Validity and reliability of test weighing (weighing before and after a feed) in term and preterm neonates according to a standardized validated test weighing technique in clinical practice.

Weighing before and after breastfeeding (test weighing) is a commonly used
method to estimate milk intake in neonates. There is, however, no consensus on
the reliability of this method of test weighing. Questioning the reliability of
test weighing has major consequences for the guidance of women breastfeeding
sick or premature neonates, since there are no other clinically useful methods
to estimate breastmilk intake.

This study aims to assess the degree of accuracy of test weighing in order to
determine whether or not test weighing is a useful method in clinical practice.

This study is an observational study.
Neonates who are being fed by bottle, are swaddled en weighed before and
immediately after regular feeding by a blinded investigator. The initial body
weight of the neonate, measured right before feeding, is subtracted from the
body weight of the infant after feeding. This calculation provides an estimate
of the milk intake of the neonate.
The actual amount of milk (in milligrams) drunk by the neonate, is measured
consecutively. For this purpose, the milk bottle is weighed before feeding
(measurement 1), and immediately after feeding the same bottle with the rest of
the milk is weighed again (measurement 2).
The result of measurement 2 is subtracted from the result of measurement 1.This
calculation indicates the actual amount of milk consumed in milligrams. For
this measurement, it is assumed that 1 milligram of milk equals1 milliliter of
milk.
Weighing takes place according to a standardized validated weighing method.
Before weighing the neonates, the scales, which are digital medical class III
baby scales, are calibrated according to the Dutch Metrology Act. The accuracy
of the scales is assessed by means of calibration; meaning in this case
determining the standard deviation of repeated measurements with standard
weights.

The risks associated with participation in the study may reasonably be regarded
as negligible.
The neonate is weighed in the room where it is resides during hospitalization
and the mobile baby scales are brought to the neonate. The neonate is weighed
as it is, additional dressing or undressing is not required. The infant is
placed on the scales for weighing twice: before and after feeding.
The weighing takes about 1 to 2 minutes per weighing, thus in total about 4
minutes. Each neonate can participate once in the study.