Nausea and vomiting of pregnancy: Clinical sciences

Nausea and vomiting of pregnancy is a common condition occurring in the majority of pregnancies. It’s generally referred to as “morning sickness” but can actually occur at any time of the day. The exact cause is unknown, though it is thought to be due to increased human chorionic gonadotropin, or HCG for short, associated with early pregnancy, as well as the effects of estrogen and progesterone, which relax the lower esophageal sphincter and slow gastric motility. Nausea and vomiting of pregnancy has a wide spectrum of presentations, from mild symptoms to severe disease and hyperemesis gravidarum, which may even require hospitalization.

When assessing a pregnant patient who presents with a chief concern suggesting nausea and vomiting, your first step is to obtain a focused history and physical. Patients typically report nausea, vomiting, malaise, and an inability to tolerate their diet.

While obtaining history, pay attention to certain risk factors for nausea and vomiting of pregnancy, such as a history of nausea and vomiting in a prior pregnancy and a family history of nausea and vomiting during pregnancy. Additionally, you might find other risk factors like a history of migraine headaches, or motion sickness. Nausea and vomiting in pregnancy is also more likely to occur in multiple gestation like twins or triplets, and in a molar pregnancy. On a physical exam, you may find signs of dehydration, such as decreased skin turgor and dry mucous membranes.

Here’s a clinical pearl! The majority of patients with nausea and vomiting of pregnancy will have symptoms before 9 weeks of gestation. However, if your patient presents with nausea and vomiting for the first time after 9 weeks, or if they have additional signs and symptoms like fever, headache, abnormal neurologic examination, palpable goiter, or severe abdominal pain, then you should look for a more serious underlying condition.

Now, back to your patient! Based on these history and physical exam findings, you can diagnose nausea and vomiting of pregnancy. Your next step is to assess the severity of their symptoms by using a validated scale, such as the Pregnancy-Unique Quantification of Emesis and Nausea, or PUQE. This scale quantifies the episodes of nausea, vomiting, and retching or dry heaving the patient has per day, and allows you to determine your treatment pathway. This is especially important as early treatment of nausea and vomiting of pregnancy may help prevent progression to hyperemesis gravidarum.

Alright, let's talk about the severity of nausea and vomiting, starting with mild symptoms. Pregnant patients with mild nausea and vomiting are generally able to tolerate their diet and continue their daily routines without pharmacologic management. For these patients, you can start with non-pharmacological treatment like lifestyle modifications. These include dietary changes, such as eating small, frequent meals, incorporating high-protein snacks throughout the day, and avoiding spicy or fatty foods.

Next, you may also recommend switching to an iron-free prenatal vitamin, as iron is associated with worsening nausea and vomiting in pregnancy. Additionally, you can recommend ginger capsules, as well as acupuncture or acupressure wristbands, which might be beneficial for some patients. Finally, advise your patients to avoid any triggers that aggravate their symptoms, such as odors, heat, humidity, noise, and flickering lights.

Okay, now that treatment for mild nausea and vomiting is complete, let’s talk about moderate symptoms. Patients with moderate nausea and vomiting typically have persistent symptoms that require pharmacological management to help them tolerate their fluid and food intake. If this is the case, start the treatment with vitamin B6, also known as pyridoxine, alone or along with doxylamine.