Mothers who drink even low levels of alcohol during pregnancy could permanently damage their children's intelligence, research suggests.
The study of seven-and-a-half-year-olds by scientists in Detroit found lower IQ scores, and memory and problem-solving difficulties among those who had had low-level exposure to alcohol during pregnancy.
The research, which the Department of Health says it wants to consider, appears to challenge current British Government advice that pregnant women can safely consume one to two units of alcohol a week.
It has long been established that serious problems such as severe learning difficulties and physical abnormalities can occur when women drink large amounts of alcohol during pregnancy, leading to foetal alcohol syndrome (FAS).
Researcher Matthew Burden, from Wayne State University, said: "Prenatal alcohol exposure is often associated with slower reaction times and poorer attention in infancy and some of these deficits may be at the core of poorer academic performance and behaviour problems often seen later in childhood.
This is because alcohol consumed by the mother has a direct impact on the brain of the foetus.
"However, full FAS is not required to see this impact � it is just less obvious to detect across the array of exposures found in foetal alcohol spectrum disorders (FASD), which include effects of prenatal alcohol at lower drinking levels."
Ms Croxford said: "This is likely to mean that these children may be more and more challenged the older they get by the demands placed on them within the school system and within their day-to-day social interactions.
Campaigners in the UK have said that the only definitely safe level of alcohol during pregnancy is no alcohol at all, saying that recommended limits are too high.