Nausea and vomiting during pregnancy, widely known as “morning sickness,” is medically termed Nausea Gravidarum or NVP. Despite the common name, these symptoms can occur at any time of day and typically begin around the fourth week of gestation. For most people, the intense symptoms subside as they enter the second trimester, usually resolving between the 16th and 20th week of pregnancy. It can be surprising and distressing when the queasiness makes an unexpected return later in the pregnancy.
Why Nausea Can Return Late in Pregnancy
The recurrence of nausea and occasional vomiting late in gestation is a common physiological response to two main factors: shifting hormone levels and significant mechanical pressure. Even as the levels of human chorionic gonadotropin (hCG) decline, other hormones continue to influence the digestive system. Progesterone, for instance, promotes the relaxation of smooth muscle tissue, including the gastrointestinal tract. This hormonal effect slows down the movement of food through the stomach and intestines, which can directly cause feelings of nausea.
The increasing size of the growing uterus and fetus creates substantial physical pressure on the abdominal organs. This pressure pushes the stomach upward and compresses it, reducing the available volume for food and liquid. This mechanical action, combined with the relaxing effect of progesterone on the lower esophageal sphincter, increases the likelihood of severe acid reflux, or Gastroesophageal Reflux Disease (GERD). The severe irritation of the esophagus and the delayed clearance of stomach contents strongly mimic the sensations of early-pregnancy nausea.
Distinguishing Late-Term Nausea from Other Conditions
While late-onset nausea is often a benign result of mechanical and hormonal changes, any return of symptoms in the third trimester requires medical evaluation to rule out serious complications. Nausea and vomiting, particularly when persistent, can be a symptom of conditions like preeclampsia or HELLP syndrome. These conditions require immediate medical intervention due to risks to both the pregnant person and the fetus.
Preeclampsia is a blood pressure disorder that typically develops after 20 weeks of pregnancy, often manifesting in the third trimester. Warning signs that may accompany nausea include a severe, persistent headache that does not improve with pain relief, and sudden swelling of the face or hands. Visual disturbances, such as blurred vision or light sensitivity, are also indicators that require urgent attention.
A particularly concerning symptom is pain in the upper right quadrant of the abdomen or the epigastric area, often described as under the rib cage. This localized pain, especially when paired with nausea and vomiting, can be a sign of liver involvement, which is characteristic of HELLP syndrome. HELLP is a severe variant of preeclampsia involving hemolysis (breakdown of red blood cells), elevated liver enzymes, and low platelet count. Any new-onset nausea or vomiting in the third trimester must be discussed with a healthcare provider to ensure these serious pathologies are quickly excluded.
Management and Relief Strategies
Once a healthcare provider has confirmed that the late-term nausea is not due to a serious medical condition, several management strategies can help alleviate the discomfort. Adjusting eating habits to accommodate the reduced stomach capacity is often beneficial. Eating smaller meals more frequently throughout the day prevents the stomach from becoming overly full, which mitigates the physical pressure that triggers nausea.
Avoiding specific trigger foods, such as those that are highly spicy, fatty, or acidic, can also lessen the symptoms, particularly by reducing acid reflux. To combat nighttime reflux, which can cause morning nausea, it is helpful to avoid eating within three hours of lying down and to sleep with the head of the bed slightly elevated.
Certain over-the-counter remedies can provide relief, but any medication or supplement regimen should be approved by a doctor.
Over-the-Counter Relief
Antacids containing calcium, aluminum, or magnesium are considered first-line treatments for managing the acid reflux component of the nausea. Additionally, a Vitamin B6 supplement, often combined with the antihistamine doxylamine, is a common and safe treatment option for persistent nausea during pregnancy.