Obesity in pregnancy — structured oral station (12 minutes)

Opening prompt — "Build me her antenatal plan."

Model response — say it in this order: ^[1][2]

• "BMI 44 is class III obesity — this convenes the multidisciplinary team. I would plan anaesthetic, midwifery, obstetric and dietetic input together, confirm bariatric theatre equipment, and book a specialist anaesthetic clinic in the third trimester."
• "At booking I would measure (not ask) weight and height, use a correctly sized BP cuff, start vitamin D 1000 IU daily, aspirin 150 mg nocte from 12 weeks given her added risk, a VTE risk score in the chart, an early glucose workup and a 75 g OGTT at 24 to 28 weeks, a STOP-BANG OSA screen, and a customised growth chart with serial ultrasound from 28 weeks."
• "Thirty screens, thirty-five refers, forty convenes — she is at the convene tier."^[1][2]

Examiner is listening for: the three-threshold rule, the named doses, and the MDT framing — not 'lifestyle advice'. ^[1]

Probe 1 — "Why the higher-dose aspirin, and not the legacy lower dose?"

• "Aspirin 150 mg nocte from 12 to 36 weeks is the preeclampsia-prevention dose for BMI above 35 with one other risk factor. Obesity drives endothelial dysfunction and impaired spiral artery remodelling; the 150 mg dose partially restores the prostacyclin-thromboxane balance. The legacy 75 mg is below the prevention threshold."^[1]
• "Her added risk here is the previous caesarean, OSA and advancing age — she meets several criteria."^[1]

Probe 2 — "She will need a caesarean. How do you dose her enoxaparin?"

• "Weight-based enoxaparin 0.5 mg/kg subcutaneously twice daily — not fixed-dose 40 mg. Fixed-dose and BMI-stratified regimens under-dose around three-quarters of obese women."^[5][6]
• "Overcash 2015: 86 percent of morbidly obese post-caesarean women on 0.5 mg/kg twice daily achieved prophylactic anti-Xa, versus 26 percent on BMI-stratified dosing. Stephenson 2016, the RCT: 88 percent versus 14 percent on fixed-dose 40 mg daily. No level reached the therapeutic threshold. I would continue for at least 10 days, extended to 6 weeks at BMI 40 and above."^[5][6]

Probe 3 — "Her OSA is on home CPAP. What does that change?"

• "Plan CPAP in labour and nocturnal SpO2 monitoring post-caesarean; favour regional anaesthesia and avoid opioids where possible because of sedation risk; recover her in a monitored bed; involve the anaesthetist early. OSA compounds the already eight-fold higher failed-intubation risk in obesity."^[1][2]

Probe 4 — "She is anxious about the birth and asks what could go wrong."

This is a scored domain, not a courtesy. Demonstrate it out loud: ^[1]

• Move to her eye level, use her name, acknowledge the fear plainly: "Your BMI does change some risks — a harder anaesthetic, a higher chance of wound problems and clots — and that is exactly why we plan all of this now, with the anaesthetist and the team, weeks before your due date."
• Be honest and specific without catastrophising: name the plan for the airway, the wound, the clot prevention. Avoid jargon and avoid conducting the conversation with your back turned. ^[1]

Probe 5 — "She asks about a VBAC. How do you counsel her?"

• "VBAC success is lower in obesity — around 50 to 60 percent versus 70 to 75 in normal weight — and scar dehiscence and rupture risks are higher. Emergency caesarean in labour carries more risk than a planned repeat caesarean in class III obesity. I would counsel honestly, document the discussion, and lean toward planned caesarean unless she has strong preferences and favourable factors."^[1]