In November of 1996, the British Royal College of Obstetricians and Gynaecologists (RCOG) published an RCOG Guideline consisting of a brief overview with conclusions and recommendations concerning alcohol consumption during pregnancy (see Appendix). On the basis of present knowledge, we believe that some of the conclusions and recommendations may not be sound or may even convey some risk. The first conclusion of the RCOG Guideline states, ‘No adverse effects on pregnancy outcome have been proven with a consumption of less than 120 g of alcohol (around 15 units) per week’. A similar statement is made in the recommendations section. Although it is true that current evidence is not consistent in showing a clear relationship between lower levels of maternal alcohol consumption and adverse effects in the offspring, there are reasonable data that suggest that even low levels of ethanol consumption may be harmful to the fetus. For example, Day et al. (1994) reported a dose– response relationship between several parameters of growth (assessed to 6 years of age) and average daily volume of alcohol consumed during pregnancy. Adverse effects were clearly seen at one drink/day (13 g of ethanol/day), a level that the RCOG Guideline seems to tolerate. The above group (Goldschmidt et al., 1996) also reported a linear dose–response function between alcohol consumption and deficits on an arithmetic achievement test (the WRAT-R). Threshold effects of about one drink/day were found for the reading and spelling achievement subtests.
The RCOG Guideline ends with a recommendation that no more than one drink be consumed/day, but the majority of the paper emphasizes consumption levels on a weekly basis (e.g. 120 g or 15 U/week). We are very concerned that these weekly levels will become the benchmark against which risk is judged. An important factor to consider is whether the weekly intake is consumed on only one or two occasions (binge drinking) or divided over the entire week. There are substantial data indicating that blood-alcohol level, rather than the dose consumed, is critical in determining effects from prenatal alcohol exposure (e.g. Bonthius and West, 1990). Drinking 5 U, or 40 g of alcohol/ occasion once or twice a week, probably has a greater impact on development than the same amount consumed over a longer time (Jacobson et al., 1993; Jacobson and Jacobson, 1994; Streissguth et al., 1994). Indeed, Jacobson and Jacobson (1994) estimated that, when concentrated on one or two occasions/week, the lower threshold of maternal drinking for producing intellectual deficits is 91 g/week. A relationship between the Bayley Mental Developmental Index and pregnancy drinking level was found even in light drinkers (3.5–6.9 drinks/week or 45–89.7 g of ethanol/week) (Jacobson and Jacobson, 1994). Results from the Seattle longitudinal study also reported dose-dependent neurobehavioural effects, generally without a threshold, from the first day of life to 14 years of age (Streissguth et al., 1994, 1996). Furthermore, it may be that alcohol exposure of less than 120 g/week may cause cognitive and behavioural abnormalities, but that these only become apparent when the child is challenged during the school years (Streissguth et al., 1994, 1996).
There are also numerous animal studies showing that low blood-alcohol levels can induce both brain damage and behavioural alterations, including permanent decreases in the number of Purkinje and granule cells in the cerebellum (Napper and West, 1995), alterations in long-term potentiation (Savage et al., 1991) and impairments in learning and memory (Vaglenova and Petkov, 1998). Blood-alcohol levels equivalent to those noted in these animal studies (30–40 mg/dl), can be attained in a 60-kg individual after the consumption of 18 g of ethanol (Fraser et al., 1995).
Finally, it must be cautioned that threshold values are based upon group averages, therefore it is not appropriate to infer that exposure below a threshold level is necessarily ‘safe’, because of the marked inter- and intra-individual variations in alcohol pharmacokinetics (Eckardt et al., 1998). Some women or fetuses may be particularly susceptible or sensitive to these prenatal alcohol exposures. For example, the risk for intellectual impairment increased substantially in the offspring of women over the age of 30 years who drank during pregnancy (Jacobson et al., 1996).
Admittedly, we have much to learn about the consequences of lower levels of alcohol exposure during pregnancy and how these exposures might interact with various medical and environmental conditions. However, contrary to the conclusions in the RCOG, we believe that there are reasonable data indicating functional and physical consequences following exposure levels of less than 120 g of ethanol/week. Although we may never know the amount of alcohol any particular woman needs to consume to affect her child, we do know that these effects are 100% preventable. While one might advise the pregnant woman who has been drinking less than 2 U/day that the risk to the fetus is relatively small, given the current data, it would be clinically prudent to advise abstention during pregnancy.
ROYAL COLLEGE OF OBSTETRICIANS AND GYNAECOLOGISTS (RCOG) GUIDELINE NO. 9 (NOVEMBER 1996) ALCOHOL CONSUMPTION IN PREGNANCY
Despite repeated historical references to the deleterious effects of maternal alcohol consumption in pregnancy, it was not until 1968 that Lemoine and co-workers1 described a constellation of fetal growth and developmental defects associated with maternal and paternal alcohol abuse. Since then a range of fetotoxicity has been associated with heavy and social maternal alcohol consumption.
HEAVY ALCOHOL CONSUMPTION
Jones and colleagues2 were the first to coin the phrase “fetal alcohol syndrome” to describe the features associated with heavy maternal alcohol consumption. The diagnosis of fetal alcohol syndrome requires signs in all of the three following categories:
Fetal growth retardation.
