Heartburn (Gastroesophageal Reflux) In Pregnancy
Heartburn is caused by a reflux of gastric acids into the lower esophagus, usually occurring after meals or when lying down. The gastric acids irritate the esophagus, causing a burning sensation behind the sternum that may extend into the neck and face, and may be accompanied by regurgitation, nausea, and hypersalivation. Inflammation and ulceration of the esophagus may result. Up to two-thirds of women experience heartburn during pregnancy. Only rarely it is an exacerbation of preexisting disease. Symptoms may begin as early as the first trimester and cease soon after birth. Most women first experience reflux symptoms after 5 months of gestation; however, many women report the onset of symptoms only when they become very bothersome, long after the symptoms actually began. The prevalence and severity of heartburn progressively increases during pregnancy.
The exact causes(s) of reflux during pregnancy include relaxed lower esophageal tone, secondary to hormonal changes during pregnancy, particularly the influence of progesterone, and mechanical pressure of the growing uterus on the stomach which contributes to reflux of gastric acids into the esophagus. However, some studies have demonstrated that, in spite of increased intra-abdominal pressure as the uterus expands as pregnancy progresses, the high abdominal pressure and the low pressure in the esophagus are maintained by a compensatory increase in lower esophageal sphincter (LES) pressure, supporting the finding by Lind et al. that the lower esophageal sphincter pressure rose in response to abdominal compression in pregnant women without heartburn. Other possible contributing factors include an alteration in gastrointestinal transit time. For example, some studies have suggested that ineffective esophageal motility (decreased amplitude of distal esophageal contractions) is the most common motility abnormality in gastroesophageal reflux disease (GERD).
A diagnosis of heartburn in pregnancy is generally based on clinical picture. The association of other signs and symptoms is important in ruling out underlying causes: anorexia, hiatus hernia, and gastric ulcers are the more common causes in pregnancy. Other systemic illnesses of the respiratory, cardiac, or GI tract that are associated with GI irritation or substernal pain need to be taken into account when forming a diagnosis. Preeclampsia must be ruled out on a pregnant woman in her third trimester complaining of epigastric or right upper quadrant abdominal discomfort.
Conventional Treatment Approaches
Medical treatment in pregnancy focuses on symptomatic relief. Complications due to reflux in pregnancy are rare because of its short duration, and thus upper endoscopy and other diagnostic tests are not typically indicated. Complications, however, can include esophagitis, bleeding, and stricture formation. Care should follow a “step-up algorithm” (start with simple and noninterventional strategies and add on as needed) beginning with lifestyle modifications and dietary changes. Antacids or sucralfate are considered the first-line drug therapies. If symptoms persist, histamine-2-receptor (H2) antagonists can be used. Proton pump inhibitors (PPIs) are reserved for women with intractable symptoms or complicated reflux disease. Promotility agents may also be used. All but omeprazole are FDA category B drugs during pregnancy. Most drugs are excreted in breast milk. Of systemic agents, only the H2 receptor antagonists, with the exception of nizatidine, are safe to use during lactation. There are limited data regarding the safety of antacids during pregnancy, and teratogenicity is a significant concern. One retrospective case controlled study in the 1960s reported a significant increase in major and minor congenital abnormalities in infants exposed to antacids during the first trimester of pregnancy.
Analysis of individual antacids has shown no such associations, and most aluminum-, magnesium-, and calcium-containing antacids are considered acceptable in normal therapeutic doses during pregnancy. One study “found a higher rate of congenital anomalies in children of women who took an antacid in the first trimester.” Side effects of antacids are diarrhea, constipation, headaches, and nausea. Compounds containing magnesium trisilicate can lead to fetal nephrolithiasis, hypotonia, respiratory distress, and cardiovascular impairment if used long-term and in high doses. Magnesium sulfate can slow or arrest labor and may cause convulsions. Magnesium-containing antacids should be avoided during the last few weeks of pregnancy. Antacids containing sodium bicarbonate should not be used during pregnancy because they can cause maternal or fetal metabolic alkalosis and fluid overload. Pregnant women receiving iron for iron deficiency anemia should be monitored carefully when antacids are used, because normal gastric acid secretions facilitate the absorption of iron, and iron and antacids should be taken at different times during the day to avoid problems. There are also little data to support the efficacy of antacids during pregnancy. According to Richter:
Medications for treating GERD are not routinely or rigorously tested in randomized, controlled trials in pregnant women because of ethical and medicolegal concerns. Most recommendations arise from case reports and cohort studies by physicians, pharmaceutical companies, or the FDA. Voluntary reporting by the manufacturers suffers from an unknown duration of follow up, absence of appropriate controls, and possible reporting bias.
Some believe that over-the-counter antacids should be avoided in pregnancy because they can lead to an excess intake of aluminum and salt and interfere with absorption of potassium, phosphorus, and calcium and drugs such as anticoagulants, salicylates, and vitamin E. One small double-blind randomized control trial in pregnancy was identified for H2-blockers. It found that 150 mg of Ranitidine taken twice daily improved symptoms over a placebo by 44% and supposedly demonstrated no risk. However, it mirrored the antacid alone group, which also had reduced symptoms of 44%.