Notes on Antiemetic Use, Hyperemesis Gravidarum, and Related Prescribing Considerations (NZ Context) MIDW702ALL - T 3.5 Anti emetics

Nausea and Vomiting in Pregnancy: Antiemetics, Hyperemesis Gravidarum, and Related Prescribing Considerations (NZ Context)

• Learning aims and practice foundations

  • Work in partnership and culturally safe ways for prescribing in pregnancy (nausea, vomiting, reflux) and related care.
  • Apply midwifery practice reasoning and practice standards when choosing interventions and communicating with patients.
  • Use NZ formulary resources, Medsafe guidance, and professional consensus statements when making prescribing decisions, including complementary or alternative therapies.
  • Reassess history and prior care to ensure a complete picture before prescribing; ensure informed consent.
  • Understand scope of practice evolution; know when to refer and involve obstetric/medical teams.
  • Use evidence-based resources (Soma's position statements, Hyperemesis pregnancy pathways, NZ Formulary guidance).

• Definitions and scope

  • Nausea and vomiting in pregnancy (NVP) is common and often mild; most cases are manageable.
  • Hyperemesis gravidarum (HG) is a more severe form with persistent vomiting, risk of dehydration, electrolyte imbalance, and potential malnutrition.
  • Prevalence and risk factors discussed below.

• Key prevalence and timing data (for quick recall)

  • NVP affects roughly 60 ext{–}70 ext{%} of pregnant people.
  • HG occurs in about 1 ext{–}2 ext{%} of pregnancies.
  • HG typically begins in early pregnancy, often from $4 ext{–}8$ weeks gestation, may persist to $14 ext{–}16$ weeks, and can extend to $20$ weeks in some cases.
  • If HG is severe and untreated, there is a risk of dehydration, electrolyte imbalance, and potential malnutrition.
  • HG is recognised as a risk factor for venous thrombosis due to dehydration and hemoconcentration; cases of venous thromboembolism reported in the literature.
  • Prior HG is a risk factor for recurrence in subsequent pregnancies.
  • Adverse outcomes include weight loss, dehydration, electrolyte disturbances, and potential complications requiring admission for IV fluids and thromboprophylaxis in severe cases.

• Signs, symptoms, and how to assess (history and exam focus)

  • Collect comprehensive history: onset, duration, trajectory of symptoms, prior HG, nutritional intake, fluid tolerance, and weight loss.
  • Assess hydration status and vital signs: temperature, pulse, blood pressure, respiratory rate.
  • Review past medical history: thyroid disease (thyrotoxicosis or hypothyroidism), diabetes, psychiatric history, GI disorders, Helicobacter pylori history, asthma.
  • Evaluate red flags: shortness of breath, severe dehydration, persistent vomiting with inability to keep fluids down, rapid weight loss, dehydration signs.
  • History of previous admissions for HG increases risk of recurrence and guides urgency of management.
  • Medication history and current therapies (folic acid, iodine supplementation, any antiemetics used previously).

• Diagnostic considerations and investigations

  • Baseline labs commonly recommended after initial assessment and when active management is planned:
  • Full blood count (FBC)
  • Liver function tests (LFTs)
  • Electrolytes (Na+, K+)
  • Uric acid
  • Urinary analysis (MSU) and assessment for ketones in urine
  • When to repeat or escalate testing:
  • If dehydration persists or symptoms worsen or fail to improve with initial management, repeat investigations may be needed within 24–48 hours if awaiting community results.
  • When to involve obstetric team early:
  • If there are red flags or if management requires escalation (IV fluids, admission, thromboprophylaxis), a phone or formal referral to obstetric team is advised.
  • Monitoring and follow-up:
  • Continuous reassessment of hydration, tolerance to oral intake, and weight.
  • Dietitian input if weight loss or poor intake persists.

