The co-reviewer (MJA) identified studies meeting the search criteria, assessed the methodological quality of the included studies, and reviewed the text.
New trials were sought using the same search strategy and selection criteria employed in the previous review. One new trial was identified and incorporated into the review.
| Study | Methods | Participants | Interventions | Outcomes | Notes | Allocation concealment |
| Bell 1980 | Water intake was controlled by study protocol until one of six criteria was met: significant patent ductus arteriosus (PDA), dehydration, death, full enteral feedings, transfer to another hospital, or age 30 days. This was a randomized, unblinded clinical trial. Enrolled infants were divided into eight groups (prognostic stratification) according to three factors thought to influence the risk of PDA: birth weight below or above 1.25 kg, size for gestational age (AGA vs SGA), and respiratory status (presence or absence of significant RDS). Within each of the resulting eight groups, subjects were randomly assigned to either of two treatment groups ("low" and "high" volume water intake) by opening the next opaque, sealed envelope from the pile for the corresponding prognostic group; the envelope contained the designation of "low" or "high" volume group as determined from a table of random numbers prior to enrollment of the first subject in the study. Within each of the eight prognostic groups, the randomization was balanced so that the number of low and high volume infants was equal after every second infant was enrolled into that group. Consecutively enrolled infants in each group were paired for analysis. A two-sided sequential plan was used, and the outcomes for discordant pairs of infants were plotted on this plan. No confounding variables were identified. No infants were withdrawn from the study. Infants were cared for in unhumidified single-walled incubators. | The participants were 170 infants with birth weight ranging from 751 to 2000 g. They were enrolled within the first three days of life. Complete accounting is given for infants in this weight range who contemporaneously were not enrolled in the study. Infants were excluded who by the third day of life had died, were receiving more than half of their water intake enterally, had evidence of PDA or other congenital heart defect, were suspected of having renal anomaly or injury or elevated intracranial pressure, or were clinically dehydrated. Of the 384 consecutive infants admitted with birth weight between 751 and 2000 g, 123 were excluded according to one or more of the aforementioned criteria. Of the remaining 261 eligible infants, consent was not sought in 39 cases and was denied in 52 cases. The remaining 170 infants were enrolled in the study. The mean birth weight was 1.4 kg in both groups, and the mean gestational age was 31 weeks. | The subjects' total water intake (enteral plus parenteral) was determined by study protocol. An upper limit was set for the "low" volume group, and a lower limit was set for the "high" volume group. These limits depended on birth weight and varied with postnatal age and were raised by 10 ml/kg/d during phototherapy. The mean daily water intake for all subjects throughout the study was 122 ml/kg/d for the low volume group and 169 ml/kg/d for the high volume group. | The outcomes compared between the treatment groups included maximum weight loss, PDA, PDA with signs of congestive heart failure, necrotizing enterocolitis, bronchopulmonary dysplasia, and death. | The results of this study were reported in the New England Journal of Medicine (1980; 302:598-604) except for the detailed limits for water intake in all subgroups, which were published only in a letter in the Lancet (1979; 2:90). | A |
| Kavvadia 2000 | Water intake was determined by study protocol for first seven days. This was a randomized, unblinded clinical trial. | The participants were 168 infants with birth weight 1500 g or less with required assisted ventilation within 6 hours of birth. | Subjects were randomly assigned to receive one of two fluid regimens. The water intake prescribed for the infants in the restricted intake group was lower than the liberal group by 20-40 ml/kg/d. The water intake could be adjusted according to specific guidelines if an infant in either group developed renal failure, hypotension, or hyperbilirubinemia requiring phototherapy. Overall, the infants in the restricted intake group received 11% less water than the infants in the liberal group. | The outcomes compared between groups were death or survival, duration of assisted ventilation, duration of supplemental oxygen, oxygen dependence at 28 d, oxygen dependence at 36 weeks postmenstrual age, pneumothorax, pulmonary interstitial emphysema, intracranial hemorrhage, patent ductus arteriosus, necrotizing enterocolitis, renal failure, and treatment with pancuronium, inhaled nitric oxide, high-frequency ventilation, diuretic drugs, and corticosteroids. | The results of this study were reported in three papers: European Journal of Pediatrics (1999; 158:917-22), Acta Paediatrica (2000; 89:237-41), and Archives of Disease in Childhood Fetal and Neonatal Edition (2000; 83:F91-6). | B |
