Nausea is most often associated with the first trimester, but its unexpected return in the late stages can be alarming. At 37 weeks, pregnancy is considered full-term, meaning the body is in the final phase of preparation for birth. Feeling suddenly queasy during this time is common. While this nausea is frequently a benign consequence of physical and hormonal changes, it is important to understand the typical causes and when the symptom may warrant prompt medical attention.
Common Reasons for Nausea in the Third Trimester
The most frequent causes of nausea at 37 weeks are physiological, relating directly to the size of the growing baby and the ongoing influence of pregnancy hormones. The large, full-term uterus takes up significant space, physically compressing surrounding organs. This mechanical compression reduces the stomach’s capacity, meaning even a normal-sized meal can trigger uncomfortable fullness and subsequent nausea.
This physical pressure also contributes significantly to acid reflux, as the stomach is pushed upward and its valve is less effective at containing digestive acids. The resulting heartburn can easily be perceived as general stomach upset or nausea. Progesterone continues to relax smooth muscles throughout the body, slowing down the entire digestive tract in a process known as delayed gastric emptying. Food sits in the stomach longer, which increases the likelihood of discomfort and queasiness.
Hormones associated with the onset of labor also play a role in digestive upset. As the body nears delivery, there is an increase in hormones like prostaglandins, which help ripen the cervix. These same prostaglandins can cause smooth muscle contractions in the intestines, leading to digestive symptoms such as nausea or diarrhea. For some, this late-stage nausea may be a subtle sign that labor is approaching within the coming days or weeks.
Warning Signs: When Nausea Requires Immediate Medical Attention
While most third-trimester nausea is a sign of normal bodily adjustments, it is important to differentiate this from symptoms that indicate a serious condition. Nausea that is sudden, severe, or accompanied by other specific symptoms requires immediate medical attention. One serious concern is preeclampsia, characterized by high blood pressure and signs of damage to another organ system, often the liver or kidneys.
Nausea associated with preeclampsia is often accompanied by severe headaches, visual changes such as seeing spots or flashing lights, or a sudden, unexplained swelling of the face and hands. Another warning sign is pain localized in the upper right side of the abdomen, which may signal liver involvement. This upper abdominal pain, combined with nausea, is particularly concerning for a rare but serious liver and blood disorder called HELLP syndrome.
HELLP syndrome, which stands for Hemolysis (the breakdown of red blood cells), Elevated Liver enzymes, and Low Platelets, is considered a complication of severe preeclampsia. Symptoms can rapidly progress and include severe fatigue, tenderness in the liver area, or unusual bruising or bleeding. Additionally, persistent vomiting that prevents keeping fluids down presents a risk of severe dehydration. Signs of dehydration, such as not urinating for eight hours or having very dark urine, require immediate medical evaluation.
Practical Strategies for Managing Nausea
For mild nausea, several simple adjustments to diet and routine can help alleviate symptoms. Because the stomach’s capacity is reduced, eating smaller, more frequent meals is better tolerated than three large meals. Focus on bland, dry foods that are easy to digest, such as toast, crackers, or bananas, while avoiding anything spicy, fatty, or highly acidic.
It is helpful to separate fluid intake from mealtimes to prevent over-distending the compressed stomach. Sipping on water or clear, electrolyte-rich fluids throughout the day, rather than gulping them down during a meal, can maintain hydration without worsening fullness. Natural remedies like ginger (in tea, lozenges, or food) are well-known for their anti-nausea properties and are safe to use.
Positional changes can also offer relief, particularly by mitigating the effects of acid reflux. Avoid lying down immediately after eating, and remain upright for at least an hour to allow gravity to assist digestion. Elevating the head of the bed by several inches can prevent stomach acid from rising into the esophagus during the night, reducing morning nausea.