• Management framework and decision-making

  • Core questions before prescribing:
  • Has there been a full reassessment of the history and current presentation?
  • Is the intervention within scope of practice? If not, seek involvement of obstetric/medical teams.
  • Are medications explained and consent obtained for informed decision-making?
  • When to prescribe vs when to refer:
  • In community settings, midwives may use antiperseptives and antiemetics where appropriate, but complex HG often requires hospital-based management.
  • For severe HG or dehydration, refer to obstetric team and consider admission for IV fluids and closer monitoring.
  • Documentation and communication:
  • Use a structured handover (EspA-type tool) to convey the patient’s status, tests, and plan clearly to receiving clinicians.
  • Ensure timely communication with the obstetric team and, in rural settings, involve the patient’s GP as needed.
  • Key reference resources:
  • New Zealand Formulary (NZF) for dosing, subsidisation, and guidelines on what should be prescribed.
  • Medsafe information; understand which guidance applies in maternity vs general practice contexts.
  • Soma’s pathway for hyperemesis and nausea and vomiting; Soma’s position statements on nausea and vomiting in pregnancy.
  • Christchurch Medicine Information Service for patient-facing drug information.

• Anti-emetic and reflux-focused content (two scenarios in the PowerPoint)

  • Topics covered: nausea and vomiting in pregnancy, morning sickness, hyperemesis gravidarum, anti-reflux medications.
  • Core messages:
  • Assess the balance of benefits and risks of antiemetic therapy, guided by professional statements and available resources.
  • Revisit prior history and ensure documentation of prior episodes and responses to therapies.
  • Confirm whether the chosen therapy is within the midwife’s scope and supported by evidence and policy.
  • Two important consensus considerations:
  • When prescribing, ensure a full assessment and informed consent; revisit past history and whether any factors were missed previously.
  • If considering complementary or alternative therapies, rely on consensus statements and evidence and ensure appropriate training and scope before applying.

• Medication considerations and practical prescribing notes

  • First-line antiemetics often discussed in maternity practice include:
  • Metoclopramide (Maxalon): available in oral and IV forms; used for nausea and vomiting in pregnancy and in labour-related nausea. Consider IV route for rapid relief in dehydration scenarios; can transition to oral as tolerated.
  • Prochlorperazine (Stemetil): IV/IM forms; used for antiemetic effects but requires monitoring for extrapyramidal symptoms and safety in pregnancy.
  • Cyclizine (Cyclizine): commonly used in the community; available in oral and sometimes parenteral forms; consider in patients who can tolerate oral therapy.
  • Buccal or sublingual forms may be discussed in certain settings; ensure correct administration route and absorption considerations.
  • Cautions and practice considerations
  • In pregnancy, especially first trimester, carefully evaluate fetal safety and if data support the chosen agent; some agents carry teratogenic concerns and risk profiles vary by gestational age.
  • For early pregnancy, ensure movements and fetal development considerations are discussed with the patient and documented.
  • In the third trimester, certain antiemetics may have different safety profiles and effects on labor; consider prostaglandin-related effects and timing of birth.
  • If opioids are involved (e.g., for labor analgesia), antiemetic use is common but plan the combination carefully to minimize nausea; always add antiemetic to an opioid rather than mixing in reverse order to reduce nausea from opioids.
  • B6 (pyridoxine) and other supplements
  • Pyridoxine (B6) is commonly used, but emerging evidence suggests the need to monitor for possible overuse; stay updated on new literature and guidelines.
  • Evidence context and research notes
  • Ginger: Cochrane review shows inconsistent and not definitive evidence on safety and efficacy; use with caution and in line with consensus statements and training.
  • Acupuncture/acupressure: evidence is mixed; use only when aligned with complementary therapy consensus and with appropriate training.
  • Garlic and other CAM therapies: evidence is variable; rely on consensus statements and ensure patient safety and informed consent before recommending CAM therapies.

