While nausea is more common in the first trimester of pregnancy, it can also occur in the third trimester. Nausea in late pregnancy, with or without vomiting, should be little cause for concern most of the time. However, if you have additional symptoms, you might have a more serious disorder which requires prompt attention, including immediate delivery.
What Causes Third Trimester Nausea?
There are eight main causes of third trimester nausea. Some of these are inconvenient and others are quite serious. It can range from a recurrence of morning sickness or the more common heartburn from a growing belly to disorders like appendicitis or preeclampsia. Make a list of your symptoms and compare them to the conditions described. If you find a potential match, follow the suggestions for next steps.
1. Morning Sickness in the Third Trimester
Nausea in your third trimester could be due to recurrence of continuation of morning sickness. Although it usually disappears soon after the first trimester, some women continue to have the symptoms through to the third trimester of pregnancy. Other women are free of morning sickness during the second trimester only to have it recur in the third.
According to a monograph review by the American College of Gastroenterology (page 21):
- Decreased motility of the stomach and intestines contributes to nausea and other bowel symptoms in pregnancy. Bowel motility is even slower in the third trimester.
- The further delay in emptying of your stomach contents in the last trimester can bring back the nausea of the first trimester or worsen your ongoing morning sickness.
- It is not certain if increased pressure of the large uterus on the stomach plays a role.
The high levels of hormones during pregnancy is thought to be the cause of the slower gut motility in the third trimester.
Managing Your Symptoms
You can manage morning sickness-related nausea in the third trimester with remedies suggested for first trimester symptoms. This includes the BRAT diet (bananas, rice, applesauce, and toast), dry crackers, ginger ale, and other treatments, such as acupressure wristbands.
When to Seek Help
If you you don't get relief of your nausea from the above remedies in two days, don't hesitate to talk to your OB provider about it. This is especially important if:
- Your nausea is severe or you have vomiting
- Unable to eat or drink adequately
- Losing weight
- Lightheadedness or dizziness from dehydration
- Decreased movement of your baby
- You have other symptoms that suggest a different cause of your nausea, such as abdominal pain, headache, or decreased urine output
2. Heartburn and Indigestion
If you have heartburn, you can also feel nauseated. Heartburn occurs in 30 to 70 percent of women in pregnancy and is most common in the third trimester, according to Maternal, Fetal, and Neonatal Physiology: A Clinical Perspective (page 426).
The symptoms of heartburn include burning in the chest, nausea and indigestion - usually worse after eating. Symptoms are caused by reflux of food or acidic fluid from your stomach to esophagus because of:
- Relaxation of the muscle sphincter between the two organs
- Pressure of the enlarged uterus on your stomach
Nausea and other symptoms might be more bothersome if you also have a hiatal hernia, which is more common in the third trimester and occurs in 15 to 20 percent of pregnant women.
Managing Your Symptoms
Management of your symptoms includes making the following changes:
- Avoid spicy foods.
- Decrease your caffeine intake.
- Don't eat close to bedtime.
- Elevate the head of your bed when lying.
When to Seek Help
If you don't get adequate relief of your symptoms from the above changes, consult your doctor or midwife. You might need other treatment with antacids or prescription medications, such as cimetidine, ranitidine, or omeprazole.
3. Onset of Labor
Some women experience nausea, diarrhea, and other bowel symptoms near or at the onset of labor, according to Maternity Nursing Care (page 472). Other symptoms or signs will help you figure out if this is the likely cause of your nausea, including:
- Breaking of your waters
- Uterine contractions and backache
- Pelvic pressure
If you think you are in labor, contact your doctor or midwife or go to your hospital. Keep in mind that if you have steady belly pain that do not feel like contractions, there might be a different explanation for your nausea.
4. Appendicitis in Late Pregnancy
Nausea and vomiting are common symptoms of appendicitis, which can occur throughout pregnancy, including during the third trimester. According to a 2008 Global Library of Women's Medicine (GLOWN) review, "Gastrointestinal Complications in Pregnancy," appendicitis occurs in 1 in 1000 pregnancies.
In addition to nausea and vomiting, symptoms include:
- Loss of appetite
- Abdominal pain
In the third trimester, your abdominal pain and tenderness might be located in the right upper instead of your lower abdomen, making firm diagnosis difficult.
Management and Complications
Don't delay seeing your doctor if you have the above combination of symptoms. Prompt diagnosis and treatment of appendicitis is important to reduce your risk of complications. Ultrasound is the diagnostic imaging study of choice.
The GLOWN review notes that removal of an infected appendix is the most common surgery done in pregnancy for non-obstetrics reasons. A delay in diagnosis and rupture of the appendix before surgery increases the risk of maternal mortality from 5 percent to 20 percent. The fetal mortality rate increases from 4 percent to at least 30 percent.
5. Preeclampsia of Pregnancy
The Mayo Clinic lists nausea or vomiting among the symptoms and signs of preeclampsia of pregnancy. Preeclampsia is a serious disorder that develops in some pregnant women who have high blood pressure. It usually begins after 20 weeks of pregnancy but is most common in the third trimester.