| Lorenz 1982 | The duration of study (control of water intake according to study criteria) was for five days after birth. This was a randomized, unblinded clinical trial. The details of randomization are not given, but the subjects were first stratified according to birthweight group (750-999 g, 1000-1249 g, and 1250-1500 g), 5-minute Apgar score (6 or less vs more than 6), presence of respiratory distress syndrome (RDS), and hospital of birth (inborn vs outborn). No confounding variables were identified in a comparison of demographic features in the two groups. Deviations from protocol were allowed for infants with patent ductus arteriosus (PDA), but the number for whom this occurred is not stated. Seven of 108 infants were withdrawn from the study. Two infants in the liberal water intake group were subsequently found to have non-PDA congenital heart defects; two in the restricted water intake group were withdrawn because of intestinal obstruction or perforation requiring surgery; and three infants in the restricted water intake group died within 24 hours of enrollment. In addition, 13 infants were excluded from analysis because they had no matching infant (according to the above stratification criteria) who received the other treatment. Infants were cared for in maximally humidified, single-walled incubators. | The participants included in the analysis were 88 AGA infants with birth weight between 750 and 1500 g. The "exclusion" criteria given in the report were actually withdrawal criteria: non-PDA congenital heart disease, conditions requiring surgery, and death within 24 hours after entry into the study. The mean birth weight in both groups was 1.2 kg, and the mean gestational age was 29 weeks. Thirty-four infants had 5-minute Apgar scores of 6 or less; 64 had RDS; and 30 infants were inborn. The gender distribution is not given. | The water intake of infants in the restricted water intake group was managed to allow a 3 to 5% loss of weight per day to a maximum of 15%. Their water intake began at 65 to 70 ml/kg/d and increased to 80 ml/kg/d by day 5. In the liberal water intake group, the water intake was managed to allow a 1 to 2% loss of weight per day to a maximum loss of 10%. The water intake in the liberal intake group began at 80 ml./kg on the first day and increased gradually to 140 ml/kg/d by day 5. The actual mean weight losses were 12.9% and 8.8% in the restricted and liberal groups, respectively. | The outcomes examined were maximum weight loss as a percentage of birth weight, water intake and urine output, sodium intake, serum sodium concentration, hypoglycemia, hyperglycemia, hyponatremia, hypernatremia, significant PDA, bronchopulmonary dysplasia, intracranial hemorrhage, necrotizing enterocolitis, dehydration, acute renal failure, and death. | The results of this study were published in two papers: Journal of Pediatrics (1982; 101:423-32) and Pediatric Cardiology (1985; 6:17-24). | B |
| Tammela 1992 | The duration of the study--i.e. determination of water intake according to study protocol--was for 28 days beginning on the day of birth. This was a randomized, unblinded clinical trial. Randomization was by ordered opening of sealed envelopes containing the assignment to "dry" or "control" group as determined from a table of random numbers. There was no prognostic stratification. No confounding variables were identified in a comparison of demographic features in the two groups. No information was given about dropouts or deviations from study protocol except to say that water intake was increased by 10 ml/kg/d for infants in either group who lost more than 5% of their body weight in a day or more than 15% in total since birth. All infants were initially cared for in incubators with 50% relative humidity. | The participants were 100 infants with birth weight below 1751 g who were admitted to the NICU during the first 24 h of life. During a two-year