• Practical workflow in a case scenario (Sara) – case recap and assessment steps

  • Patient: Sara, 11 weeks gestation, BMI ~20; early pregnancy booking two weeks prior; morning sickness since 8 weeks with four days of worsening symptoms; unable to keep fluids or food down; past HG in a previous pregnancy.
  • Immediate assessment goals in clinic/community setting
  • Determine dehydration status and need for IV fluids.
  • Obtain baseline vitals and discuss tolerance of oral intake (fluids/food) and any electrolyte disturbances.
  • Review prior investigations and bloods; consider repeating full blood count if not recent.
  • Check for red flags requiring urgent transfer to hospital.
  • Confirm whether to initiate a discussion with obstetric team about management plan and potential admission.
  • Suggested investigations and actions in Sara’s case
  • Reassess hydration status; obtain vital signs; assess ability to tolerate fluids orally.
  • Consider ordered labs: FBC, LFTs, electrolytes (Na+, K+), uric acid, MSU, and urine ketones; arrange for bloods with clear plan for results.
  • Assess for ketones in urine as a marker of dehydration and starvation state.
  • If dehydration is suspected or cannot be managed in the community, initiate a plan for IV fluids and escalate to obstetric team via phone consultation.
  • A three-way discussion (patient, midwife, and obstetric team) via phone may be needed to decide on admission vs rapid outpatient management with IV fluids and antiemetics.
  • Communication and referral steps
  • Do not solely rely on community labs for urgent management if the patient’s condition is deteriorating or if dehydration is significant; coordinate with facility labs or urgent care.
  • If community capacity is constrained, arrange timely transfer to a center where IV fluids and monitoring are available.
  • Ensure documentation of the rationale for referral and the plan for ongoing management, including potential discharge with a plan and follow-up.
  • Treatment planning and escalation thresholds
  • If dehydration or intractable vomiting persists (unable to keep fluids down for >24–48 hours, or ketonuria, or weight loss), escalate to IV therapy and obstetric team involvement.
  • Involve dietitian for nutrition optimization when weight loss or poor intake is present.
  • Practical notes specific to this case
  • A three-way call (with Sara present) may be used to discuss management and consent for referral, with clear documentation.
  • Use of Espa or a similar handover tool to maintain concise, targeted communication.
  • Consider remote rural considerations and GP involvement in ongoing management when hospital access is limited.

• What to document and what to monitor (in this scenario and generally)

  • Documentation should include: current symptoms, hydration status, vitals, weight trend, intake tolerance, prior HG history, and the plan with/without referral.
  • Monitor: response to initial fluids and antiemetics, ability to tolerate oral intake, signs of improvement or deterioration, and need for escalation.

• Special considerations for prescribing in pregnancy (scope and safety)

  • The midwifery scope has evolved; extended scope considerations require training and evidence-based justification for any prescribing beyond standard practice.
  • When selecting medications, cross-check NZF, Medsafe labeling, gestational age, and breast-feeding considerations.
  • If considering non-conventional therapies (e.g., acupuncture, acupressure, garlic, ginger), ensure alignment with consensus statements and documented training.
  • Clear communication about the plan and consent is essential; when in doubt, refer to obstetric or medical teams early.

• NVP/HG and labour considerations

  • Nausea and vomiting in labour may occur; antiemetic use around labour is common, especially with opioids.
  • If combining opioids with antiemetics, the preferred practice is to administer the opioid first, then add the antiemetic to mitigate nausea from opioids.
  • Some antiemetics may be avoided or used with caution in labour due to effects on fetal/metal movement or labour timing; decisions should follow the labour and obstetric team guidance.

• Breaks, logistics, and follow-up

  • If the session requires a short break, ensure a handover of patient cases and any urgent plans before resuming.
  • For ongoing cases like Sara, ensure timely follow-up with obstetric team and maintain a clear plan for potential admission or outpatient management.

• Summary takeaways for exam and practice

  • Distinguish NVP from HG by severity, duration, and impact on hydration and nutrition; HG requires closer monitoring and potential admission.
  • Use a structured assessment to inform management: hydration status, weight, vitals, prior HG history, and current intake.
  • Early escalation to obstetric team is appropriate for severe dehydration, ketonuria, weight loss, or when management is beyond the midwife’s scope.
  • IV fluids are a mainstay for dehydrated HG in hospital settings; typical initial hydration is $2 ext{–}3 ext{ L}$ of IV fluids, with maintenance fluids (e.g., $1 ext{ L}$ NS daily) as tolerated, and IV glucose if needed.
  • Multidisciplinary care (midwife, obstetric team, dietitian) optimizes outcomes for HG with nutritional support and weight maintenance.
  • Ongoing review of medications, their safety in pregnancy, and alignment with NZ guidelines is essential; avoid unsubstantiated prescribing and ensure informed consent.

• Key figures and references to review later

  • NZ formulary guidance on antiemetics and subsidisation details.
  • Midwifery Council scope of practice (updated October 2020).
  • Soma’s position statements on nausea and vomiting in pregnancy and hyperemesis gravidarum pathways.
  • Christchurch Medical Information Service resources for drug information and clinical guidance.
  • Cochrane reviews on ginger and complementary therapies for NVP, highlighting the need for cautious interpretation of evidence and adherence to consensus statements.