Table 1 Variables
Variable | Collection times | Units | Rationales and notes |
|---|---|---|---|
Maternal IV fluids | - admission to birth - 6, 8 or 12 hr increments | - millilitres | - millilitres match grams for weight change calculations - match time increments to nursing shifts for reliable data collection - note that admission might be before labour (i.e. starts with induction) - measure to birth only (i.e. when cord is cut), afterwards fluids cannot affect neonate |
Maternal IV fluids | - last 2 hours (hrs) before birth | - millilitres | - fluid rebalances over time (fluid in beginning will resettle), so last hours are most significant - final IV fluids positively r/t neonatal output - not certain what timing is most significant, so our decision for two hours is an educated estimate - difficult to guess last hours, but data are important |
Maternal oral fluids | - admission to birth - 6, 8 or 12 hr increments | - millilitres | - oral amounts are often considerable (e.g. > 5000 over 12 hours) - significant when combined with IV fluids - oral amounts alone showed no correlation |
Newborn weights | - birth then every 12 hrs to 72 hrs or discharge | - weight in grams | - grams match millilitres for weight change calculations - be sure babies are weighed naked - use the same scale - ensure uniformity among scales if more than one used - may need to account for security devices |
Neonatal output | - all diapers - 12 hr increments | - weight in grams | - number of diapers is not a reliable measurement - impossible to isolate voids and stools, therefore complete weight of diaper counted as output - weight of the dry diaper must be considered in research design and not added to total weight - 12 hr increments matches the weight measurements and is best for statistical analysis (e.g. to determine if diuresis continues past 24 hrs to 36 hrs - neonates void and stool in utero and at birth before birth weight is measured..We did not try to account for such events - need to account for missed diapers (babies void when diaper is off or stool in the bathtub) |
Infant feeding | - birth to 72 hrs or discharge | - yes or no - amount of supplements in mls | - determine if baby is supplemented (yes/no) or if baby is not breastfed - outliers (++ supplements) may need to be removed when cleaning the database - need data on supplementation to determine: 1) if the sample reflects the population and 2) the percentage of weight loss is similar between the supplemented and non-supplemented groups |