What happens in the second trimester?

Many significant changes occur in your growing fetus throughout the second trimester of pregnancy. It’s also during this exciting phase that you’re able to learn your baby’s sex and morning sickness begins to fade.

As your baby is growing, your body is rapidly changing. These changes may include digestive issues such as constipation, gas, and heartburn. Learn more about these common symptoms and how to find relief so you can get back to enjoying your pregnancy.

Digestive issues and pregnancy

The digestive system is a complex network of organs that work together to help your body break down food and absorb nutrients. It includes your:

  • esophagus
  • stomach
  • liver
  • small intestine
  • mouth
  • anus

Nutrient absorption is always important for creating overall energy and cellular function, but these roles are even more crucial in supporting a growing fetus.

Digestive issues occur in pregnancy because of an influx in hormones that relax muscles in the digestive tract. Natural weight gain from supporting your baby can also put additional pressure on the digestive tract.


Constipation is a common symptom during pregnancy, and it’s more prevalent during the second trimester. The American College of Obstetricians and Gynecologists (ACOG) defines constipation as having fewer than three bowel movements per week.

Hormone levels can affect digestion beyond slowing down bowel movements. Bowel movements might be painful or difficult, and your belly might swell.

You may also have higher levels of iron if you’re taking prenatal vitamins. High iron levels can contribute to constipation.

Dietary changes are the most practical way to treat constipation during pregnancy. They’re also the safest way. Natural fiber intake can offset constipation problems. The UCSF Medical Center recommends between 20 and 35 grams of fiber per day.

Plant sources are your key to fiber, so make sure to eat plenty of fresh produce, whole grains, beans, and legumes.

Make sure you also:

As a last resort, your doctor might recommend a laxative or fiber supplement to soften and ease your bowel movements. Never take these without checking with your doctor first. Diarrhea is a common side effect of these products, which can lead to dehydration and cause complications during pregnancy.


A slower digestive system during the second trimester can lead to gas buildup that causes:

You can’t change the way your digestive system works during pregnancy, but you can help speed it up by avoiding trigger foods that lead to gas. Consider cutting down on:

  • carbonated beverages
  • dairy products
  • cruciferous veggies such as broccoli, cabbage, and cauliflower
  • garlic
  • spinach
  • potatoes
  • beans and other high-fiber foods, which you should cut only if you don’t have problems with constipation

The way you eat can also make gas worse. Try eating smaller meals and eating slowly to avoid swallowing air. If changing your eating habits doesn’t help, talk to your doctor about adding over-the-counter (OTC) gas relief products. Don’t take any supplements or herbs without checking with a doctor first.


Heartburn occurs when stomach acids leak back into the esophagus. Also called acid reflux, heartburn actually doesn’t affect the heart. Instead, you might feel an uncomfortable burning sensation in your throat and chest shortly after you eat.

Many foods can contribute to heartburn. Even if you didn’t experience acid reflux before pregnancy, you might consider avoiding:

  • greasy, fatty, and fried foods
  • spicy foods
  • garlic
  • onions
  • caffeine

Eating large meals and eating before lying down can also lead to heartburn. Elevate your pillow during bedtime to help prevent heartburn at night. Call your doctor if you have heartburn frequently, at least twice per week. They may recommend OTC antacids for relief.

When to see a doctor

Mild digestive disruptions are normal during the second trimester, but a few symptoms can raise red flags. Call your doctor right away if you experience:

  • severe diarrhea
  • diarrhea that lasts longer than two days
  • black or bloody stools
  • severe abdominal pain or belly cramps
  • gas-related pain that comes and goes every few minutes; these could actually be labor pains


Your body goes through many changes during pregnancy, and some of these changes can be unpleasant. Related symptoms such as digestive ailments will get better after labor. Be sure to discuss any concerns or severe symptoms with your doctor.