Central nervous system involvement (neurological abnormalities, developmental delay, intellectual impairment, head circumference below the 3rd centile, brain malformation).
Characteristic facial deformity (short palpebral fissures, elongated mid-face, flattened maxilla).
Other abnormalities, affecting all systems in the body, have been described and are referred to as fetal alcohol effects. Fetal alcohol syndrome is a rare event with reported incidences of 1.7 per 1,000 and 3.3 per 1,000 live births in Sweden and France, respectively. The syndrome is not seen consistently in infants born to women who are heavy consumers of alcohol and occurs only in approximately 30–33% of children born to women who drink about 2 gms per kilogram of body weight per day (equivalent to approximately 18 units of alcoholic drink per day). The differing susceptibility of fetuses to the syndrome is thought to be multifactorial and reflects the interplay of genetic factors,3 social deprivation, nutritional deficiencies, tobacco and other drug abuse, along with alcohol consumption.
SOCIAL ALCOHOL CONSUMPTION
Moderate and occasional alcohol consumption which is socially acceptable is regarded as normal behaviour. Over 90% of the population consumes alcohol. The consequences of this social activity on pregnancy have remained controversial because it is a difficult area to study for two main reasons:
difficulty in measurement of alcohol consumption during pregnancy;
difficulty in controlling for confounding factors, particularly social class and tobacco consumption.
There are inconsistent data about the effect of social alcohol consumption on many pregnancy outcomes such as spontaneous miscarriage or preterm delivery rates. However, there is good evidence that social alcohol consumption does have a small negative effect on intrauterine fetal growth. Mills et al.4 reported an 83 gm decrement of birth weight per one to two drinks per day very similar to that found by Florey et al. in the Euromac study5, ie a deficit of 66 gms of birth weight per 120 gms of alcohol (15 units) per week.
Any impairment of neurodevelopment appears to occur at higher levels of alcohol consumption. The best information in this area comes from the Seattle Pregnancy and Health Study summarised in a recent review.6 The Seattle group reported a decrement of five IQ points in children of mothers drinking greater than 250 gms of alcohol per week, whilst at seven years of age, children of mothers drinking greater that 165 gms per week had a decrement of seven IQ points. Other impairments included attention and memory deficits, arithmetic and reading difficulties.
SCREENING FOR HEAVY ALCOHOL CONSUMPTION DURING PREGNANCY
Although 90% of women consume alcohol when they are not pregnant, the proportion decreases to 40%-60% during pregnancy. Most women are able to abstain or decrease their alcohol consumption during pregnancy because for them it is not an addictive activity. However, obstetricians should be aware of the possibility of heavy alcoholic consumption during pregnancy because of the potentially serious effects on the fetus. One method of assessment is to include within a dietary and substance-use history a retrospective week's diary of alcohol consumption, including lunchtime and early evening drinking. More promising is the T-ACE questionnaire devised by Sokol et al.7 which can be used to screen either the whole population or be targeted at those women with growth impaired fetuses. Only four questions are required as follows:
T How many drinks does it take to make you feel high? (Tolerance) (The patient is considered tolerant if it takes more than two drinks to make her feel high) - two points
A Have people annoyed you by criticising your drinking? - one point
C Have you ever felt you ought to cut down your drinking? - one point
E Have you ever had a drink first thing in the morning to steady your nerves or to get rid of a hangover (eye opener)? - one point
A total score of greater than or equal to two points is considered positive and correctly identifies approximately 70% of heavy drinkers during pregnancy.
Biological markers of excessive alcohol consumption include blood gammaglutamyl transferase, alcohol concentration and thiocyanate, mean corpuscular volume. None of these is precise and better markers are being developed.
No adverse effects on pregnancy outcome have been proven with a consumption of less than 120 gms of alcohol (around 15 units) per week.
Consumption of 120 gms (15 units) or more per week has been associated with a reduction in birth weight.
Consumption of more than 160 gms (20 units) per week is associated with intellectual impairment in children.
In pregnancy heavy alcohol consumers will require specific counselling and possible referral for special treatment. This is especially true for binge drinkers where the effects on the fetus remain uncertain, but will nonetheless cause concern to both the mother and the obstetrician. Clinics should consider providing a telephone contact number for woman seeking advice and support for alcohol problems.
There is no conclusive evidence of adverse effects in either growth or IQ at levels of consumption below 120 gms (15 units) per week. Nonetheless, it is recommended that women should be careful about alcohol consumption in pregnancy and limit this to no more than one standard drink per day.
1 unit of alcohol approximately equals 8 gms of absolute alcohol which is equivalent to:
½ pint of ordinary strength beer, lager, cider
¼ pint of strong beer or lager
1 small glass of wine
1 single measure of spirits
1 small glass of sherry
This guideline was produced under the direction of the Scientific Advisory Committee of the Royal College of Obstetricians and Gynaecologists as an educational aid to obstetricians and gynaecologists. This guideline does not define a standard of care, nor is it intended to dictate an exclusive course of management. It presents recognised methods and techniques of clinical practice for consideration by obstetricians/gynaecologists for incorporation into their practices. Variations of practice taking into account the needs of the individual patient, resources and limitations unique to the Institution or type of practice may be appropriate.