The obstetrician's role in reducing the risk of aspiration pneumonitis. With particular reference to the use of oral antacids.

Aspiration of gastric contents is the commonest cause of maternal anesthetic death. If the pH of the contents is below 2.5, morbidity and mortality rates are likely to be higher than if the pH is above 2.5. A study of 146 patients in labor shows that one in four patients is "at risk" to acid aspiration. No time interval between last mean and either onset of labor or delivery can guarantee an empty stomach. The use of oral antacids during labor reduces the number at risk to 1 in 35. Other methods by which the obstetrician may contribute to reducing the risk are discussed.