The risk of harm increases with alcohol intake, but there is no proven safe level of alcohol in pregnancy. Complete abstinence is the safest approach.
About
- Fetal Alcohol Syndrome (FAS) is the most severe form of the fetal alcohol spectrum disorders (FASD).
- Alcohol freely crosses the placenta and is teratogenic to the developing central nervous system (CNS).
- It is defined by the triad of:
- Pre- and postnatal growth restriction
- Characteristic facial features
- Neurodevelopmental impairment
- First described by Jones & Smith in 1973.
Aetiology
FAS is caused by maternal alcohol consumption during pregnancy. The fetus lacks the enzymes to metabolise alcohol effectively, leading to prolonged exposure.
- Timing: First trimester exposure most harmful for structural malformations; later exposure disrupts growth and neurodevelopment.
- Pattern: Binge drinking may be particularly damaging due to high peak ethanol levels.
- Maternal health factors: Malnutrition, smoking, or co-drug use exacerbate risk.
- Genetic susceptibility: May influence fetal vulnerability.
Clinical Presentation
- Growth Restriction: Low birth weight, poor postnatal growth, short stature.
- Facial Features (classic dysmorphia):
- Short palpebral fissures
- Smooth/flattened philtrum
- Thin vermilion border of upper lip
- Neurological / Cognitive: Microcephaly, learning difficulties, poor executive function, hyperactivity, attention deficits.
- Congenital anomalies: Cardiac defects (e.g. VSD, ASD), renal anomalies, joint abnormalities.
- Behavioural / Emotional: Poor social judgment, impulsivity, high rates of ADHD, anxiety, and depression.
Investigations
FAS is primarily a clinical diagnosis, but investigations can support exclusion of other conditions and characterisation of damage.
- History: Confirm maternal alcohol exposure if possible (often under-reported).
- Physical exam: Facial features, growth parameters, congenital anomalies.
- Neuropsychological testing: Learning profile, behavioural assessment.
- Imaging: MRI may show corpus callosum agenesis, cerebellar hypoplasia, or other structural CNS abnormalities.
- Genetic testing: To exclude chromosomal syndromes (e.g., Down, Williams).
Differential Diagnoses
- Genetic syndromes: Down syndrome, Williams syndrome.
- Intrauterine growth restriction (IUGR): due to placental or maternal causes.
- Other teratogen exposures: Anticonvulsants (valproate), retinoic acid, etc.
- Neurodevelopmental disorders: Autism spectrum disorder, ADHD.
Management
There is no cure for FAS. Management is multidisciplinary, aiming to optimise function and prevent secondary harm.
- Prevention: Public health campaigns, education, and absolute abstinence from alcohol in pregnancy.
- Medical care: Treat congenital anomalies (e.g., cardiac surgery), manage growth and feeding problems.
- Neurodevelopmental support: Early intervention with speech therapy, occupational therapy, physiotherapy.
- Educational interventions: Special education plans, structured teaching environments.
- Psychological / Behavioural therapy: CBT, social skills training, support for ADHD/anxiety.
- Family support: Parenting programs, safeguarding, support groups.
Prognosis
- Neurodevelopmental and behavioural difficulties are usually lifelong.
- Congenital anomalies may require surgical or medical interventions.
- With early recognition, multidisciplinary input can improve school performance and social outcomes.
- Supportive families and structured environments are protective.
References
- Jones KL, Smith DW. Recognition of the fetal alcohol syndrome in early infancy. Lancet. 1973.
- Mattson SN, Riley EP. Fetal Alcohol Spectrum Disorders: Neuropsychological and Behavioral Features. Exp Biol Med. 1998.
- Popova S, et al. Fetal Alcohol Spectrum Disorders—An Update. N Engl J Med. 2016;374:1791-1798.
- Hoyme HE, et al. Updated clinical guidelines for FASD diagnosis. Pediatrics. 2016.
- NICE Guideline NG3. Antenatal care for uncomplicated pregnancies. 2021.