Third Trimester Sickness: What’s Normal & Not

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Is third trimester sickness normal?

Everyone knows to expect nausea early on but you might be wondering why you’re feeling sick again so late into pregnancy.

In this guide, you’ll learn the common causes of third trimester sickness and what you can do.

Third Trimester Sickness

At the beginning of pregnancy, you expect to feel sick as morning sickness sets in and causes the occasional bout of nausea or vomiting. But as you reach your third trimester, you might be wondering what’s causing your nausea.

Fewer people experience nausea in the third trimester. According to one study on 120 women in their third trimester:

  • 60% experienced heartburn
  • 16% experienced nausea
  • 7% experienced vomiting

According to the authors, these occasional periods of nausea and vomiting usually didn’t continue for longer periods. They also suggested that the women’s sickness likely has multiple causes.

Although infrequent nausea and vomiting usually aren’t a cause for concern in the third trimester, if you experience frequent sickness or nausea that doesn’t let up, you should seek medical care.

Is Third Trimester Sickness Caused by a Virus?

If you’re wondering what’s causing your third trimester sickness or nausea, first make sure you don’t have a virus. Although the typical common cold doesn’t cause nausea, you may have a stomach bug.

Symptoms of a stomach flu—or viral gastroenteritis—include:

  • Nausea
  • Vomiting
  • Stomach cramps or pain
  • Diarrhea
  • Muscle aches
  • Headache
  • Fever

Stomach bugs typically run their course and go away in a few days without treatment. However, if you have a fever during pregnancy, you should contact your doctor or seek medical attention. Fevers must be monitored because a high fever is associated with negative birth outcomes, like preterm birth and fetal abnormalities.

Is Third Trimester Sickness Caused by Food Poisoning?

Third trimester sickness can also be caused by food poisoning, like salmonella or E. coli. During pregnancy, your immune system is weakened, making you more susceptible to viruses. Along with making it easier to get sick from food contaminated with bacteria, pregnancy also makes it more likely that you’ll get more sick. For example, your non-pregnant partner might experience a little nausea from food poisoning while you may be sick to your stomach and vomiting.

Symptoms of food poisoning include:

  • Nausea
  • Vomiting
  • Diarrhea
  • Stomach cramps and pain
  • Aching muscles
  • Chills
  • Loss of appetite and energy
  • Fever

You should seek medical attention if you believe you have food poisoning during pregnancy. Later in pregnancy, food poisoning can cause preterm birth, stillbirth or a baby born ill.

Third Trimester Sickness: Causes

Before investigating the cause of your third trimester sickness, first make sure it isn’t caused by a virus or food poisoning, as discussed above. Below are the other common causes of nausea in the third trimester.

Slower Digestion

One of the most common causes of feeling sick in the third trimester is digestion issues. Your digestion slows down during pregnancy, which can leave you feeling gassy, bloated and sometimes constipated. 

Constipation is a common cause. As food stays in your stomach longer, it can cause you to feel sick. When stools don’t exit the colon soon enough, they can lead to the production of methane, which also causes nausea.

Usually, this nausea will pass and your digestion will improve. If your nausea continues, you should contact your doctor. Nausea caused by digestion that persists could be a sign of gastritis. Persistent digestion issues should also be reported to your doctor. 


Hormones are the reason why you have morning sickness early on in pregnancy and they can also contribute to your sickness in the third trimester. Estrogen levels peak in the third trimester. Some research suggests that estrogen may play a role in nausea and vomiting during pregnancy.

Prenatal Vitamin

Surprisingly, your prenatal vitamin may also be causing third trimester sickness. This is especially a cause to consider if you’ve recently switched your vitamin.

Many prenatal vitamins contain higher amounts of iron. Although iron is necessary during pregnancy, it can cause all sorts of stomach issues, from stomach pain to constipation. This usually happens when you’re changing from a low to high iron intake.

If you believe your prenatal vitamin is causing third trimester sickness, ask your doctor for recommendations that are easier on your stomach.

New cravings

Are your cravings leading you to eat something in the third trimester that you didn’t before? If so, consider whether that could be causing stomach sickness. For example, perhaps you’re eating spicy food after avoiding it for months. With your digestion system working slower, your body may be especially sensitive to certain foods.


Although less common, stress can cause nausea. This may be a cause to consider if you suffer from anxiety or if your nerves are peaking as you reach labor. Anxiety nausea can come as a random surge when you’re experiencing a moment of high anxiety. Some people may even vomit or dry heave.

Anxiety and depression are believed to affect between 20-40% of pregnant people. If you believe anxiety is causing your nausea, talk to your doctor or find a therapist you trust.

Third Trimester Sickness Remedies

The appropriate remedy for your third trimester sickness depends on the cause. Most commonly, third trimester sickness is caused by a combination of hormones and digestion issues. Below are a few possible remedies:

  • Eat smaller meals. To keep nausea at bay, try eating smaller, more frequent meals instead of large plates. This can be easier for your stomach to handle, which is especially helpful as your digestion slows down in the third trimester.
  • Avoid trigger foods. If you’re eating any new foods in the third trimester, experiment by eliminating them from your diet. If the sickness stops, you’ve found your cause. With the digestion changes later in pregnancy, your stomach may be reacting to foods it was fine with before.
  • Use stomach-calming foods. Try the traditional stomach-calming foods to see if it helps reduce your nausea. Peppermint and ginger are go-tos. Consider them in tea form or as hard candies or suckers. 
  • Consider prenatal changes. If you believe your prenatal vitamin is causing your nausea, try an alternative. You can also experiment with taking different forms of iron that may be easier on the stomach. Ask your doctor for recommendations. You can also try taking your prenatal vitamin at a different time of the day to see if it affects your stomach less.
  • Get sleep. Sometimes you just need some rest! Consider that your body is working overtime to grow a human being! That takes a physical and mental toll and all that stress may lead to a little nausea here and there. Give yourself some extra time to relax on the couch, take naps, go to bed early and sleep in.

When to See a Doctor

Third trimester sickness usually isn’t a cause for concern. Most commonly, it’s caused by digestion, hormones or diet factors. However, third trimester nausea and sickness may also be caused by a virus. If you have a fever during pregnancy, you should seek medical attention.

You should also seek medical attention if you have frequent nausea or nausea that doesn’t let up in the third trimester. Although it usually doesn’t have symptoms, nausea can be a sign of preeclampsia, which is a serious condition of high blood pressure during pregnancy.

Whenever you are unsure of the cause of your third trimester sickness, it’s best to contact your doctor.

Summary: Third Trimester Sickness

Although most people experience nausea early on during pregnancy, some also experience it later on. Third trimester sickness usually isn’t a cause for concern. Most commonly, hormones or digestion changes are to blame. Prenatal vitamins or diet changes could also be a cause.

When you’re experiencing third trimester nausea, it’s important to make sure it’s not a virus or illness. If you have a stomach illness, monitor for a fever and report any high temperatures to your doctor. Food poisoning should also be reported to your doctor because it can lead to negative birth outcomes.

When you aren’t sure what’s causing your nausea, or if your nausea doesn’t go away, contact your doctor or seek emergency care. Although rare, nausea can be a sign of preeclampsia, which is a serious condition that requires monitoring.

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