period, 100 of 103 consecutive eligible infants were enrolled. Two were excluded because of extreme prematurity (gestational age <24 weeks), and one was excluded because of failure to obtain parental consent. The mean birthweight in both groups was 1.3 kg, and the mean gestational age was 31 weeks. Thirty-four infants (34%) were SGA, 31% were delivered by cesarean section, 49% were males, and 91% had endotracheal tubes placed for respiratory assistance. | The subjects' total water intake (enteral plus parenteral except replacement of phlebotomy losses with transfused erythrocytes) was determined by study protocol. The "dry" group was targeted to receive 50 ml/kg on day 1, 60 ml/kg on day 2, 70 ml/kg on day 3, 80 ml/kg on day 4, 90 ml/kg on day 5, 100 ml/kg on day 6, 120 ml/kg on day 7, and 150 ml/kg thereafter. The "control" group was targeted to receive 80 ml/kg on day 1, 100 ml/kg on day 2, 120 ml/kg on day 3, 150 ml/kg on days 4 through 7, and 200 ml/kg thereafter. The volumes actually delivered varied slightly from these targets but differed highly significantly between the groups, as planned. | The outcomes compared between the treatment groups included maximum weight loss, age to recovery of birth weight, weight at 28 days (as % of birth weight), hypotension, volume of erythrocytes transfused, hypoglycemia, hyponatremia, hypernatremia, hypokalemia, hyperkalemia, need for phototherapy, patent ductus arteriosus requiring treatment, necrotizing enterocolitis, intraventricular hemorrhage, duration of assisted ventilation, duration of intubation, need for high ventilator pressures, pulmonary air leak, bronchopulmonary dysplasia, and death. | The results of this study were reported in three published papers: Acta Paediatrica (1992; 81:207-12) and two identical papers in the European Journal of Pediatrics (1992; 151:295-99 and 1992; 151:367-71). | A |
| von Stockhausen 1980 | The duration of the study--i.e. determination of water intake according to study protocol--was the first three days of life. This was a randomized, unblinded clinical trial. The subjects were randomly assigned to "low" or "high" volume of water intake for the first three days of life. The details of randomization are not given, and there was no prognostic stratification. Males outnumbered females in both groups, but the preponderance of males was greater in the low volume group (23/28 vs 17/28). The low group also had slightly higher mean birth weight (2.0 vs 1.9 kg) and gestational age (34.6 vs 34.2 weeks). No information was given about dropouts or deviations from study protocol. All infants were cared for in incubators with maximal humidity. | The participants were 56 newborn infants, most of whom were premature, all enrolled on first day of life. Five of these infants required intermittent positive-pressure ventilation, and six others required continuous positive airway pressure. No information is given on exclusion criteria. | The subjects' total intake was determined by study protocol for the first three days of life. The "low" volume group was given 60 ml/kg/d, and the "high" volume group was given 150 ml/kg/d. | The outcomes reported include death, maximum weight loss, urine volume, osmolal clearance, creatinine clearance, free water clearance, net acid excretion, sodium clearance, chloride clearance, and a number of laboratory values, including urinary osmolality, sodium, potassium, chloride, calcium, phosphate, creatinine, urea, and uric acid. Also reported were hematocrit, blood osmolality, and serum concentrations of sodium, chloride, calcium, phosphate, creatinine, urea, and bilirubin. | No information is given on the incidence of PDA, NEC, or BPD. | B |
* Bell EF, Warburton D, Stonestreet BS, Oh W. Effect of fluid administration on the development of symptomatic patent ductus arteriosus and congestive heart failure in premature infants. New England Journal of Medicine 1980;302:598-604.
Bell EF, Warburton D, Stonestreet BS, Oh W. High-volume fluid intake predisposes premature infants to necrotising enterocolitis. Lancet 1979;2:90.
Kavvadia 2000 {published data only}
Kavvadia V, Greenough A, Dimitriou G, Forsling ML. Randomized trial of two levels of fluid input in the perinatal period -- effect on fluid balance, electrolyte and metabolic disturbances in ventilated VLBW infants. Acta Paediatrica 2000;89:237-41.
Kavvadia V, Greenough A, Dimitriou G, Hooper R. Comparison of the effect of two fluid input regimens on perinatal lung function in ventilated very low birthweight infants. European Journal of Pediatrics 1999;158:917-22.
