Restricted versus liberal water intake for preventing morbidity and mortality in preterm infants

Most premature infants are not sufficiently mature physiologically to ingest all of their required water and nutrients orally. Therefore, premature infants rely on their caregivers to regulate their volume of water intake. Thus, the caregiver must determine the amount of water to be given each day to such infants.

The objective of this review is to examine the effects of water intake on postnatal weight loss and on the risks of dehydration, patent ductus arteriosus, necrotizing enterocolitis, bronchopulmonary dysplasia, intracranial hemorrhage, and death in premature infants.

Randomized clinical trials identified in previous versions of this review were re-examined and, in each case, retained. Additional trials were sought that compared the outcomes of interest in groups of premature infants who were given different levels of water intake according to experimental protocol. Such trials were sought in a list of trials provided by the Cochrane Neonatal Review Group, with a PubMed search, and in the authors' personal files.

Only randomized clinical trials of varying water intake in premature infants are included. The review was limited to trials that included infants whose water intake was provided mainly or entirely by intravascular infusion. Included studies reported at least one of the following outcomes: postnatal weight loss, dehydration, patent ductus arteriosus, necrotizing enterocolitis, bronchopulmonary dysplasia, intracranial hemorrhage, and death.

Standard methods of the Cochrane Collaboration were used. The studies to be included were selected by two reviewers, each of whom also assessed the methodological quality of each trial. Data were independently extracted by the reviewers, who agreed on the key details. The data were then entered into tables using RevMan 4.3.1. The adverse event rates were calculated for the restricted and liberal water intake groups for each dichotomous outcome, and the relative risk and risk difference were computed. In addition, the maximal weight loss results were recorded, and the weighted mean difference was computed. The analyses - including calculation of relative risk, risk difference, and weighted mean difference - and tests of heterogeneity were accomplished using RevMan 4.3.1 software.

The analysis of the five studies taken together indicates that restricted water intake significantly increases postnatal weight loss and significantly reduces the risks of patent ductus arteriosus and necrotizing enterocolitis. With restricted water intake, there are trends toward increased risk of dehydration and reduced risks of bronchopulmonary dysplasia, intracranial hemorrhage, and death, but these trends are not statistically significant.

Based on this analysis, the most prudent prescription for water intake to premature infants would seem to be careful restriction of water intake so that physiological needs are met without allowing significant dehydration. This practice could be expected to decrease the risks of patent ductus arteriosus and necrotizing enterocolitis without significantly increasing the risk of adverse consequences.