed feed volume. Bland Altman analyses were used to assess the level of agreement between the two methods. Results: Fifty six infants were studied on 206 breastfeeding occasions. There was a small bias (27 mLs/day) but large 95% limits of agreement (–76 to 130 mL/day). The volume taken during a single breastfeed ranged from 0 to 101 mL (median 23 mL, IQR 9 to 31 mL) and was greater in more mature infants. Conclusions: Using the prescribed feed volume to estimate total intake has limited clinical utility for the individual infant, however the relatively small bias means that it may be useful within a population or for comparison between groups in which population means are compared. There was a large variation in volume taken during a breastfeed across all gestational and postmenstrual ages.