Table 1 Measurement parameters for secondary outcomes

Duration of antibiotic use in neonatal units

measured by the mean difference of at least 1 day between the exposed and non-exposed groups, evaluated by medical prescription in medical records

reduction of at least 1 day in the time of antibiotic use in the neonatal unit for the exposed group when compared to the non-exposed group

Respiratory distress syndrome

measured by the difference in its incidence between the exposed and non-exposed groups, evaluated by recording the diagnosis of the doctor of the service, with the following parameters: presence of mechanical ventilation, signs of chronic respiratory disease, X-ray with changes and oxygen supplementation for more than 28 days to achieve PaO₂ greater than 50 mmHg

reduced incidence of bronchopulmonary dysplasia for the exposed group when compared to the unexposed group

Hyaline membrane disease

measured by the difference in its incidence between the exposed and non-exposed groups, evaluated by recording the diagnosis of the doctor of the service, taking as a parameter the presence of respiratory dysfunction in the first minutes of life, accompanied by tachypnea, groaning, sternal retractions; and X-ray with pulmonary hypo-insufflation and reticulo-granular infiltrate

reduced incidence of hyaline membrane disease for the exposed group when compared to the unexposed group

Necrotizing enterocolitis

measured by the difference in its incidence between exposed and non-exposed groups, evaluated by the medical diagnosis of the service, using the criteria of Bell et al. (1978) as of Stage II: Systemic Symptoms - Stage Signs I, mild metabolic acidosis, thrombocytopenia, altered peripheral perfusion; Gastrointestinal signs - signs of Stage I, absence of airflow sounds, palpation sensitivity, mass in the lower right quadrant; Radiologic findings - intestinal dilation, intestinal pneumatosis, air in the portal system

reduced incidence of necrotizing enterocolitis for the exposed group when compared to the unexposed group

Ventricular hemorrhage

measured by the difference in its incidence between the exposed and non-exposed groups, evaluated by the medical diagnosis of the service, characterized as an acute condition with deep coma, hypoventilation, apnea, seizure and arrest pupils, associated with transfontanellar ultrasound and classified according to Papile et al. (1978)

reduced incidence of ventricular hemorrhage for the exposed group when compared to the unexposed group

Acute renal failure

measured by the difference in its incidence between the exposed and non-exposed groups, evaluated by the medical diagnosis of the service, characterized by a sudden reduced glomerular filtration rate associated with clinical and laboratory data diagnosing the loss of renal homeostasis, besides the increased size of the organ, presence of abdominal masses or palpable bladder

reduced incidence of acute renal failure for the exposed group when compared to the unexposed group

Spontaneous intestinal perforation

measured by the difference in its incidence between the exposed and non-exposed groups, evaluated by the medical diagnosis of the service, characterized by sudden clinical deterioration with abdominal distension, bluish discoloration of the abdominal wall, hypotension and metabolic acidosis associated with abdominal radiography (flat or lateral) with the presence of free air

reduced incidence of spontaneous intestinal perforation for the exposed group when compared to the unexposed group

Patent ductus arteriosus

measured by the difference in its incidence between the exposed and non-exposed groups, evaluated by the medical diagnosis of the service, characterized by clinical signs such as heart murmur, precordial impulses, large pulses, pulse pressure increase systolic and diastolic blood pressure) in premature infants with increased need for ventilatory support associated with X-ray or electrocardiogram

reduced incidence of patent ductus arteriosus for the exposed group when compared to the unexposed group

Pneumonia

measured by the difference in its incidence between the exposed and non-exposed groups, evaluated by the medical diagnosis of the service, characterized by hemoglobin with neutropenia, immature leukocytes increase, thrombocytopenia, elevated C-reactive protein and cultures of blood, urine, fluid cerebrospinal fluid and positive pleural fluid associated with multiple radiological lesions on the chest X-ray

reduced incidence of pneumonia for the exposed group when compared to the unexposed group

Pneumothorax

measured by the difference in its incidence between the exposed and non-exposed groups, evaluated by the medical diagnosis of the service, characterized by extrapleural air identified on chest radiography or by needle puncture (thoracentesis)

reduced incidence of pneumothorax for the exposed group when compared to the unexposed group

Retinopathy of prematurity

measured by the difference in its incidence between the exposed and non-exposed groups, evaluated by the medical diagnosis of the service, according to the international classification, in the active disease stage of 1 to 5

reduced incidence of retinopathy of prematurity for the exposed group when compared to the unexposed group

Septicemia

measured by the difference in its incidence between the exposed and non-exposed groups, evaluated by the medical diagnosis of the service, characterized by the following clinical signs: thermal instability, respiratory distress, hypotonia, convulsions, irritability, lethargy, gastrointestinal manifestations, idiopathic jaundice, cutaneous pallor, signs of bleeding associated with laboratory tests with leukocytosis, leukopenia and left-sided thrombocytopenia

reduced incidence of septicemia for the exposed group when compared to the unexposed group

Monitoring of weight for age (z score)

measured by the difference in the frequencies of the international growth curve ranges for preterm infants (Intergrowth-21), between the exposed and non-exposed groups at hospital discharge

adequate growth, measured in Z score through the international growth curve for preterm (Intergrowth-21), in the exposed groups when compared to the unexposed

Time to achieve minimal enteral nutrition

measured by the difference of at least 1 day between the means of time between the exposed and non-exposed groups; the amount of daily volume of diet recorded in medical records equal to the proportion of 25 mL.kg⁻¹.day⁻¹ of milk of the mother or milk bank or standard formula for age is considered a minimum diet

reduction of at least 1 day in the average time to reach the minimum enteral nutrition for the exposed group when compared to the unexposed group

Time to reach full Enteral nutrition

measured by the difference of at least 1 day between the means of time between the exposed and non-exposed groups; the amount of daily volume of diet registered in medical records equal to the proportion of 150 mL.kg⁻¹.day^− 1 of milk of the own mother or milk bank or standard formula for age is considered minimum diet

reduction of at least 1 day in the average time to achieve full enteral nutrition for the exposed group when compared to the unexposed group

Length of stay in the neonatal unit

measured by the average difference of at least 1 day between the exposed and non-exposed groups, evaluated by record in hospital discharge records

reduction of at least 1 day in the length of stay in the neonatal unit for the exposed group when compared to the non-exposed group