Nursing care
Hyperemesis Gravidarum nursing care: what to assess and what to do first
Written and reviewed by Dana Whitfield, RN, MSN · 5 min read · Updated September 2026
Short answer
Hyperemesis gravidarum is severe, persistent pregnancy vomiting that causes measurable weight loss and ketonuria, not ordinary morning sickness. It is fundamentally a fluid and electrolyte problem, so nursing priorities start with IV rehydration, correcting electrolytes, and antiemetics, with oral intake reintroduced only once vomiting is controlled.
What it is and why it happens
Hyperemesis gravidarum is diagnosed when vomiting in pregnancy is severe and persistent enough to cause more than 5 percent pre-pregnancy weight loss, dehydration, and ketonuria, typically presenting in the first trimester and sometimes extending beyond it. This separates it clearly from the nausea and occasional vomiting most pregnant patients experience, which does not cause measurable weight loss or metabolic disturbance.
The exact cause is not fully settled, but rising human chorionic gonadotropin and oestrogen levels are strongly implicated, and risk is higher with multiple gestation, molar pregnancy, and a personal or family history of hyperemesis in a prior pregnancy. Because it is a fluid and electrolyte problem at its core, the clinical picture is closer to a dehydration and starvation state than to a digestive complaint.
How it presents — what you will actually see
Vomiting is frequent, often more than three or four episodes a day, and unresponsive to the usual reassurance and dietary adjustments that settle typical morning sickness. Patients report being unable to keep down fluids as well as food, which is the detail that most reliably separates hyperemesis from ordinary nausea.
Look for signs of volume depletion: dry mucous membranes, poor skin turgor, tachycardia, hypotension, and concentrated, reduced urine output. Weight loss from baseline and ketones on urinalysis confirm the diagnosis is hyperemesis rather than a normal pregnancy symptom, and these two findings, weight and ketonuria, are the ones that should change how you triage the patient.
Nursing assessment priorities
Weigh the patient and compare against pre-pregnancy or first-visit weight; a drop of more than 5 percent is a threshold finding, not a detail to note in passing. Send urinalysis for ketones and specific gravity, and check electrolytes, since hypokalaemia and metabolic alkalosis from repeated vomiting are common and need correcting alongside rehydration.
Assess orthostatic vital signs and skin turgor to grade dehydration severity, and ask directly about fluid tolerance, not just food tolerance, since a patient who is still managing sips of water is in a different category from one who vomits everything. Screen also for psychosocial impact; hyperemesis is exhausting and frightening, and anxiety or low mood are common alongside the physical picture.
Interventions and what to do first
IV fluid replacement comes first for any patient with signs of dehydration, using isotonic crystalloid and correcting electrolyte deficits, particularly potassium, guided by lab results. Antiemetics are given early and are safe in pregnancy when appropriately selected, commonly pyridoxine with or without doxylamine as first line, escalating to ondansetron or metoclopramide if symptoms persist.
Keep the patient nil by mouth or on minimal oral intake until vomiting is controlled, then reintroduce fluids and small amounts of bland, dry food gradually, watching tolerance at each step rather than moving to a full diet at once. Thiamine supplementation is given before or alongside IV dextrose in prolonged vomiting to prevent Wernicke's encephalopathy, a step that is easy to overlook when the focus is on fluids alone.
Complications to watch for
Watch for Wernicke's encephalopathy in any patient with prolonged vomiting and poor intake who then receives dextrose without thiamine first; confusion, ataxia and eye movement abnormalities are the warning triad. Electrolyte derangement, particularly hypokalaemia, carries its own cardiac risk and needs repeat monitoring through treatment, not a single check on admission.
Severe or prolonged cases carry a risk of low birth weight and, rarely, other adverse fetal outcomes if dehydration and nutritional deficits are not corrected, so ongoing fetal wellbeing assessment runs alongside maternal treatment. Oesophageal tears from forceful vomiting, though uncommon, should be considered if the patient reports haematemesis or chest pain with vomiting episodes.
Patient teaching before discharge
Teach the patient to recognise recurring dehydration, reduced urination, dizziness, dry mouth, and to seek review promptly rather than waiting it out at home. Advise small, frequent, bland meals once oral intake resumes, cold or room-temperature foods over hot ones, and separating fluids from solid meals if vomiting recurs, mirroring the dry-meal approach used for other conditions where rapid gastric transit provokes symptoms.
Confirm the patient knows how and when antiemetics are timed relative to meals, and that stopping them early because symptoms have briefly improved often brings vomiting straight back. Make sure follow-up for weight and ketone checks is booked before discharge, since hyperemesis frequently relapses and the same thresholds, weight loss and ketonuria, are what should prompt a return visit.
The next step on this is the same as on everything else here: answer questions and read the rationales. Our maternity and newborn practice questions are the closest set to what this page covers.
Common questions
How is hyperemesis gravidarum different from normal morning sickness?
Morning sickness causes nausea and occasional vomiting without significant weight loss. Hyperemesis gravidarum causes weight loss of more than 5 percent of pre-pregnancy weight, ketonuria, and dehydration, and does not settle with the usual reassurance and dietary adjustment.
What lab finding confirms hyperemesis gravidarum rather than typical pregnancy nausea?
Ketones on urinalysis alongside documented weight loss are the key confirming findings. Electrolyte disturbance, particularly low potassium, and a raised urine specific gravity support the diagnosis of significant dehydration.
Why is thiamine given in hyperemesis gravidarum?
Prolonged vomiting with poor oral intake depletes thiamine stores. Giving IV dextrose without replacing thiamine first can precipitate Wernicke's encephalopathy, so thiamine is given before or alongside dextrose in patients with a prolonged history.
What is the first-line antiemetic in hyperemesis gravidarum?
Pyridoxine, with or without doxylamine, is typically first line and considered safe in pregnancy. Ondansetron or metoclopramide are used if symptoms persist despite first-line treatment.
When should a pregnant patient with vomiting be treated as hyperemesis rather than reassured and sent home?
When vomiting has caused measurable weight loss, ketonuria, or signs of dehydration such as tachycardia, dry mucous membranes, or reduced urine output. At that point IV rehydration and electrolyte correction take priority over dietary reassurance alone.