Pregnancy is a journey filled with many physical changes, and the final weeks often bring a new wave of symptoms as the body prepares for labor. While nausea is commonly associated with the first trimester, it can sometimes reappear as the due date approaches. This late-term queasiness is one of several signs that may indicate the biological shift toward childbirth is underway. Understanding why nausea might occur at this stage can help expectant parents interpret their body’s signals.
Nausea as a Pre-Labor Symptom
Nausea is a reported symptom for many women in the hours or days immediately preceding the onset of active labor. It is not considered a definitive sign of labor, but it often accompanies the body’s final preparations for birth. Some women may experience this nausea as a general queasiness, while others may have episodes of vomiting right before or during early labor.
This feeling is often linked to the body slowing down its digestive processes to conserve energy for the work of labor. Personal accounts suggest the symptom can appear anywhere from 24 to 48 hours before regular contractions begin. However, the absence of nausea does not mean labor is far off, as it is a highly variable experience.
Physiological Causes of Late-Term Nausea
The reappearance of nausea late in pregnancy is primarily attributed to hormonal changes and mechanical pressure within the abdomen. As the body initiates labor, it releases specific hormones that affect smooth muscle tissue throughout the body. Prostaglandins, which help soften the cervix, are one such group of hormones that can also stimulate the gastrointestinal tract, potentially causing nausea or diarrhea.
The baby’s positioning also contributes to digestive discomfort. When the baby descends deeper into the pelvis, a process known as “lightening,” pressure on the stomach and other digestive organs increases. This shift can contribute to reflux, a feeling of fullness, and nausea.
Other Common Signs of Impending Labor
Because nausea is not a reliable standalone indicator, looking for other signs offers a more complete picture of impending labor. One common sign is the “bloody show,” which is the release of the mucus plug that sealed the cervix during pregnancy. This discharge may be tinged pink, brown, or red with blood and can occur days or weeks before labor, or just as it begins.
Some women report a sudden and intense desire to clean and organize their homes, often called the “nesting instinct.” Another frequent symptom, linked to the same prostaglandin release causing nausea, is diarrhea or loose stools, as the hormones relax the smooth muscles of the bowel. Lower back pain and a feeling of increased pelvic pressure also become noticeable as the baby settles into the birth canal.
When Nausea Signals a Medical Concern
While pre-labor nausea is common, severe or persistent nausea and vomiting, especially when new in the third trimester, can signal a medical issue requiring immediate attention. A serious concern is preeclampsia, a condition characterized by high blood pressure and damage to other organ systems, most often the liver and kidneys. Nausea and vomiting are possible symptoms of preeclampsia.
A healthcare provider should be contacted immediately if nausea is accompanied by severe headache, visual changes like blurring or light sensitivity, or sharp pain in the upper right side of the abdomen. These are warning signs of severe preeclampsia or its related condition, HELLP syndrome. Additionally, vomiting that prevents keeping down fluids can lead to dehydration, which may require medical intervention.