Pregnancy poses a unique medical stress to the gastrointestinal GI tract. Many of these changes such as constipation or loose stools are normal to a certain extent.

For many women, pregnancy can be a period of vulnerability for the development of new or exacerbation of existing GI disorders.

In the gastrointestinal (GI) tract, normal physiological changes during pregnancy produce dramatic modifications. Visceral organs rearrange to accommodate uterine growth. Ovarian and placental hormone levels fluctuate, altering:

• Esophageal sphincter pressure
• GI motility
• Gallbladder contractility
• Intrahepatic bile salt transport.

In addition, immunological changes occur. These may produce adverse, beneficial, or neutral effects in the pregnant mother with regard to autoimmune and infectious disease. 

The following are some of the changes observed during pregnancy:

• Nausea and Vomiting
• Heartburn: Gastroesophageal Reflux Disease (GERD)
• Constipation
• Diarrhea
• Gallbladder symptoms and stones
• Liver problems
• Pica

Nausea and Vomiting

Nausea and vomiting, particularly in the mornings (morning sickness), are common. They may be caused by the high levels of estrogen and human chorionic gonadotropin, two hormones that help maintain the pregnancy.

Nausea and vomiting may be relieved by changing the diet or patterns of eating. For example, drinking and eating small portions frequently, eating before getting hungry, and eating bland foods (such as bouillon, consommé, rice, and pasta) may help. Eating plain soda crackers and sipping a carbonated drink may relieve nausea. Keeping crackers by the bed and eating one or two before getting up may relieve morning sickness. No drugs specifically designed to treat morning sickness are currently available. If nausea and vomiting are so intense or persistent that dehydration, weight loss, or other problems develop, a woman may need to be treated with drugs that relieve nausea (antiemetic drugs) or to be hospitalized temporarily and given fluids intravenously.

Heartburn and Belching

Heartburn and belching are common, possibly because food remains in the stomach longer and because the ringlike muscle (sphincter) at the lower end of the esophagus tends to relax, allowing the stomach's contents to flow backward into the esophagus. Several measures can help relieve heartburn:

• Eating smaller meals
• Not bending or lying flat for several hours after eating
• Avoiding caffeine, tobacco, alcohol, and aspirin and related drugs (salicylates)
• Taking liquid antacids, but not antacids that contain sodium bicarbonate because they contain so much salt (sodium)

Heartburn during the night can be relieved by the following:

• Not eating for several hours before going to bed
• Raising the head of the bed or using pillows to raise the head and shoulders
• The stomach produces less acid during pregnancy. Consequently, stomach ulcers rarely develop during pregnancy, and those that already exist often start to heal.

Constipation

As pregnancy progresses, pressure from the enlarging uterus on the rectum and the lower part of the intestine may cause constipation. Constipation may be worsened because the high level of progesterone during pregnancy slows the automatic waves of muscular contractions in the intestine, which normally move food along. Eating a high-fiber diet, drinking plenty of fluids, and exercising regularly can help prevent constipation.

Hemorrhoids

Hemorrhoids, a common problem, may result from the pressure of the enlarging uterus or from constipation. Stool softeners, an anesthetic gel, or warm soaks can be used if hemorrhoids hurt.

Pica

Pica, a craving for strange foods or nonfoods (such as starch or clay), may develop.

Excess Saliva

Occasionally, pregnant women, usually those who also have morning sickness, have excess saliva. This symptom may be distressing but is harmless.

Gallbladder Problems

Women are twice as likely to have gallstones as men and much of that has to do with pregnancy hormones.  Elevated hormones during pregnancy cause the gallbladder to function more slowly, less efficiently and is more likely to lead to gallbladder stone issues.