They found no significant differences in reflux according to age, but they did find that women had less physiologic reflux than men. A smaller study by Fass et al 3 found that normal females had significantly less esophageal acid exposure than males. In 24-hour pH studies on symptomatic patients with GERD, Ter and colleagues 12 found that men with symptoms of GERD had significantly more reflux than a similar population of female patients. Since females have significantly less reflux than their male counterparts in both normal and symptomatic patients, the current 24-hour pH upper limit of normal for pH monitoring may result in underdiagnosis of GERD in females. Endoscopic studies of the prevalence of GERD by sex are lacking.
Controversy also exists regarding the effect of sex hormones on esophageal muscle function.
LES pressure has been reported to be reduced during the luteal phase of the menstrual cycle and when a progesterone-type agent is administered. The researchers concluded that the progressive rise in plasma progesterone alone or in combination with estrogens that occurs during the course of pregnancy might be responsible for the increased incidence of heartburn in pregnant women. However, other investigators found the menstrual cycle to have no effect on the LES pressure, distal contraction, or esophageal emptying of liquid or solid boluses. It is well-known that there is an increased frequency of heartburn in pregnant females, compared with other adults. For most women, the symptoms are greatly reduced or absent after delivery.