Hyperemesis Gravidarum (HG) and Nausea and Vomiting in Pregnancy (NVP)
Hyperemesis gravidarum (HG) and the broader spectrum of nausea and vomiting in pregnancy (NVP) are frequent presentations to emergency and early‑pregnancy services. This section focuses on practical ED assessment, initial resuscitation, safe prescribing, admission triggers and escalation relevant to emergency clinicians (NICE NG201).
Definition and scope
- NVP ranges from mild, self‑limited “morning sickness” to severe disease.
- Hyperemesis gravidarum describes the severe end of the spectrum and is usually considered when vomiting causes any of the following:
- inability to maintain oral intake with persistent vomiting,
- ≥5% loss of pre‑pregnancy weight,
- dehydration, ketonuria or electrolyte disturbance requiring medical therapy or monitoring.
- Incidence of HG is low (~0.3-3.6% of pregnancies) but morbidity and need for specialist care make early recognition important (NICE NG201).
Pathophysiology (concise)
- Multifactorial mechanisms:
- high hCG levels (worse with molar or multiple pregnancy),
- rising oestrogen,
- progesterone‑related delayed gastric emptying,
- heightened olfactory sensitivity,
- genetic predisposition,
- possible association with Helicobacter pylori.
- Exact mechanisms are not fully established.