The pancreatic polypeptide (PP) response to oral glucose ingestion was determined in late pregnancy and post partum in 11 normal healthy women. Glucose tolerance was significantly impaired in pregnancy compared to post partum. Fasting plasma PP concentrations were reduced in pregnancy [7.6 +/- 1.2 vs. 12.6 +/- 1.2 pmol liter-1 (mean +/0- SE); P less than 0.01]. The levels of PP increased after glucose ingestion during pregnancy as well as post partum, but the PP response was significantly impaired in gestation (integrated PP responses: 548 +/- 331 vs. 1645 +/- 347 pmol liter-1 min-1; P less than 0.01). It is concluded that in pregnancy, PP levels after an overnight fast are decreased and the PP response to glucose is diminished compared to post partum.