Kavvadia V, Greenough A, Dimitriou G, Hooper R. Randomised trial of fluid restriction in ventilated very low birthweight infants. Archives of Disease in Childhood Fetal Neonatal Ed 2000;83:F91-6.
Lorenz 1982 {published data only}
* Lorenz JM, Kleinman LI, Kotagal UR, Reller MD. Water balance in very low-birth-weight infants: relationship to water and sodium intake and effect on outcome. Journal of Pediatrics 1982;101:423-32.
Reller MD, Lorenz JM, Kotagal UR, Meyer RA, Kaplan S. Hemodynamically significant PDA: an echocardiographic and clinical assessment of incidence, natural history, and outcome in very low birth weight infants maintained in negative fluid balance. Pediatric Cardiology 1985;6:17-24.
Tammela 1992 {published data only}
Tammela OKT, Koivisto ME. Fluid restriction for preventing bronchopulmonary dysplasia? Reduced fluid intake during the first weeks of life improves the outcome of low-birth-weight infants. Acta Paediatrica 1992;81:207-12.
Tammela OKT, Lanning FP, Koivisto ME. The relationship of fluid restriction during the 1st month of life to the occurrence and severity of bronchopulmonary dysplasia in low birth weight infants: a 1-year radiological follow up. European Journal of Pediatrics 1992;151:295-9.
Tammela OKT, Lanning FP, Koivisto ME. The relationship of fluid restriction during the 1st month of life to the occurrence and severity of bronchopulmonary dysplasia in low birth weight infants: a 1-year radiological follow up. European Journal of Pediatrics 1992;151:367-71.
von Stockhausen 1980 {published data only}
von Stockhausen HB, Struve M. Die Auswirkungen einer stark unterschiedlichen parenteralen Flussigkeitszufuhr bei Fruh- und Neugeborenen in den ersten drei Lebenstagen. Klinische Pädiatrie 1980;192:539-46.
* indicates the primary reference for the study
Bell EF. Fluid therapy. In: Sinclair JC, Bracken MB, editor(s). Effective Care of the Newborn Infant. Oxford: Oxford University Press, 1992:59-72.
Bell EF, Acarregui M. Restricted versus liberal water intake for the prevention of morbidity and mortality in preterm infants. In: Cochrane Database of Systematic Reviews, Issue 4, 1998.
Bell EF, Acarregui MJ. Restricted versus liberal water intake for preventing morbidity and mortality in preterm infants. In: Cochrane Database of Systematic Reviews, Issue 3, 2001.
| Comparison or outcome | Studies | Participants | Statistical method | Effect size |
|---|---|---|---|---|
| 01 Restricted versus liberal water intake | ||||
| 01 Weight loss (%) | 3 | 326 | WMD (fixed), 95% CI | 1.94 [0.82, 3.07] |
| 02 Dehydration | 2 | 258 | RR (fixed), 95% CI | 2.43 [0.71, 8.28] |
| 03 Patent ductus arteriosus | 4 | 526 | RR (fixed), 95% CI | 0.52 [0.37, 0.73] |
| 04 Necrotizing enterocolitis | 4 | 526 | RR (fixed), 95% CI | 0.43 [0.21, 0.87] |
| 05 Bronchopulmonary dysplasia | 4 | 526 | RR (fixed), 95% CI | 0.85 [0.63, 1.14] |
| 06 Intracranial hemorrhage (all grades) | 3 | 356 | RR (fixed), 95% CI | 0.74 [0.48, 1.14] |
| 07 Death | 5 | 582 | RR (fixed), 95% CI | 0.81 [0.54, 1.23] |
01 Restricted versus liberal water intake
01.03 Patent ductus arteriosus
01.04 Necrotizing enterocolitis
01.05 Bronchopulmonary dysplasia
01.06 Intracranial hemorrhage (all grades)
| This review is published as a Cochrane review in The Cochrane Library, Issue 1, 2008 (see http://www.thecochranelibrary.com for information). Cochrane reviews are regularly updated as new evidence emerges and in response to feedback. The Cochrane Library should be consulted for the most recent version of the review. |