Early signs of preeclampsia include swelling in your extremities and protein in your urine. If you develop nausea or vomiting in the third trimester and have any of the following additional symptoms, contact your doctor immediately:
- Facial swelling, especially around your eyes (periorbital edema)
- Abdominal pain, especially in the right side of your upper abdomen (right upper quadrant)
- Severe headaches and sudden changes in your vision
- Decreased urine output
These symptoms indicate worsening of the condition and an increased risk to you and your baby, including death.
Preeclampsia can lead to full blown eclampsia (seizures), increasing the risk of:
- Liver and kidney failure
- Blood clots and fluid in your lungs
- Stroke and coma
Severe preeclampsia/eclampsia can rapidly lead to death of you and your baby. Prompt delivery is vital to decrease the chance of these outcomes.
6. The HELLP Syndrome
Nausea, which can be accompanied by vomiting, occurs as a symptom in the HELLP syndrome (hemolysis, elevated liver enzymes, low platelet count), one of several liver disorders of the third trimester of pregnancy. These conditions of the liver can have severe adverse effects on your baby and you.
According to the American College of Gastroenterology (ACG) monograph cited at the top of the article (page 38), the HELLP syndrome occurs in about 0.1 percent of pregnancies but the incidence increases to 10 percent in pregnant women with preeclampsia.
Symptoms and Signs
In addition to nausea/vomiting, early symptoms and signs of the HELLP syndrome can include:
- Mid upper abdominal pain
- Tenderness over your liver
- High blood pressure
If you have the HELLP syndrome, your blood tests will show evidence of breakdown of red blood cells (hemolysis), high liver enzymes, and decreased platelet count.
Don't hesitate to go to the hospital if you have the above symptoms with your nausea. You and your baby are at risk for significant complications depending on the severity of your symptoms and lab results:
- You are at risk for extreme high blood pressure and seizures (eclampsia), renal failure, and problem clotting your blood.
- There is a small risk for rupture of your liver with the chance the death of you and your baby.
- Your baby is at risk for retarded growth, premature delivery, stillbirth, or death after delivery.
The HELLP syndrome can worsen quickly overnight, so immediate delivery is essential as soon as the diagnosis is made. If your pregnancy is less than 34 weeks, your doctor might choose to give you medicines for two days to mature your baby's lungs before delivery.
7. Acute Fatty Liver of Pregnancy
Acute fatty liver of pregnancy (AFLP), caused by an accumulation of fatty acids in the liver, occurs in less than one percent of pregnancy. It occurs most frequently between 34 and 37 weeks of pregnancy according to Sleisenger and Fordtran's Gastrointestinal and Liver Disease (page 634 to 636).
A genetic deficiency in an enzyme that breaks down fatty acids in your liver and your baby's liver causes AFLP. The demands of the fetus in the third trimester can overwhelm this enzyme, leading to the increased fatty acids in your liver.
Symptoms and Signs
Accumulation of fatty acids in your liver can cause:
- Nausea and vomiting
- Mid upper abdominal (epigastric) pain
- Right-sided upper abdominal (right upper quadrant) pain
- Jaundice (yellowing of the eyes and skin) and other signs of liver failure
AFLP can increase your liver enzymes and can cause irreversible liver damage with its complications and you might need a liver transplant. You can also develop high blood pressure, renal failure, and problems clotting your blood. The disorder can also lead to death of your baby.
Call your doctor or go the hospital immediately if you have the above combination of symptoms. Prompt delivery is vital as soon as the diagnosis is made before your liver fails or your baby dies.
8. Intrahepatic Cholestasis of Pregnancy
Intrahepatic cholestasis of pregnancy (IHCP) is more common in the third trimester and occurs in less than of one percent of pregnancies, according to the above referenced ACG monograph (page 36). With IHCP, bile acids accumulate and damage your liver.
IHCP causes the following symptoms:
- Severe skin itching (the hallmark of the disorder)
- Nausea and vomiting
- Abdominal pain and jaundice
Your liver enzyme, alkaline phosphatase, and your bile acids will be elevated on blood testing.
The disorder is rarely as harmful to you as AFLP, but the itching can be unbearable. You will get relief of your symptoms within a day or two of delivery. IHCP can be more harmful to your baby than to you. Adverse effects on your baby include an increased risk of preterm delivery, passage of meconium, and stillbirth.
See your doctor as soon as possible if you have the above symptoms. Because of the risks, the recommendation is prompt delivery if you are at term, or, if you are less than 34 weeks and you and your baby are stable, fetal monitoring for 48 hours until the baby's lungs mature.
Overall Management Plan
Nausea in the third trimester can lead to poor intake of food and fluids. Some causes can severely affect the well-being of you and your baby. The management plan depends of the severity of your nausea, additional symptoms and the underlying cause.
- The first step is to assess the health of you and your baby.
- Next step is to control the nausea and improve intake of fluids and nutrition as needed and as appropriate to your diagnosis.
- Further steps include diagnosing the cause of the nausea to guide additional treatment options
- Other management might include surgery or plans for delivery.
Pay Attention to All Your Symptoms
Pay attention to the severity of your nausea and be aware of any other signs or symptoms that might indicate that you have a significant problem. Because some causes of nausea in the third trimester can put you and your baby at risk, don't hesitate to contact your doctor if you don't feel well.