πŸ”‘ Key Learning

  • Gestational diabetes affects ~1 in 40 pregnancies; if risk factors are present screen at booking, and again at 24–28 weeks for all women. 
    • Diagnosis: fasting BM > 5.6 or OGTT > 7.8. (5, 6, 7, 8)
    • Management depends on fasting glucose:
      • FBM <7 β†’ diet, metformin, insulin 
      • FBM >7 β†’ start insulin directly.
  • All diabetic pregnancies require tighter glucose targets and folic acid 5mg + aspirin 75mg.
  • Routine antenatal scans include dating scan (11–14 weeks) and anomaly scan (18–21 weeks).
  • Combined screening (nuchal + serum markers) between 10–13 weeks estimates risk of trisomies.
  • Anti-D prophylaxis is offered to rhesus-negative women at 28 weeks.

🍭 Gestational Diabetes

Risk Factors

  • Asian or African-Caribbean ethnicity
  • Obesity - BMI > 30
  • Previous macrosomic baby (>4.5 kg)
  • Previous GDM
  • 1st-degree relative with diabetes

πŸ§ͺ Investigations

Screening

  • If no risk factors: OGTT at 24–28 weeks
  • If risk factors: OGTT at booking and 24–28 weeks

Diagnostic Criteria

  • Fasting glucose > 5.6 mmol/L
  • OGTT (2hr) > 7.8 mmol/L
  • πŸ’‘Tip: GDM = 5, 6, 7, 8

πŸ’Š Management of GDM

If fasting BM < 7

  1. Trial of diet and exercise for 2 weeks
  2. If inadequate β†’ start metformin
  3. If inadequate on metformin β†’ add insulin

If fasting BM > 7

(or if 6.1–6.9 + macrosomia/hydramnios)

  • Start insulin immediately

πŸ’‰ Management of Pre-existing Diabetes in Pregnancy

  • Stop all oral hypoglycaemics
  • Continue metformin
  • Start insulin
  • Prescribe:
    • Folic acid 5mg OD until 12 weeks (NTD risk)
    • Aspirin 75mg OD from 12 weeks (pre-eclampsia risk)
  • Anomaly scan at 20 weeks with 4-chamber heart view

🎯 Blood Glucose Targets in Pregnancy

  • Fasting: ≀ 5.3 mmol/L
  • 1 hour post-meal: ≀ 7.8 mmol/L
  • 2 hour post-meal: ≀ 6.4 mmol/L

πŸ“… Routine Antenatal Care

πŸ–₯ Imaging

  • Dating scan: 11–14 weeks
  • Anomaly scan: 18–21 weeks

🧬 Combined Screening Test (10–13 weeks)

  • Nuchal translucency
  • Serum PAPP-A and Ξ²-hCG
  • Estimates risk of:
    • Trisomy 21 (Down)
    • Trisomy 18 (Edwards)
    • Trisomy 13 (Patau)

πŸ” Further Testing if High Risk (>1:150)

If combined test result is > 1:150 risk = β€˜higher chance’ - offer women the following:

  • Non-invasive prenatal testing (NIPT)
    • Screens placental DNA in maternal blood. Quantifies DNA from chromosome 21, 18, 13.
    • Results: 'Low chance' or 'High chance' - then offer diagnostic testing 
  • If NIPT = High chance β†’ offer diagnostic testing:
    • CVS (<13 weeks)
    • Amniocentesis (>15 weeks)
  • Additional miscarriage risk from invasive tests: <0.5%

πŸ—“ Booking Visit (Usually by 10 weeks)

  • Check BP + urine dip - recheck at each appointment
  • FBC, blood group, Rh status
  • Screen for:
    • GDM (if RFs)
    • Pre-eclampsia (start aspirin from 12 weeks if indicated)

🩸 28-Week Visit

  • Offer Anti-D to all Rh-negative women
  • Repeat Anti-D at 31–34 weeks if using 2-dose regimen

πŸ’Š Antenatal Supplements

  • Folic acid:
    • 400 micrograms daily for all women
    • 5mg if high risk (e.g. diabetes, AEDs, obesity, Hx of NTD)
  • Vitamin D: 10 micrograms (400 IU) OD
  • Avoid Vitamin A supplements (risk of teratogenicity)

πŸ“ Exam Clues & Clinchers

  • Previous baby >4.5kg + BMI >30 β†’ GDM screen at booking and again at 24–28 weeks
    • Diagnosis: 5, 6, 7, 8
  • Fasting BM 5.9 β†’ GDM (trial diet, metformin, then insulin)
  • Fasting BM > 7? β†’ Insulin!

πŸ”— Useful Links & References