1. Nagler R, Spiro HM: Heartburn in late pregnancy. Manometric studies of esophageal motor function. J Clin Invest 40:954– 970, 1961
2. Castro L de P: Reflux esophagitis as the cause of heartburn in pregnancy. Am J Obstet Gynecol 98:1– 10, 1967
3. Hey VM, Crowley DJ, Ganguli PC, et al: Gastroesophageal reflux in late pregnancy. Anesthesia 32:372– 377, 1977
4. Fisher RS, Roberts GS, Grabowski CJ, et al: Altered lower esophageal sphincter function during early pregnancy. Am J Physiol 74:1233– 1237, 1978
5. Van Thiel DH, Gavaler JS, Stremple J: Lower esophageal sphincter pressure in women using sequential oral contraceptives. Gastroenterology 71:232– 234, 1976