Fetal alcohol syndrome

What is fetal alcohol syndrome (FAS)?¹

Alcohol is a known teratogen, but the science underlying its effects still continues to be developed. Multiple studies using animal models have shown that even low levels of alcohol exposure can lead to developmental abnormalities, at all stages of embryonic development. Alcohol can have characteristic impacts on development that persist after birth and throughout life.

It may also include structural deficits and/or birth defects involving ears, eyes, palmar creases, digits, elbow, joints and heart. Children with FASD are also at increased risk of additional structural defects including congenital heart defects and orofacial clefts.

Some individuals affected by pre-natal alcohol exposure may also have recognisable facial characteristics. This pattern of anomalies is referred to as fetal alcohol spectrum disorder (FASD) with sentinel facial features (see 'Clinical features' below).

However, in more than 90% of cases the sentinel facial features are not present. The diagnosis is then referred to as FASD without sentinel facial features.

Therefore the diagnostic terms are now:²

• Fetal alcohol spectrum disorder with sentinel facial features (formerly fetal alcohol syndrome).

• Fetal alcohol spectrum disorder without sentinel facial features (formerly partial fetal alcohol syndrome, alcohol-related neurological disorder, alcohol-related birth defects, or neurobehavioural disorder-prenatal alcohol exposure.

How common is fetal alcohol syndrome? (Epidemiology)³

Prenatal alcohol exposure is the leading preventable cause of cognitive deficit in developed countries.⁴

Exact numbers are difficult to define in this spectrum of disorder and there are no accurate figures for prevalence in the UK.

This is due to a number of factors, including the differing definitions and conditions along the spectrum, the poor accuracy in self-reporting of alcohol consumption, lack of standardisation of levels of drinking, reluctance to make or accept the diagnosis, and paucity of reliable data collection.

Fetal alcohol spectrum disorder is underdiagnosed. Global prevalence of fetal alcohol spectrum disorder is estimated at 0.77%, with a higher prevalence of 2-5% in Europe and North America.⁵

Fetal alcohol syndrome risk factors¹

The sole risk factor is maternal consumption of alcohol during pregnancy. Individuals can experience a wide range of problems, of varying degrees of severity. The severity depends on the timing, frequency and level of alcohol exposure.

Higher levels of alcohol consumption increase the risk. There appear to be critical periods during the pregnancy where a given dose of alcohol will have a much more serious effect than if given at another time, but the exact timing when these critical periods are remains unclear.

Not all women who drink heavily during pregnancy have babies with FAS and it is clear that other factors affect the vulnerability of the fetus. These include the stage of pregnancy affected, the pattern of drinking, the health, age, stress levels and nutritional status of the mother and the use of other toxic substances, including tobacco.³

Genetic makeup and gene polymorphisms also strongly affect fetal vulnerability for FAS, and other genetic abnormalities can be confused with FAS.⁶ Features of FAS may be passed on to subsequent generations, due to structural chromosomal changes caused by prenatal alcohol exposure.⁷

Clinical features^{1 8}

Alcohol can have characteristic impacts on development that persist after birth and throughout life. These may include pervasive and long-standing central nervous system dysfunction in the following areas: motor skills, neuroanatomy or neurophysiology, cognition, language, academic achievement, memory, attention, executive function (including impulse control and hyperactivity), affect regulation, and adaptive behaviours, social skills or social communication.

It may also include structural deficits and/or birth defects involving ears, eyes, palmar creases, digits, elbow, joints and heart. Children with FASD are also at increased risk of additional structural defects including congenital heart defects and orofacial clefts.

Some individuals affected by pre-natal alcohol exposure exhibit most of the issues listed above, alongside a set of recognisable facial characteristics. This pattern of anomalies is referred to as fetal alcohol spectrum disorder (FASD) with sentinel facial features (see 'Clinical features' below). The 3 definitive facial features can include the following:

• Short palpebral fissure (small eyes).

• Thin upper lip.

• Smooth philtrum (area between the mouth and nose).

In more than 90% of cases the sentinel facial features are not present. The diagnosis is then referred to as FASD without sentinel facial features.

Features such as a flat midface are characteristic but not easily measured as part of the core features, and therefore not included in routine non-specialist assessments. Associated features develop in early pregnancy and may not be seen in many cases; these include skin folds inner eye corner, low set pointed ears, short nose and small jaw.

FASD is linked to a range of other conditions known as co-morbidities, which include:

• Microcephaly, seizure disorder, spinal cord abnormalities, structural brain abnormalities (including corpus callosum, cerebellum, caudate, and hippocampus).

• Enteric neuropathy.

• Chronic serous otitis media, conductive and/or neurosensory hearing loss.

• Aberrant great vessels, atrial septal defects, ventricular septal defects.

• Aplastic, dysplastic or hypoplastic kidneys, horseshoe kidney, hydronephrosis, ureteral duplications.

• Camptodactyly, clinodactyly, flexion contractures, hypoplastic nails, radioulnar synostosis, scoliosis, spinal malformations.

• Cleft lip, cleft palate.

• Attention-deficit/hyperactivity disorder, conduct disorder, intellectual disability, language disorders, learning disabilities, mood disorders, oppositional defiant disorder, sensory processing issues, substance use disorders.

• Ptosis, retinal malformation, strabismus, visual impairment.

Management

Management is multidisciplinary and includes managing comorbid conditions, providing nutritional support, managing behavioural problems and educational difficulties, referring for rehabilitative therapies, and providing support and education for parents.⁹

Prognosis¹

The neuro-developmental problems associated with FASD can create great difficulties in childhood that persist throughout life. Impaired ability to learn, remember, make judgements and forward plan make day-to-day life very challenging. This results in problems at school, trouble with the law, substance misuse problems and risky or inappropriate sexual behaviours.

Although some effects of FASD can improve over time, it is common for secondary disabilities to develop as a result of other problems. The cognitive deficits, behavioural problems, psychopathology and other secondary disabilities associated with FASD affect an individual’s ability to navigate their daily life and become independent adults.

One study in the US found that the life span prevalence was 61% for disrupted school experiences, 60% for trouble with the law, 50% for confinement (in detention, jail, prison, or a psychiatric or alcohol or drug inpatient setting), 49% for inappropriate sexual behaviours on repeated occasions, and 35% for alcohol or drug problems. This study found a 2 to 4 fold reduction in the odds of developing these adverse outcomes if a diagnosis was made before the age of 12.

In Germany, a small 20 year study focussed on some of the most complex cases of FASD. They followed 37 patients who showed very poor outcomes following a psychosocial and career interview. 18 subjects (49%) had received special education only, 14 (38%) had passed primary school, and only 5 (13%) had a secondary school education. By occupational status, only 5 subjects (13%) had ever held an ‘ordinary’ job. This is despite 69% having received some preparatory job training (but with 19% terminating this prematurely). Although the study participants were among those most severely affected, the study highlights the extent of life-long social challenges that FASD can cause.

Fetal alcohol syndrome prevention³

Both fetal alcohol syndrome and FAEs are entirely preventable. Estimates of alcohol consumption in the general population and pregnant women are difficult as there is known to be significant under-estimation and under-reporting.

One study from Leeds of pregnant women aged 18-45 showed that more than 79% drank alcohol in the first trimester of pregnancy, 63% in the second and 49% in the third, with significant numbers drinking over two units per day.¹¹

Many pregnancies are unplanned, so much of the alcohol consumed during pregnancy may be at a time when the woman was unaware she was pregnant. Women should then be advised to avoid further drinking, and reassured that it is unlikely in most cases that the baby has been affected.¹