Smoking in pregnancy

M R C O G PA R T 2 · S O S P O C K E T C A R D · K N O W L E D G E A R E A 5 – A N T E N ATA L C A R E

Smoking in Pregnancy: Pathophysiology of Harm, Monitoring & Cessation McDonnell BP, Regan C. Smoking in pregnancy: pathophysiology of harm and current evidence for monitoring and cessation. TOG 2019;21:169–175. doi:10.1111/tog.12585

10.4% 27–47% <1/3 ENGLAND SMOKING AT DELIVERY, 2018 Q1 QUIT WITHIN 1ST TRIMESTER SPONTANEOUS QUITTERS ABSTINENT AT 1YR (TARGET ≤6% BY 2022) POSTPARTUM

DO N' T-M IS S FA C TS

  1. Smoker baseline carboxyhaemoglobin 4% (3–8%) vs non-smoker 1%; heavy smoker up to 15% – CO left-shifts O₂–Hb curve

  2. NICE: universal exhaled CO screening at booking; opt-out referral for all current/occasional smokers and quitters <2 weeks; >4 ppm denying non-smoker → second-hand smoke advice

  3. Nicotine = neuro-teratogen (fetal nicotinic acetylcholine receptors); tar carries carcinogens; cadmium accumulates in placenta

  4. 27–47% quit in 1st trimester, but <1/3 of spontaneous quitters abstinent at 1yr postpartum

  5. Five As: Ask, Advise, Assess, Assist, Arrange

  6. 2018 Cochrane: NRT+behavioural support ↑cessation at end of pregnancy, no effect on postpartum cessation; NICE/RCOG – NRT as adjunct only

  7. No RCT/observational safety or efficacy data for e-cigarettes in pregnancy; NIHR trial results due 2021

  8. England smoking-at-delivery: 10.4% (2018 Q1), target ≤6% by 2022

CESSATION AID EVIDENCE TIERS

Psychosocial (counselling/feedback/incentives): effective, also ↓low birthweight & ↓NICU admission

NRT: weak evidence, adjunct only, no postpartum effect E-cigarettes: no pregnancy safety/efficacy data

ABBREVIATION KEY

NICE — National Institute for Health and Care Excellence SIDS — sudden infant death syndrome

NRT — nicotine replacement therapy RCOG — Royal College of Obstetricians and Gynaecologists

CO — carbon monoxide NCSCT — National Centre for Smoking Cessation and Training

COHb — carboxyhaemoglobin NIHR — National Institute for Health Research

ppm — parts per million RCT — randomised controlled trial

ADHD — attention deficit hyperactivity disorder

Source: The Obstetrician & Gynaecologist (TOG), RCOG journal — TOG 2019;21:169–175. doi:10.1111/tog.12585

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