Validity of routine clinical test weighing as a measure of the intake of breast-fed infants.

Routine clinical test weighing was carried out on 100 bottle-fed infants to assess the accuracy of the procedure; the feed intake was measured by weighing the feeding bottles before and after feeding. Test weight was found to be an unreliable indication of feed weight, underestimating the amount of feed actually taken at test weight values below 60 g, and overestimating the amount of feed taken at test weights over 60 g. The errors were largest in infants having test weights at the extremes of the range. Test weighing with clinical baby scales is an unreliable and inaccurate indication of feed intake in breast-fed infants.