Amniotic fluid (AF) is a complex structure with a changing content by gestational time. AF pH can be affected by both maternal and fetal conditions such as preterm ruptures of membranes, prematurity and fetal distress. While fetal urine is the major content of AF since 20th gestational week, fetal lung liquid (FLL) also acts as a minor content. Secretion of FLL depends on chloride transport and postnatal clearance of FLL is provided by active reabsorption of sodium (Na) ions. Down-regulation of epithelial Na channels (ENaCs) and an increase of pulmonary compliance accompany to pulmonary adaptation developing at the first hours of life. Lower genomic expression of Na channels in airways is shown to be associated to respiratory distress syndrome (RDS) in preterm. Although pH and electrolyte value of AF is thought to be relevant to fetal and maternal conditions such as gestational age, antenatal steroids and preterm birth, there is no study about this topic in the literature.

Inclusion Criteria:

Accepted to participate with informed consent Normal healthy pregnancies

Exclusion Criteria:

Congenital abnormalities Chromosomal abnormalities Blood contaminated AF Declined to participate