Folder created in collaboration with Prof. Mickaël NAASSILA, Director of INSERM (National Institute of Health and Medical Research) ERI 24 Research Group on Alcohol & drug addictions (GRAP).
Alcohol and pregnancy: fetal alcohol syndrome
Prenatal exposure to alcohol has permanent and dramatic effects. Ethanol readily crosses the placenta and fetal concentrations are close to those of the mother. Disturbances can range from minor behavioral abnormalities to severe development disorders manifested by fetal alcohol syndrome (FAS): malformation of the skull and face, growth retardation, behavioral and cognitive disabilities. Nearly one in two children with FAS has mental retardation and most have problems with learning, memory, attention or behavior. The incidence of this syndrome is estimated at 0.5 to 3 cases per 1000 births in France, about 400 to 1200 cases per year.
The consumption of alcohol is harmful for the entire gestational period and it has never been demonstrated threshold below which risk is none where the recommendations from Zero alcohol during pregnancy.
Alcohol consumption during pregnancy can impact upon the child’s psychomotor development.
Fetal alcohol syndrome (FAS) was first described in 1968. The diagnosis is based on a combination of signs observed in children born to mothers who consume alcohol to excess. These signs may manifest as delayed pre- or post-natal growth, central nervous system abnormalities: neurological anomalies, delayed intellectual development, behavioral disorders, altered intellectual functions and/or structural anomalies [such as microcephaly (cranial perimeter < 3rd percentile) or brain malformations detected by imaging techniques or at autopsy], facial characteristics with minor craniofacial anomalies including narrow eyelids, an average-sized elongated face, an indistinct philtrum and a thin upper lip. There is also a higher frequency of other non-specific, congenital malformations, especially cardiac, skeletal and muscle tissue defects. The major problem concerning the future development of these children is the effect on the central nervous system. Almost one child in every two affected by FAS is mentally retarded (IQ < 70), and most present with learning, memory, attention or behavioral disorders.
FAS does not affect not all children born to women who consume excessive amounts of alcohol: genetic, nutritional or environmental factors could intervene in the aetiology of this syndrome. There is a continuum of anomalies and some children who have been exposed prenatally to alcohol may have central nervous system defects without any facial changes or FAS-induced retarded growth.
The incidence of this syndrome (number of cases per 1 000 births) is difficult to determine, mainly due to the diagnostic difficulty based at birth on craniofacial anomalies and retarded growth. Moreover, estimations differ according to the geographical region in question and therefore depend on female alcohol consumption levels. The incidence is estimated at 0.5-3.0 per 1 000 births with higher levels being recorded in some populations. A study conducted in Roubaix between 1986 and 1990 quotes an incidence of 2.3 per 1000.
There is no doubt as to the teratogenic potential of high levels of alcohol. The effects on children of exposure to lower doses than those triggering foetal alcoholisation syndrome are less well understood. Women of child-bearing age consume less alcohol than men. When they are pregnant, most women reduce their alcohol consumption, generally as from the first trimester of pregnancy. In the perinatal survey conducted in 1995 in all French maternity hospitals (representative sample), 5 % of the women interviewed at the hospital declared that they drank at least one glass of alcohol per day during their pregnancy; in 1998, this percentage was 3.9 %. Similarly, a study carried out at the Roubaix Maternity Hospital confirmed a lower declared consumption rate in pregnant women: 15 % of the women drank at least 2 glasses per day in 1985-1986, compared with 10 % in 1990-1991 and 4 % in 1992.
Excessive alcohol consumption affects female fertility. In men and women, moderate alcohol intake is not associated with reduced fertility. An increased perinatal mortality or prematurity has been observed in certain studies in cases where about two glasses/day were consumed but the confounding factors are not always checked. The birth weight is, on average, lower for children exposed in utero to average or high alcohol levels. The results are less marked for lower exposures (less than 2 glasses per day), some studies showing differences for the consumption of one glass/day and others not observing any effect under the consumption of 3 or 4 glasses/day. Therefore, no threshold under which there would be no impact on birth weight has been established.
Follow-up studies have been carried out to monitor children exposed to variable alcohol consumption during pregnancy: the children underwent a psychomotor development or IQ (intellectual quotient) test as babies or young children. Some of these studies have shown that children exposed to more moderate levels of alcohol during pregnancy than children affected by FAS have intellectual deficits or behavioural disorders similar, albeit less marked, to those presenting with FAS. A reduction in IQ of the order of 5 to 7 points in children of pre-school or school age has been detected in cases where maternal alcohol consumption was more than or equal to 2 to 3 glasses/day. One of the studies that monitored children up until 14 years of age, demonstrated the effects of such consumption during pregnancy on memory and arithmetic skills and on the children’s reading ability. A threshold effect on cognitive functions corresponding to the consumption of 2 to 3 glasses/day cannot, however, be deduced. For lower rates of consumption, only studies involving a very large number of subjects could establish the presence or absence of any effects. Excessive one-time consumption (at least 5 glasses at one time) during pregnancy has also been linked with intellectual deficits in children. Epidemiological studies thus confirm the harmful effects on birth weight and on cognitive functions in children of the consumption of 2 glasses/day, some studies having demonstrated a dose-effect relationship. It should be remembered that, from the results obtained in experimental studies, it is not possible to confirm a dosing threshold under which maternal alcohol consumption during pregnancy has no risk to the offspring.