The lungs of the fetus are filled with fluid and it is essential that fetal lung fluid is cleared at birth. This process is mediated through the activation of airway epithelial sodium channels (ENaC). In animals, ENaC is considered crucial for postnatal pulmonary adaptation. In humans, postnatal ENaC expression is dependent on gestational age and its activity, measured as nasal potential difference, correlates with lung compliance. Therefore, in the human newborn infant ENaC may be important for physiologic postnatal adaptation. The activity of ENaC is increased by beta-agonists, such as salbutamol. We hypothesize that low pulmonary expression or activity of ENaC in the perinatal period causes delayed clearance of lung fluid and thereby contributes to the risk for development of transient tachypnea of the newborn (TTN) in term infants born by Caesarean section (CS).

We hypothesize that low pulmonary expression or activity of ENaC in the perinatal period causes delayed clearance of lung fluid and thereby contributes to the risk for development of transient tachypnea of the newborn (TTN) in term infants born by Caesarean section (CS). The aim of this study is to evaluate whether the respiratory status, measured by a transthoracic ultrasound method and lung compliance, of newborns infants born by CS can be improved by inhaled salbutamol at 30-60 minutes of age. 62 infants will be included and randomized to receive salbutamol or placebo-inhalations in a double-blind manner.

Inclusion Criteria:

• healthy singleton pregnancy
• Cesarean section at 37 + 0 to 41 + 6 gestational weeks

Exclusion Criteria:

• clinically significant congenital malformations
• birth weight < 2000 grams
• intubation
• 200 bp for more than 5 min
• relevant medication of the mother, e.g. albetol, beta-agonists (e.g. salbutamol, salmeterol), corticosteroids
• the suspicion of/confirmed pneumothorax or infection