Extraneous factors and their influences on fetal acid-base status.

The relevance of extraneous factors on fetal and neonatal respiratory gas exchange and acid-base balance must be considered when interpreting umbilical cord blood values. However, although many of these factors can alter these values to a minor degree, the clinical impact is negligible in the unstressed fetus. The more important clinical aspect of these findings is the reassurance that conditions commonly initiated through appropriate clinical endeavors, such as regional anesthesia or tocolysis, generally have no significant adverse effects on the fetus.